Reactions of cyclopentadienvl-amidinate titanium imido compounds with CS2, COS, isocyanates, and other unsaturated organic compounds

Article abstract of DOI:10.1021/om050784v

New single-, double-, and cross-coupling and imido group transfer reactions of cyclopentadienyl-amidinate titanium imido complexes are described. Reaction of Ti(η-C₅R₄Me)(N^tBu)Cl(py) (R = Me or H) with the lithiated benzam

Full text of DOI:10.1021/om050784v

Organometallics 2006, 25, 1167-1187
1167
Reactions of Cyclopentadienyl-Amidinate Titanium Imido
Compounds with CS2, COS, Isocyanates, and Other Unsaturated
Organic Compounds
Aldo E. Guiducci, Catherine L. Boyd, and Philip Mountford*
Chemistry Research Laboratory, UniVersity of Oxford, Mansfield Road, Oxford OX1 3TA, U.K.
ReceiVed September 10, 2005
New single-, double-, and cross-coupling and imido group transfer reactions of cyclopentadienyl-
amidinate titanium imido complexes are described. Reaction of Ti(η-C5R4Me)(NtBu)Cl(py) (R ) Me or
H) with the lithiated benzamidinate Li[PhC(NSiMe3)2] or acetamidinate Li[MeC(NiPr)2] afforded the
tert-butyl imido complexes Ti(η-C5R4Me)(NtBu){PhC(NSiMe3)2} (R ) Me (5) or H (7)) and Ti(η-C5R4-
Me)(NtBu){MeC(NiPr2)2} (R ) Me (6) or H (8)), respectively. Reaction of 6 with ArNH2 or TolNH2 (Ar
) 2,6-C6H3Me2, Tol ) 4-C6H4Me) afforded the corresponding aryl imido complexes Ti(η-C5-
Me5)(NR){MeC(NiPr2)2} (R ) Ar (9) or Tol (10)). Complexes 5, 7, and 8 underwent cycloaddition/
extrusion reactions with CS2 and COS to form µ-sulfido dimers and tBuNCS and tBuNCO, respectively.
t
Compound 6 reacted with COS to form BuNCO and [Ti(η-C5Me5)(µ-S){MeC(NiPr)2}]2, but with CS2
additional insertion into an amidinate ligand Ti-NiPr bond occurred to form [Ti(η-C5Me5)(µ-S){N-
(iPr)C(Me)N(iPr)C(S)S}]2. For the aryl imido compounds 9 and 10 the intermediate cycloaddition products
Ti(η-C5Me5){N(R)C(E)S}{MeC(NiPr)2} (E ) S or O) were observed. No further insertion of CS2 or
t
COS into the Ti-NR bonds occurred. All tert-butyl imido compounds reacted slowly with BuNCO or
t
t
ArNCO to form µ-oxo-bridged dimers and BuNCNtBu or BuNCNAr, respectively. Reaction of 9 with
tBuNCO gave the N,O-bound ureate Ti(η-C5Me5){N(Ar)C(NtBu)O}{MeC(NiPr)2}, which extruded
tBuNCNAr to form [Ti(η-C5Me5)(µ-O){MeC(NiPr)2}]2. Reaction of 9 or 10 with aryl isocyanates gave
the N,O-bound ureates Ti(η-C5Me5){N(R1)C(NR2)O}{MeC(NiPr)2} (R1 ) Ar, R2 ) Ar or Tol; R1 )
Tol, R2 ) Ar or Tol (25)), which did not undergo extrusion. Reaction of 25 with TolNCO gave the net
cycloaddition-insertion product Ti(η-C5Me5){OC(NTol)NTolC(NTol)O}{MeC(NiPr)2}. Several hetero-
cumulene cross-coupling cycloaddition-insertion reactions were studied: for example, the sequential
reaction of 10 with TolNCO and CO2 gave Ti(η-C5Me5){OC(O)NTolC(NTol)O}{MeC(NiPr)2}. Aryl
imides 9 and 10 reacted with TolNCNTol to form the guanidinate complexes Ti(η-C5Me5){N(Tol)C-
t
(NTol)N(R)}{MeC(NiPr)2} (R ) Ar or Tol). Reaction of 5 and 6 with PhNO gave BuNdNPh and
µ-oxo-bridged dimers; the aryl imides 9 and 10 reacted similarly. Ketone and aldehyde CdO/TidNR
bond metathesis reactions occurred for certain tert-butyl and aryl imido compounds with MeCOMe,
PhCOPh, PhCOH, and PhCOMe, and in some instances intermediates were observed. Slow imide/imine
metathesis occurred between Ti(η-C5Me5)(N-4-C6H4NMe2){PhC(NiPr2)2} and PhCH(NTol). Compound
6 rapidly converted PhCONH2 and Me(CH2)4CONH2 to the corresponding nitriles, but the analogous
t
reaction with BuCONH2 was slower. Several other titanium imido compounds and Ti(NMe2)2Cl2 were
also evaluated for the PhCONH2 dehydration reaction.
chemistry, the imido ligand (NR, where R is typically an organic
group) can act as either a spectator ligand (as found in imido-
supported olefin metathesis7,10,16 or Ziegler-Natta polymeri-
zation19 catalysts) or as a reactive site (typically via coupling
of the MdNR bond with unsaturated substrates, but also via
C-H bond activation). Some of the most reactive metal-imido
Introduction
Terminal transition metal imido compounds have been of
continuing interest for over two decades, and a good deal of
this chemistry has been reviewed.1-20 In terms of reaction
* To whom correspondence should be addressed. E-mail:
philip.mountford@chem.ox.ac.uk.
(1) Nugent, W. A.; Haymore, B. L. Coord. Chem. ReV. 1980, 31, 123.
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10.1021/om050784v CCC: $33.50 © 2006 American Chemical Society
Publication on Web 01/24/2006

1168 Organometallics, Vol. 25, No. 5, 2006
Guiducci et al.
Chart 1
Scheme 1. Synthesis of Cyclopentadienyl-Amidinate Imido
Compounds
linkages have been found for the group 4 elements.3,4,11,12,15,20,21
In this contribution we focus on titanium imido chemistry in
particular.22
together with a detailed study of their reactions with other
organic substrates, namely, CS2, COS, isocyanates, carbodi-
imides, PhNO, ketones, PhCOH, PhC(NTol)H, and primary
organic amides. A part of the work was communicated previ-
ously.23
As part of our program in this area,4,11,20 we reported
preliminary results for the reaction of the new cyclopentadienyl-
amidinate systems Ti(η-C5Me5)(NR){MeC(NiPr)2}23 (R ) tBu
or Ar (2,6-C6H3Me2)) with CO2.23 Cycloaddition reactions of
titanium imides with CO2 have been reported for a number of
other systems,24-27 but the cyclopentadienyl-amidinate systems
were especially interesting because the reaction products
ultimately formed showed a marked dependency on the imido
Results and Discussion
Synthesis of Cyclopentadienyl-Amidinate Imido Com-
pounds. The half-sandwich tert-butyl imido compounds Ti(η-
C5R5)(NtBu){PhC(NSiMe3)2} (R ) H or Me (5))29,30 have
previously been prepared from the imido-benzamidinate com-
plex Ti(NtBu){PhC(NSiMe3)2}Cl(py)2.31 To develop the chem-
istry of cyclopentadienyl-amidinate imido compounds further,
it was necessary to be able to vary the imido and amidinate
ligand N-substituents, as well as the cyclopentadienyl ligand
substituents. However, our attempts to develop a wider range
of amidinate-imido starting complexes Ti(NR){R2C(NR1)2}-
Cl(py)2 (R2, R1 other than phenyl, SiMe3; R ) tBu or aryl) met
with frustration, the products being ill-defined and rather
capricious in their handling. This is consistent with our previous
report that although reaction of Li[PhC(NSiMe3)2] with Ti(Nt-
Bu)Cl2(py)3 afforded the monomeric benzamidinate compound
Ti(NtBu){PhC(NSiMe3)2}Cl(py)2,31 the corresponding reaction
with Li[MeC(NCy)2] (Cy ) cyclohexyl) gave a poorly soluble,
dimeric product,30 thus showing the sensitivity of the reaction
and products to the particular amidinate ligand employed.
t
NR group. In the case when R ) Bu, CO2 cycloaddition (to
form N,O-bound carbamate complex 1a, Chart 1) was followed
t
by cycloreversion (extrusion of BuNCO) to yield the µ-oxo-
bridged dimer 2, whereas the corresponding reaction for 1b
(R ) Ar) yielded exclusively the double CO2 activation product
3 where a second CO2 molecule has inserted into the carbamate
Ti-N bond of 1b. Motivated by the potential of cyclopenta-
dienyl-amidinate titanium imido complexes to offer additional
variation or control of CO2 reactivity, we recently reported
comprehensive experimental and DFT computational studies of
the reactions of various pendant arm functionalized complexes
(for example 4, Chart 1) with CO2.28 The nature of the pendant
arm affected both the CO2 and isocyanate extrusion reaction
steps.
In this paper we report the synthesis and characterization of
new cyclopentadienyl-amidinate titanium imido complexes,
(21) Odom, A. L. Dalton Trans. 2005, 225-233.
Our presently favored route to cyclopentadienyl-amidinate
imido compounds is summarized in Scheme 1 and starts from
the previously reported32 half-sandwich compounds Ti(η-C5R4-
Me)(NtBu)Cl(py) (R ) Me or H). As proof of method, we found
that reaction of Ti(η-C5Me5)(NtBu)Cl(py) with Li[PhC(N-
SiMe3)2] gave Ti(η-C5Me5)(NtBu){PhC(NSiMe3)2} (5) in 41%
(22) For a very recent review and compilation of leading references in
titanium imido chemistry (covering aspects of molecular and supramolecular
structures and bonding; applications in olefin polymerization; uses in
materials chemistry; transformations involving the TidNR bond itself) see
ref 20.
(23) Guiducci, A. E.; Cowley, A. R.; Skinner, M. E. G.; Mountford, P.
J. Chem. Soc., Dalton Trans. 2001, 1392.
(24) Blake, A. J.; McInnes, J. M.; Mountford, P.; Nikonov, G. I.;
Swallow, D.; Watkin, D. J. J. Chem. Soc., Dalton Trans. 1999, 379.
(25) Dubberley, S. R.; Friedrich, A.; Willman, D. A.; Mountford, P.;
Radius, U. Chem. Eur. J. 2003, 9, 3634.
(29) Stewart, P. J.; Blake, A. J.; Mountford, P. Organometallics 1998,
17, 3271.
(26) Hsu, S.-H.; Chang, C.; Lai, C.-L.; Hu, C.-H.; Lee, H. M.; Lee, G.-
H.; Peng, S.-M.; Huang, J.-H. Inorg. Chem. 2004, 43, 6786.
(27) Boyd, C. L.; Toupance, T.; Tyrrell, B. R.; Ward, B. D.; Wilson, C.
R.; Cowley, A. R.; Mountford, P. Organometallics 2005, 24, 309.
(28) Boyd, C. L.; Clot, E.; Guiducci, A. E.; Mountford, P. Organo-
metallics 2005, 24, 2347.
(30) Stewart, P. J.; Blake, A. J.; Mountford, P. J. Organomet. Chem.
1998, 564, 209.
(31) Stewart, P. J.; Blake, A. J.; Mountford, P. Inorg. Chem. 1997, 36,
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(32) Dunn, S. C.; Mountford, P.; Robson, D. A. J. Chem. Soc., Dalton
Trans. 1997, 293.

Cyclopentadienyl-Amidinate Titanium Imido Compounds
Organometallics, Vol. 25, No. 5, 2006 1169
Scheme 2. Reactions of Cyclopentadienyl-Amidinate
tert-Butyl Imido Compounds with CS2 and COS
Figure 1. Displacement ellipsoid plot (25% probability) of Ti(η-
C5Me5)(NAr){MeC(NiPr)2} (9). H atoms are omitted for clarity.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for
Ti(η-C5Me5)(NAr){MeC(NiPr)2} (9)a
Ti(1)-N(1)
Ti(1)-N(2)
Ti(1)-N(3)
2.094(2)
2.099(2)
1.738(2)
Ti(1)‚‚‚Cpcent
C(1)-N(1)
C(1)-N(2)
2.085
1.335(4)
1.339(4)
Ti(1)-N(3)-C(9)
Cpcent‚‚‚Ti(1)-N(1)
a Cpcent refers to the C5Me5 ring carbon centroid.
168.9(2)
119.1
Cpcent‚‚‚Ti(1)-N(2)
Cpcent‚‚‚Ti(1)-N(3)
119.5
121.4
to the titanium center, which achieves an overall valence electron
count of 16. As seen previously with the MeC(NiPr)2 ligand,36
the methyl groups of the isopropyl substituents are oriented away
from the backbone methyl group (C(2)), presumably to minimize
intraligand steric repulsions. Although structural data for nearly
100 cyclopentadienyl-amidinate transition metal compounds are
listed in the Cambridge Crystallographic Database, including
ca. 10 for titanium systems in particular,37-41 compound 9 is
the first crystallographically characterized group 4 imido
complex within this family.
yield after high-vacuum sublimation (Scheme 1). This yield is
somewhat lower than the 79% reported for the previous route
starting from LiC5Me5 and Ti(NtBu){PhC(NSiMe3)2}Cl(py)2.30
However, the new benzamidinate and diisopropylacetamidinate
complexes Ti(η-C5Me5)(NtBu){MeC(NiPr)2} (6, 98% yield) and
Ti(η-C5H4Me)(NtBu){R2C(NR1)2} (R1 ) SiMe3, R2 ) Ph (7,
93% yield); R1 ) Me, R2 ) Pr (8, 96% yield)) were obtained
i
The rest of this contribution describes the reactions of the
cyclopentadienyl-amidinate imido complexes with a range of
organic substrates.
in excellent yield.
Since it is known23-25 that the cycloaddition chemistry of
aryl imido complexes can be rather different from that of the
tert-butyl imido homologues, we also targeted aryl imido
compounds with sterically different imido N-aryl substituents,
focusing on the pentamethylcyclopentadienyl-diisopropylaceta-
midinate-supporting ligand set. An arylamine/tert-butyl imide
exchange protocol33 was used, and reaction (Scheme 1) of Ti-
(η-C5Me5)(NtBu){MeC(NiPr)2} (6) with ArNH2 (Ar ) 2,6-C6H3-
Me2) or TolNH2 (Tol ) 4-C6H4Me) at room temperature
afforded the compounds Ti(η-C5Me5)(NR){MeC(NiPr)2} (R )
Ar (9, 95% yield) or Tol (10, 50% yield)).
Reactions with CS2 and COS. As mentioned, our previous
studies of the reactivity of TidNR bonds in cyclopentadienyl-
amidinate complexes have focused exclusively on the reactions
with CO2.23,28 We therefore start our discussion with the
reactions with sulfur-containing analogues of CO2. A number
of reactions of imido compounds with CS2 have been described
previously,25,26,42-44 and the usual reaction pathway is cyclo-
addition followed by extrusion to form the corresponding
isothiocyanate and metal sulfide. Reactions between the tert-
butyl imido compounds 5-8 and CS2 and COS are summarized
in Scheme 2. The corresponding reactions of the aryl imido
The molecular structure of Ti(η-C5Me5)(N-2,6-C6H3Me2)-
{MeC(NiPr)2} (9) determined by single crystal X-ray diffraction
is shown in Figure 1. The compound is monomeric with a three-
legged piano stool geometry and is consistent with the solution
NMR data. The selected bond distances and angles listed in
Table 1 are within the previously reported ranges34,35 for
titanium(IV) complexes of the three types of ligand present.
The reasonably linear TidN-Ar linkage (Ti(1)-N((3)-C(9)
) 168.9(2)°) suggests that the arylimido nitrogen (N(3)) is
formally sp-hybridized and able to act as a four-electron donor
(36) Keaton, R. J.; Jayaratne, K. C.; Henningsen, D. A.; Koterwas, L.
A.; Sita, L. J. Am. Chem. Soc. 2001, 123, 6197.
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mann, F. T.; Teuben, J. H.; Green, M. L. H. J. Chem. Soc., Dalton Trans.
1995, 217.
(38) Babcock, J. R.; Incarvito, C.; Rheingold, A. L.; Fettinger, J. C.;
Sita, L. Organometallics 1999, 18, 5729.
(39) Koterwas, L. A.; Fettinger, J. C.; Sita, L. Organometallics 1999,
18, 4183.
(40) van Meerendonk, W. J.; Schroder, K.; Brussee, E. A. C.; Meetsma,
A.; Hessen, B.; Teuben, J. H. Eur. J. Inorg. Chem. 2003, 427.
(41) Sotoodeh, M.; Leichtweis, I.; Roesky, H. W.; Noltemeyer, M.;
Schmidt, H.-G. Chem. Ber. 1993, 126, 913.
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B. O. Polyhedron 1993, 13, 485.
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Shishkin, O. V. J. Chem. Soc., Dalton Trans. 1997, 1549.
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Comput. Sci. 1996, 36, 746.
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(44) Wang, H.; Chan, H.; Xie, Z. Organometallics 2005, 24, 3772.

1170 Organometallics, Vol. 25, No. 5, 2006
Guiducci et al.
Table 2. Selected Distances (Å) and Angles (deg) for
Scheme 3. Reactions of Ti(η-C5Me5)(NR){MeC(NiPr)2} (R
) Ar (9) or Tol (10))
[Ti(η-C5Me5)(µ-S){PhC(NSiMe3)2}]2 (11) and
[Ti(η-C5H4Me)(µ-S){PhC(NSiMe3)2}]2 (13)a
compound 11
Ti(1)-N(1)
compound 13
2.193(3)
2.259(1)
Ti(1)-N(1)
2.135(3)
2.197(3)
2.304(1)
2.363(1)
2.061
Ti(1)-N(1B)
Ti(1)-S(1)
Ti(1)-S(1)
Ti(1)-S(1B)
Ti(1)-Cpcent
Ti(1)-Cpcent
2.101
111.2
Cpcent-Ti(1)-N(1)
Cpcent-Ti(1)-N(1)
Cpcent-Ti(1)-N(1B)
Cpcent-Ti(1)-S(1)
Cpcent-Ti(1)-S(1B)
Ti(1)-S(1)-Ti(1B)
112.5
108.2
119.3
110.1
Cpcent-Ti(1)-S(1)
113.6
Ti(1)-S(1)-Ti(1C)
92.44(7)
91.73(4)
a Cpcent refers to the C5Me5 or C5H4Me ring carbon centroid.
Unexpectedly, the reaction of Ti(η-C5Me5)(NtBu){MeC-
(NiPr)2} (6) with an excess of CS2 gave [Ti(η-C5Me5)(µ-S)-
{N(iPr)C(Me)N(iPr)C(S)S}]2 (18, Scheme 2) in 80% isolated
yield after 10 days at room temperature. Compound 18 is formed
by net CS2 insertion into a Ti-Namidinate bond as well as attack
at the TidNtBu bond (CS2 cycloaddition/tBuNCS extrusion).
The NMR and IR spectra and combustion elemental analysis
of 18 were consistent with the proposed structure, and the EI
mass spectrum showed the expected parent ion at m/z ) 864
with the correct isotope distribution. When the reaction between
6 and exactly 1 equiv of CS2 was followed by 1H NMR in C6D6,
compounds 9 and 10 are summarized in Scheme 3 and discussed
below.
t
ca. 50% conversion to 18 and BuNCS was observed, and the
The reactions with CS2 and COS were all slower than the
ones reported previously for CO2,23,28 with those for CS2 being
the slowest. For example, when followed by 1H NMR in C6D6,
the reaction of Ti(η-C5H4Me)(NtBu){PhC(NSiMe3)2} (7) with
COS (to form 13) was complete within 14 h, whereas that with
CS2 took 4-5 days under otherwise identical conditions. These
relative rates of reaction are consistent with previous reports
for reactions of multiple bonds with these substrates.45 Second,
for a given substrate, the more sterically encumbered C5Me5-
supported compounds reacted at the slowest rates. With the
exception of that between 6 and CS2 (see below), the reactions
of 5-8 with CS2 formed the dimeric sulfido-bridged complexes
[Ti(η-C5R4Me)(µ-S){R2C(NR1)2}]2 (Scheme 2) and tert-butyl
isothiocyanate. The compounds 11, 13, and 14 were isolated
on a preparative scale (30-68% yield), and 11 and 13 were
crystallographically characterized (see below). Compound 12
(Scheme 2) could not be obtained this way and was made on a
preparative scale from 6 and COS. NMR tube scale reactions
between COS and 5, 7, and 8 showed that the corresponding
µ-sulfido dimers (and tBuNCO) were also quantitatively formed.
The reactions to form 11-14 are assumed to proceed via a
cycloaddition-extrusion mechanism, although no NMR evi-
dence for the likely (di)thiocarbamate intermediates Ti(η-C5R4-
Me){N(tBu)C(E)S}{R2C(NR1)2} (E ) S or O) was found. The
reactions of COS with 5-8 were exclusively selective for
CdS bond cleavage and, when followed by 1H NMR, showed
no evidence for the formation of tBuNCS or the corresponding
oxo-bridged dimers [Ti(η-C5R4Me)(µ-O){R2C(NR1)2}]2 (R1 )
rest of the 6 remained unreacted. No reaction was observed
between the dimeric sulfide [Ti(η-C5Me5)(µ-S){MeC(NiPr)2}]2
(12, prepared from 6 and COS) and CS2 over three weeks. These
observations suggest that formation of 18 proceeds via initial
CS2 insertion into a Ti-Namidinate followed by a relatively fast
cycloaddition to the TidNtBu bond (or vice versa), extrusion
of tBuNCS, and dimerization of the so-formed transient terminal
monomeric sulfide Ti(η-C5Me5)(S){N(iPr)C(Me)N(iPr)C(S)S}.
48
Although the insertion of CS2 into a metal-Namidinate or
related49 bond is precedented, it is not apparent why the reaction
of 6 with CS2 differs from those of the other imides studied.
The molecular structures of [Ti(η-C5Me5)(µ-S){PhC(NSi-
Me3)2}]2 (11) and [Ti(η-C5H4Me)(µ-S){PhC(NSiMe3)2}]2 (13)
are compared in Figure 2, and selected distances and angles
are listed in Table 2. The structures are very similar and reveal
the mutual trans arrangement of the cyclopentadienyl rings as
well as the dimeric nature of the products, which may be
described as edge-shared, four-legged piano stools. The distances
and angles are within previously reported ranges for the ligands
present.34,35 The slightly longer Ti-Cpcent distance in 11 may
be attributed to greater steric influence of the C5Me5 ring, as
may the slightly longer Ti(1)-N(1) distance compared to the
average value in 13. The observation of longer average Ti-S
distances in 13 may be a consequence of these other shorter
bond distances (i.e., Ti-Cpcent, Ti-N) leading to more repulsion
between the metal centers (note also that the cyclopentadienyl
ring methyl groups in 13 are oriented over the Ti2(µ-S)2 moiety,
toward the adjacent Ti{PhC(NSiMe3)2} moiety).
i
SiMe3, R2 ) Ph, R ) Me (15) or H (16);46,47 R1 ) Pr, R2 )
Scheme 3 summarizes the reactions of the aryl imido
compounds Ti(η-C5Me5)(NR){MeC(NiPr)2} (R ) Ar (9) or Tol
(10)) with CS2 and COS. These were all faster than those of
the tert-butyl imides 6 and 8. Again, the reactions with CS2
were slower that those with COS, and the tolyl imido compound
Me, R ) Me (2)23 or H (17)46,47). Selective CdS bond cleavage
of COS in reactions with multiply bonded compounds is
precedented.45
(45) Housemekerides, C. E.; Ramage, D. L.; Kretz, C. M.; Shontz, J.
T.; Pilato, R. S.; Geoffroy, G. L.; Rheingold, A. L.; Haggerty, B. S. Inorg.
Chem. 1992, 31, 4453.
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(46) Guiducci, A. E. D. Phil. Thesis, University of Oxford, 2002.
(47) Guiducci, A. E.; Boyd, C. L.; Clot, E.; Mountford, P., manuscript
in preparation.
Chem. 1987, 334, 399.
(49) Dinger, M. B.; Henderson, W. J. Chem. Soc., Dalton Trans. 1998,
1763.

Cyclopentadienyl-Amidinate Titanium Imido Compounds
Organometallics, Vol. 25, No. 5, 2006 1171
formation of 12 and ArNCO on decomposition of 20, supports
the N,S-bound thiocarbamate isomers proposed in Scheme 3.
The (di)thiocarbamate intermediates formed from the tolyl imide
10 and CS2 or COS extruded TolNCS or TolNCO (forming 12)
much more quickly than 19 or 20. NMR tube scale reactions
of 10 showed that the extrusion products had started to be
formed in significant amounts even before all of 10 had finished
reacting, and the likely (di)thiocarbamate intermediates could
not be isolated on a preparative scale.
In no cases were products of a second CS2 or COS insertion
into a Ti-Ncarbamate bond of 19 or 20 seen, in contrast to the
corresponding reactions with CO2 (e.g., reaction of 1b (Chart
1) to form dicarboxylate 323). It is interesting that the more
sterically crowded intermediate carbamates 19 and 20 (formed
from 9) are more stable to isocyanate extrusion than their
homologues formed from 10. This recurrent theme (vide infra
and ref 28) in the reactions of cyclopentadienyl-amidinate
systems contrasts with reports for other systems12,43 and may
reflect difficulties associated with accessing the appropriate
transition state for the more sterically crowded cyclopentadienyl-
amidinate systems.50
Reactions with Organic Isocyanates and Carbodiimides.
Reactions with Isocyanates (1:1 ratio). The reactions of metal
imido compounds (L)MdNR with isocyanates R′NCO are well
established and in the first instance can lead to either N,O- or
N,N-bound ureate complexes, (L)M{N(R)C(NR′)O} or (L)M-
{N(R)C(O)N(R′)}. These can often be isolated24,25,51-59 but can
also extrude either a molecule of carbodiimide (RNdCdNR′)
to form the corresponding metal oxo compound44,55-57 or a
molecule of a different isocyanate (RNCO), leading to a new
metal imido compound (L)MdNR′.26,53,58 In addition, we have
previously shown that certain first-formed titanium ureate
species can reversibly insert a further equivalent of isocyanate,
forming transient N,N-bound biuret species (i.e., compounds
analogous to 3 (Chart 1) but with the metal-bound O atoms
replaced by NR).24 Later transition metal N,N-bound biuret
complexes have also been formed (sometimes reversibly) from
the reactions of metal ureate complexes with isocyanates,49,60-62
although in these cases metal imido compounds were not the
precursors to the ureates themselves. Given their interesting
reactions with CO2 and the rich chemistry of metal imido
(50) For example, structurally characterized pentamethylcyclopentadienyl
complexes Ti(η-C5Me5){NtBuC(O)O}{Me3SiNC(Ph)N(CH2)nNMe2} (formed
from CO2 and 4) undergo tBuNCO extrusion over 1-2 h at room
temperature, whereas the monomethylcyclopentadienyl homologues Ti(η-
C5H4Me){NtBuC(O)O}{Me3SiNC(Ph)N(CH2)nNMe2} undergo first-order,
concentration-independent decay rapidly above -25 °C.28
(51) Michelman, R. I.; Bergamn, R. G.; Andersen, R. A. Organometallics
1993, 12, 2741.
(52) Legzdins, P.; Phillips, E. C.; Rettig, S. J.; Trotter, J.; Veltheer, J.
E.; Yee, V. C. Organometallics 1992, 11, 3104.
(53) Forster, G. D.; Hogarth, G. J. Chem. Soc., Dalton Trans. 1993, 2539.
(54) Blake, A. J.; Mountford, P.; Nikonov, G. I.; Swallow, D. Chem.
Commun. 1996, 1835.
Figure 2. Displacement ellipsoid plots (25% probability) of [Ti-
(η-C5Me5)(µ-S){PhC(NSiMe3)2}]2 (11, top) and [Ti(η-C5H4Me)-
(µ-S){PhC(NSiMe3)2}]2 (13, bottom). H atoms are omitted for
clarity.
10 reacted more quickly than the more sterically crowded 9.
NMR tube scale experiments showed that the ultimate products
of these reactions were the sulfide-bridged dimer 12 and either
RNCS (CS2 reactions; R ) Ar for 9 or Tol for 10) or RNCO
(COS reactions). At intermediate stages of reaction resonances
attributable to likely (di)thiocarbamate intermediates were
observed (Scheme 3). In preparative scale reactions of 9 with
CS2 and COS the compounds Ti(η-C5Me5){N(Ar)C(S)S}{MeC-
(NiPr)2} (19, 60% yield) and Ti(η-C5Me5){N(Ar)C(O)S}{MeC-
(NiPr)2} (20, 70% yield), respectively, could be isolated. The
IR spectrum of 20 showed a ν(CdO) band at 1672 cm-1, which
was absent in the IR spectrum of 19. This, and the quantitative
(55) Walsh, P. J.; Hollander, F. J.; Bergman, R. G. Organometallics 1993,
12, 3705.
(56) Birdwhistell, K. R.; Boucher, T.; Ensminger, M.; Harris, S.; Johnson,
M.; Toporek, S. Organometallics 1993, 12, 1023.
(57) Thorman, J. L.; Guzei, I. A.; Young, V. G.; Woo, L. K. Inorg. Chem.
1999, 38, 3814.
(58) Danopoulos, A. A.; Wilkinson, G.; Sweet, T. K. N.; Hursthouse,
M. B. J. Chem. Soc., Dalton Trans. 1995, 2111.
(59) Hanna, T. E.; Keresztes, I.; Lobkovsky, E.; Bernskoetter, W. H.;
Chirik, P. J. Organometallics 2004, 23, 3448.
(60) Paul, F.; Fischer, J.; Ochsenbein, P.; Osborn, J. A. Angew. Chem.,
Int. Ed. Engl. 1993, 32, 1638.
(61) Dinger, M. B.; Henderson, W. J. Organomet. Chem. 1998, 557,
231.
(62) Holland, A. W.; Bergman, R. G. J. Am. Chem. Soc. 2002, 124, 9010.

1172 Organometallics, Vol. 25, No. 5, 2006
Guiducci et al.
Scheme 4. Reactions of Arylimido Compounds Ti(η-C5Me5)(NR){PhC(NiPr2)2} (R ) Ar (9) or Tol (10)) with tert-Butyl and
Aryl Isocyanates
compounds with isocyanates in general, we decided to explore
in detail reactions of cyclopentadienyl-amidinate titanium imido
compounds with isocyanates.
formed, it is likely that N,O-bound ureate intermediates are
involved, but no resonances for such species were observed
except in the reaction of the least sterically crowded tert-butyl
imide, namely, 8. However, these were minor peaks compared
to the starting compound 8 and µ-oxo product 17, and it was
not deemed feasible to attempt to isolate this compound on a
preparative scale. Structurally characterized N,O-bound ureate
products are described in due course below.
The reactions of 6 or 7 with ArNCO were noticeably faster,
with half-lives of ca. 24 and 12 h, respectively, for consumption
of the starting imides. The slightly faster rate of reaction may
reflect the reduced steric factors associated with ArNCO in
t
The tert-butyl imido compounds gave different final products
comparison with BuNCO and perhaps the different electro-
from the aryl imido analogues. Equation 1 summarizes the NMR
tube scale (C6D6) reactions of compounds 5-8 with BuNCO
philicities of the central carbon in these substrates. As men-
tioned, the ultimate products of the reactions are the oxo dimers
2 and 16 and BuNCNAr. Additional resonances attributed to
t
t
and of 6 and 7 with ArNCO. In all cases the products were the
known63,64 carbodiimide tBuNCNtBu or tBuNCNAr (identified
by their GC-MS and/or 1H NMR spectra) and the corresponding
µ-oxo-bridged dimer 2 or 15-17. The reactions with tBuNCO
were very slow indeed at room temperature, with half-lives
ranging from 4 to 18 days (this being for the reaction of 5 with
tBuNCO). The reactions are considerably slower that those of
6 with CO2, in which instantaneous formation of carbamate 1a
(Chart 1) occurs.23 Since µ-oxo-bridged dimers are ultimately
N,O-bound ureate intermediates Ti(η-C5R4Me){N(tBu)C(NAr)O}-
{MeC(NR1)2} were seen at intermediate reaction times. How-
ever, these were always alongside those of the starting materials
and final reaction products, and again no attempt was made to
isolate them on a preparative scale. The ready collapse of all
these presumed cycloaddition products to the final µ-oxo
products in eq 1 parallels the behavior found with CO2, CS2,
and COS. We therefore turned our attention to reactions of aryl
imido compounds, which we hoped would give more stable
metallocyclic products. Scheme 4 summarizes the reactions of
the aryl imides 9 and 10 with various isocyanates. Variation of
(63) Chang, H.-H.; Weinstein, B. J. Chem. Soc., Perkin Trans. 1 1977,
14, 1601.
(64) Royo, P.; Sanchez-Nieves, J. J. Organomet. Chem. 2000, 597, 61.

Cyclopentadienyl-Amidinate Titanium Imido Compounds
Organometallics, Vol. 25, No. 5, 2006 1173
the imido N-substituents 2,6-C6H3Me2 and p-tolyl provided for
t
some control of steric influence. Reaction of 9 with BuNCO
ultimately gave quantitative conversion to the µ-oxo dimer 2
t
and BuNCNAr64 after ca. 12 h. In contrast to the reactions of
5-8, however, conversion of 9 to the N,O-bound ureate Ti(η-
C5Me5){N(Ar)C(NtBu)O}{MeC(NiPr)2} (21) intermediate was
complete after ca. 4 h and before significant decay to 2 and
tBuNCNAr had occurred, thus allowing its isolation as a sticky
oil in 27% yield. The tolyl imido compound 10 also reacted
t
with BuNCO to form µ-oxo-bridged dimer 2 (together with
tBuNCNTol). However, although the initial reaction to form the
likely intermediate Ti(η-C5Me5){N(Tol)C(NtBu)O}{MeC-
(NiPr)2} was faster than for the corresponding reaction of 9,
the subsequent extrusion reaction to form 2 was also faster
(complete within ca. 3 h) and it was not possible to isolate this
intermediate. Again (as noted above) it appears that the bulkier
N-Ar substituent in 21 confers slightly greater stability on the
intermediate cycloaddition species than the smaller N-Tol
substituent.
The instability of 21 in solution hindered further purification,
but its NMR and IR spectra support the structure shown in
Scheme 4. The MeC(NiPr)2 ligand isopropyl groups appear as
1
two sharp apparent septets and four doublets in the H NMR
spectrum. The ortho-methyl groups of the Ar N-substituent are
sharp and inequivalent at room temperature, consistent with
restricted rotation about the N-Cipso bond and thus this group
being attached to the metal-bound nitrogen in a rather crowded
position (rather than being attached to the less crowded exocyclic
CdN nitrogen). These spectroscopic features are analogous to
the structurally characterized compounds 22 and 23 (Scheme
4) described below, which only differ in having Ar or Tol groups
in place of the tBu group in 21. A band at 1652 cm-1 in the IR
spectrum of 21 is consistent with a CdNtBu functional group.
Finally we note that the resonances for 21 are not the same as
those tentatively assigned to the putative intermediate Ti(η-C5-
Me5){N(tBu)C(NAr)O}{MeC(NiPr)2} (an isomer of 21) formed
in the reaction of 6 with ArNCO (eq 1).
In contrast to the instability of 21, the cycloaddition products
22-25 (Scheme 4) formed between 9 and 10 and TolNCO or
ArNCO were stable for weeks at room temperature (decomposi-
tion to unidentified mixtures occurred only at elevated temper-
atures). The compounds 23 and 24 are isomers of each other
(the structure of 23 was confirmed by X-ray crystallography;
see below) but do not interconvert or equilibrate in solution
even after several weeks. This is in contrast to Woo’s N,O-
ureate compound Zr{N(-2,6-C6H3iPr2)C(NtBu)O}(TTP) (formed
Figure 3. Displacement ellipsoid plots (20% probability) of Ti-
(η-C5Me5){N(Ar)C(NR)O}{MeC(NiPr)2} (R ) Ar (22, top) or Tol
(23, bottom)). H atoms are omitted for clarity.
The IR data for the new compounds are consistent with the
proposed structures and feature ν(CdN) bands in the range
1609-1616 cm-1 (somewhat lower than the corresponding band
in 21). The ν(CdO) band in the corresponding CO2 cycload-
dition product Ti(η-C5Me5){N(Ar)C(O)O}{MeC(NiPr)2} (1b)
was higher, as expected (ν(CdO) ) 1669 cm-1).23 The
ν(CdO) bands in the N,N-bound ureates Ti{N(Ph)C(O)N(R)}-
(Me4taa) (H2Me4taa ) tetramethyldibenzotetraaza[14]annulene;
i
t
from Zr(N-2,6-C6H3 Pr2)(TTP) and BuNCO), which slowly
i
isomerizes to Zr{N(tBu)C(N-2,6-C6H3 Pr2)O}(TTP) (H2TTP )
meso-tetra-p-tolylporphyrin) over a number of weeks.57
The NMR spectra of 22-25 show the absence of molecular
symmetry (inequivalent iPr groups for the MeC(NiPr)2 ligand).
For 22 and 25 this is good evidence for the proposed N,O-
bound complexes (alternative isomers with N,N-bound ureate
ligands would be Cs symmetrical species); the symmetry of the
N,N-bound ureate isomers of 23 and 24, however, would also
be C1. The methyl groups of the Ar moiety in 23 appear as two
sharp resonances, consistent with this group being rather
sterically hindered (see also the crystal structure of this
compound below). In its isomer 24, however, the two methyl
groups appear as a singlet (relative intensity 6 H), showing that
the exocyclic CdNAr site is significantly less crowded. In
structurally characterized 22 one Ar substituent exhibits hindered
rotation (presumably the one closest to the titanium) and the
other does not.
R ) Ph or Tol) appear in the range 1626-1630 cm-1 24
.
Conclusive evidence of the N,O-coordination is provided by
the X-ray structures of 22 and 23, which are shown in Figure
3. Selected distances and angles are given in Table 3.
The molecular structures of 22 and 23 confirm those proposed
in Scheme 4. The four-legged piano stool molecules contain
η5-bound C5Me5 and bidentate MeC(NiPr)2 ligands along with
the expected N,O-bound ureate ligands. The associated distances
and angles are very similar for the two compounds, as expected,
since they differ only in the identity of the exocyclic N(4)
substituent. However, the orientation of these rings differs

1174 Organometallics, Vol. 25, No. 5, 2006
Guiducci et al.
coordination mode. We also found that Ti(NtBu)(Me4taa) reacts
with OCN-4-C6H4NO2 to give an N,N-bound ureate product,
whereas with BuNCO an N,O-bound ureate was formed,
presumably to minimize steric repulsions between tert-butyl
groups and the Ti(Me4taa) moiety.24 Chirik recently reported
that Ti{η-C5H3(SiMe3)2}2(NSiMe3) forms an N,O-bound ureate
derivative on reaction with Me3SiNCO.59
Table 3. Selected Distances (Å) and Angles (deg) for
Ti(η-C5Me5){N(Ar)C(NR)O}{MeC(NiPr)2} (R ) Ar (22) or
Tol (23))a
t
parameter
compound 22
compound 23
Ti(1)-N(1)
2.149(3)
2.027(3)
1.995(3)
1.981(3)
2.094
2.024(5)
2.150(5)
1.994(4)
1.973(4)
2.106
Ti(1)-N(2)
Ti(1)-N(3)
Ti(1)-O(1)
Ti(1)-Cpcent
C(9)-N(4)
If steric factors are indeed important in the reactions shown
in Scheme 4, then the observation that even the least sterically
crowded product 25 (Scheme 4) possesses an N,O-bound ureate
ligand would suggest that the C5Me5/MeC(NiPr)2 supporting
ligand set is relatively sterically demanding. To probe this
aspect, DFT (density functional theory) calculations were carried
out on the simple hypothetical models Ti(η-C5H5){N(Me)C-
(NMe)O}{MeC(NMe)2} (I, N,O-bound ureate) and Ti(η-C5H5)-
{N(Me)C(O)N(Me)}{MeC(NMe)2} (II, N,N-bound ureate).
Details of the calculations are provided in the Experimental
Section and Supporting Information. The N,O-bound isomer I
was less stable than II, but by only 11.7 kJ‚mol-1 (electronic
energies). Even the sterically unencumbered model system II
is apparently strained, as indicated by inequivalent Cpcent-Ti-
1.283(5)
1.283(7)
N(1)-Ti(1)-N(2)
N(3)-Ti(1)-O(1)
Cpcent-Ti(1)-N(1)
Cpcent-Ti(1)-N(2)
Cpcent-Ti(1)-N(3)
Cpcent-Ti(1)-O(1)
C(9)-N(4)-C(10)
C(9)-N(4)-C(10)-C(15)
63.83(13)
66.84(12)
112.2
114.7
136.1
104.1
119.0(3)
109.3
63.8(2)
66.6(2)
115.2
111.7
135.7
105.4
121.5(4)
14.4
a Cpcent refers to the C5Me5 ring carbon centroid.
significantly. For 22 the aryl ring lies approximately perpen-
dicular to the {Ti(1)O(1)C(9)N(3)} titanocyclic core (dihedral
angle C(9)-N(4)-C(10)-C(15) ) 109.3°), whereas in 23 the
tolyl ring is nearly coplanar with the titanocycle (dihedral angle
C(9)-N(4)-C(10)-C(15) ) 14.4°). This is due to the presence
of the ortho-methyl substituents in 22. However, since these
Nureate angles of 140.3° and 109.2° (cf. a Cpcent-Ti-Nureate angle
of 125.9° and Cpcent-Ti-O angle of 112.3° in I). Similarly,
the Ti-Namidinate distances of 2.035 and 2.190 Å in II are
significantly more different than those in I (2.060 and 2.120
Å). The DFT results imply that increased crowding in cyclo-
pentadienyl-amidinate-supported ureate complexes would lead
to N,O-bound isomers.
1
methyls appear as a singlet in the H and 13C NMR spectra
(vide supra), the barrier to rotation about the N(4)-Cipso bond
must be relatively small. The average distances and angles
subtended at Ti(1) in the two structures are within the usual
ranges,34,35 and those to the C5Me5 and amidinate ligands are
comparable to the ones found in the starting imide 9 and the
dicarboxylate Ti(η-C5Me5){OC(O)N(Ar)C(O)O}{MeC(NiPr)2}
(3).23 However, within both 22 and 23 the individual
Ti-Namidinate distances are significantly different (∆(Ti-N) )
0.122(6) and 0.126(10) Å), with the bond cis to the carbamate
N-Ar moiety being longer. This is attributed to steric effects of
the bulky aryl substituent. The Cpcent-Ti(1)-N(3) angles (av
135.9°) are significantly larger than the Cpcent-Ti(1)-O(1) (av
104.8°) angles, and this also reflects the steric influence of the
bulky Ar substituent at N(3). This aryl ring lies perpendicular
to the {Ti,N,C,O} titanocycle core and is consistent with the
NMR spectra, which showed two resonances for the individual
ortho-methyl groups. The greater barrier to rotation about the
N(3)-Cipso bond in 22 compared to rotation about N(4)-Cipso
(as implied by the solution NMR data) is consistent with the
greater steric crowding around the former and the higher
coordination number of N(3) compared to N(4).
Multiple Coupling of Heterocumulenes. As mentioned, the
N-aryl-substituted carbamate complex 1b (Chart 1) reacts with
further CO2 to form the novel dicarboxylate 3.23 Furthermore,
certain metal N,N-bound ureates undergo insertion of isocyan-
ates into one of the metal-nitrogen bonds.24,49,60-62 We therefore
decided to study the reactions of the new N,O-bound ureates
with additional isocyanate or CO2. The new chemistry is
summarized in Schemes 4 and 5.
Reaction of Ti(η-C5Me5){N(Tol)C(NTol)O}{MeC(NiPr)2}
(25) with TolNCO afforded the new compound Ti(η-C5Me5)-
{OC(NTol)N(Tol)C(NTol)O}{MeC(NiPr)2} (26) in 51% iso-
lated yield. The same compound was also formed directly from
Ti(η-C5Me5)(NTol){MeC(NiPr)2} (10) and TolNCO (2 equiv)
in C6D6. Unfortunately we were not able to grow diffraction-
quality crystals of 26 or any of the related products (Scheme 5)
described below. The NMR spectra of 26 suggest molecular Cs
symmetry and feature one isopropyl group environment (two
inequivalent diastereotopic Me groups) and two p-tolyl groups
in a 2:1 ratio. Although in principle these data are consistent
with the presence of either an O,O- or N,N-bound C2O2(NTol)2-
NTol biuret ligand, the O,O-bound isomer depicted for 26 is
favored on the basis of further spectroscopic data. First, no NOE
interactions were found between the tolyl group hydrogens and
those of the C5Me5/MeC(NiPr)2 ligand set. Second, the IR
spectrum shows two new bands at 1655 and 1609 cm-1
(assigned to the in- and out-of-phase ν(CdN) modes (A′ and
A′′), respectively), which differ significantly from the in- and
out-of-phase ν(CdO) modes found for the dicarboxylate 3 (1694
and 1656 cm-1).23
Although only one other crystallographically characterized
ureate complex of titanium has been reported,25 they are in
general well established (a further 10 such structures for other
metals are recorded in the Cambridge Structural Database34,35).
However, only two crystallographically characterized N,O-ureate
complexes have been reported for any metal, namely, Woo’s
Zr{N(-2,6-C6H3 Pr2)C(NtBu)O}(TTP) and its isomer Zr-
i
{N(tBu)C(N-2,6-C6H3 Pr2)O}(TTP).57
i
The factors controlling the preferred ureate ligand coordina-
tion mode may be rather finely balanced. Thus while Zr(N-
2,6-C6H3 Pr2)(TTP) reacts with tBuNCO to form the N,O-bound
i
ureate complex Zr{N(-2,6-C6H3 Pr2)C(NtBu)O}(TTP),57 we
i
i
found that the closely related Zr(N-2,6-C6H3 Pr2)(py)(Me4taa)
(with the same imido N-substituent) reacts with the same
isocyanate to give the structurally authenticated N,N-bound
ureate Zr{N(-2,6-C6H3 Pr2)C(O)N(tBu)}(Me4taa) as the only
i
observed product.24 Since Me4taa provides a more “open”
zirconium coordination site than TTP, it would appear that steric
factors may be important in selecting the preferred ureate

Cyclopentadienyl-Amidinate Titanium Imido Compounds
Organometallics, Vol. 25, No. 5, 2006 1175
Scheme 5. Cross-Coupling Reactions with Heterocumulenes
Biuret and related compounds with two different hetercumu-
lene residues can be prepared as shown in Scheme 5. NMR
tube scale reaction between 24 and TolNCO or 25 and ArNCO
formed the same O,O-bound biuret product, namely, Ti(η-C5-
Me5){OC(NTol)N(Tol)C(NAr)O}{MeC(NiPr)2} (27). The reac-
tion starting from 24 was complete within 5 min, whereas that
starting from 25 required ca. 2 h. Compound 27 was isolated
in 81% yield on a preparative scale starting from 24. The NMR
and IR data for 27 are consistent with the non-Cs-symmetric
structure illustrated.
The totally regioselective cross-coupling of aryl isocyanates
and CO2 can be also achieved. NMR tube scale reactions showed
that the sequential treatment of 10 with TolNCO and CO2 (or
vice versa) led exclusively to a common product, Ti(η-C5Me5)-
{OC(O)N(Tol)C(NTol)O}{MeC(NiPr)2} (28) via 25 or the
carbamate Ti(η-C5Me5){N(Tol)C(O)O}{MeC(NiPr)2} (29),46,47
respectively. The NMR spectra for 28 (obtained in 55% isolated
yield from 29 and TolNCO) featured two inequivalent isopropyl
and para-tolyl groups as expected, and the IR spectrum showed
bands at 1681 and 1618 cm-1 assigned to ν(CdO) and
ν(CdN), respectively. We were also able to prepare the mixed-
heterocumulene compound 30 (with different biuret N-substit-
uents) from 29 and ArNCO in 65% isolated yield. The IR
spectrum showed bands at 1680 and 1620 cm-1, again assigned
to ν(CdO) and ν(CdN), respectively. However, there was no
reaction between the more sterically crowded carbamate Ti(η-
C5Me5){N(Ar)C(O)O}{MeC(NiPr)2} (1b) and either ArNCO or
TolNCO.
As mentioned above, a number of compounds with N,N-
bound biuret ligands have been reported previously,49,60-62,65-67
and several have been crystallographically characterized.60,65-67
However, neither O,O-bound biuret ligands or the related mono-
carboxylate ligands in 28 and 30 have been reported before.
The totally selective insertion of RNCO or CO2 into the Ti-N
bonds of the ureate complexes is consistent with previous reports
of M-N versus M-O bond reactivity toward unsaturated
substrates68 and the exclusive formation of O,O-bound dicar-
boxylate complex 3 (Chart 1) from N-aryl carbamate 1b.
The overall “double substrate activation” reactions leading
to 26-28 and 30 are rare in transition metal imido chemistry.
(65) Hoberg, H.; Oster, B. W.; Kruger, C.; Tsay, Y. H. J. Organomet.
Chem. 1983, 252, 365.
(66) Paul, F.; Fischer, J.; Ochsenbein, P.; Osborn, A. J. C. R. Chim. 2002,
5, 267.
(67) Lam, H.-W.; Wilkinson, G.; Hussain-Bates, B.; Hursthouse, M. B.
J. Chem. Soc., Dalton Trans. 1993, 781.

1176 Organometallics, Vol. 25, No. 5, 2006
Guiducci et al.
The first example was for the reaction of Bergman’s Ir(η-C5-
Me5)(NtBu) with C2(CO2Me)2 to form Ir(η-C5Me5){η4-C4(CO2-
Me)4NtBu}.69 Our reports of the reversible insertion of PhNCO
into a Ti-N bond of the imido-derived ureato complex
Ti{N(Ph)C(O)N(Tol)}(Me4taa)24 and the formation of dicar-
boxylate 3 (Chart 1)23 are the only other such examples for
titanium. Bergman has studied in detail the highly selective
sequential coupling of certain alkynes and carbodiimides with
ZrdNR bonds to form six-membered metallacycles.70
Reactions with Carbodiimides. The reactions of group 4
imido compounds with carbodiimides also have been of recent
interest,24,43,62,70-72 especially with regard to new C-N forming
reactions. Me4taa,24 bis(cyclopentadienyl),43,62 and bis(guanidi-
nate)71,72 supporting ligand sets have so far been employed in
this chemistry, and so it was of interest to explore the reactions
of the cyclopentadienyl-amidinate imido systems.
not clear why 31 does not behave in a similar way to release
the unsymmetrical carbodiimide TolNCNAr and form Ti(η-C5-
Me5)(NTol){MeC(NiPr)2} (10) (which in turn could recombine
with TolNCNAr).
Reactions with Non-cumulene NdO, CdO, and CdNR
Functional Groups. In addition to the cumulenes CO2, CS2,
COS, RNCO, and RNCNR, some of the cyclopentadienyl-
amidinate titanium imido compounds also react with nitrosoben-
zene, aldehydes, ketones, imines, and certain organic amides.
Reactions with PhNO. Transition metal-mediated metathesis
reactions of nitroso compounds are relatively rare.73-77 Me-
tathesis reactions of terminal imido compounds (L)nMdNR with
PhNO to form metal oxo species and diazo compounds RNd
NPh have recently been reported for titanium and zirco-
nium.73,76,77
The reactions of 5-10 with carbodiimides were considerably
slower than the corresponding ones with CO2 or isocyanates
(and in some cases did not proceed at all). This probably reflects
the increased steric interactions arising around the metal center
in the target guanidinate complexes. None of the tert-butyl imido
compounds 5-8 reacted with either iPrNCNiPr or TolNCNTol
at room temperature or upon heating. Similarly, 10 also failed
to react with iPrNCNiPr. However, the reactions between 9 and
10 and TolNCNTol proceeded slowly (24 and 1 h, respectively)
at room temperature to form the guanidinate complexes Ti(η-
C5Me5){N(Tol)C(NTol)N(R)}{MeC(NiPr)2} (R ) Ar (31) or
Tol (32)) in ca. 70% isolated yields (eq 2). The NMR and IR
spectra support the proposed structures, with the latter showing
a ν(CdN) band at 1655 cm-1 in both cases. The NMR spectra
of 32 indicated molecular Cs symmetry, showing two p-tolyl
groups in a 1:2 ratio. The spectra for 31 showed two different
p-tolyl groups in a 1:1 ratio and the absence of any molecular
symmetry, as expected for the structure depicted in eq 2.
The reactions between PhNO and the tert-butyl imido
compounds 5 and 6 were monitored by NMR tube scale
reactions (eq 3). In each case complete consumption of PhNO
had occurred after ca. 5 min and resonances attributed to cis-
tBuNdNPh (formed quantitatively) were observed.78 In the
reaction of 5 the appearance of a fine yellow precipitate signaled
the formation of the highly insoluble µ-oxo dimer [Ti(η-C5-
Me5)(µ-O){PhC(NSiMe3)2}]2 (15)46,47 as the organometallic
side-product. In the reaction of 6 the side-product was [Ti(η-
C5Me5)(µ-O){MeC(NiPr)2}]2 (2).23 The reaction between 5 and
PhNO was scaled up in benzene, giving 15 in 53% isolated
yield. Compound 2 could not be isolated in pure form this way
owing to difficulties in separating it from the organic side-
product (both 15 and 2 can also be cleanly prepared by reaction
of 5 or 6 with CO2 in 19 and 70% isolated yield23,46,47). The
diazo species cis-tBuNdNPh is the kinetic product of these
reactions and over several hours underwent the known thermal
rearrangement to trans-tBuNdNPh.79 The initial formation of
cis-tBuNdNPh implies that the first-formed intermediates are
cycloaddition products of the type III (analogous intermediates
have been proposed previously73).
Heating a sample of 31 in C6D6 at 80 °C for 30 min gave
complete conversion to the starting imide Ti(η-C5Me5)(NAr)-
{MeC(NiPr)2} (9) and the symmetrical starting carbodiimide
TolNCNTol. After 24 h at room temperature the slow cyclo-
addition reaction had re-formed 31. Compound 31 is analogous
to Bergman’s zirconocene complex Cp2Zr{N(Tol)C(NTol)N-
i
i
(2,6-C6H3 Pr2)} (formed from Cp2Zr(N-2,6-C6H3 Pr2)(THF) and
TolNCNTol),43 which, on heating at 75 °C, isomerizes to the
Cs symmetrical guanidinate Cp2Zr{N(Tol)C(N-2,6-C6H3 Pr2)N-
i
(Tol)}, most likely via a cycloreversion/cycloaddition process
i
involving transient Cp2Zr(NTol) and TolNCN-2,6-C6H3 Pr2. The
driving force of this isomerization is believed to be relief of
steric strain in the first-formed (asymmetric) metallacycle. It is
(73) Blum, S. A.; Bergman, R. G. Organometallics 2004, 23, 4003.
(74) Pilato, R. S.; Williams, G. D.; Geoffroy, G. L.; Rheingold, A. L.
Inorg. Chem. 1988, 27, 3665.
(75) Herndon, J. W.; McMullen, L. A. J. Organomet. Chem. 1989, 368,
83.
(68) Legzdins, P.; Rettig, S. J.; Ross, K. J. Organometallics 1994, 13,
569.
(69) Glueck, D. S.; Wu, J.; Hollander, F. J.; Bergman, R. G. J. Am. Chem.
Soc. 1991, 113, 2041.
(70) Zuckerman, R. L.; Bergman, R. G. Organometallics 2001, 20, 1792.
(71) Ong, T.-G.; Yap, G. P.; Richeson, D. S. J. Am. Chem. Soc. 2003,
125, 8100.
(72) Ong, T.-G.; Yap, G. P.; Richeson, D. S. Chem. Commun. 2003,
2612.
(76) Thorman, J. L.; Woo, L. K. Inorg. Chem. 2000, 39, 1301.
(77) Thorman, J. L.; Guzei, I. A.; Young, V. G.; Woo, L. K. Inorg. Chem.
2000, 39, 2344.
(78) Grigsby, W. J.; Hascall, T.; Ellison, J. J.; Olmstead, M. M.; Power,
P. P. Inorg. Chem. 1996, 35, 3254.

Cyclopentadienyl-Amidinate Titanium Imido Compounds
Organometallics, Vol. 25, No. 5, 2006 1177
Scheme 6. Reaction of Ti(η-C5Me5)(NTol){PhC(NiPr2)2}
(10) with PhCOPh. Inset: Plot of ln Kdiss vs 1/T (K-1) for the
Dissociation of Ti(η-C5Me5){N(Tol)C(Ph)2O}{PhC(NiPr2)2}
(33) to Ph2CO and 10
It was hoped that use of aryl imido compound 9 or 10 would
lead to more stable intermediates of this type (cf. the reactions
23
with CO2 and RNCO). However, preliminary screening by
NMR tube scale reactions in C6D6 showed the rapid (within
ca. 3 min) consumption of the aryl imido compound in each
case and the formation of µ-oxo-bridged dimers (eq 3).
Resonances attributable to cis- and trans-tBuNdNR (R ) Ar
or Tol)64,80 were again observed, and the expected molecular
ions were also identifed by APCI mass spectrometry.
The metathesis reactions between 5, 6, 9, and 10 and PhNO
follow the trends previously observed.73,76,77 As in the corre-
sponding zirconium chemistry,73,77 the putative metallocyclic
intermediates were not observed. This is consistent with the
inherently weak nature of O-N and N-N single bonds, which
is typically attributed to secondary electron-electron repulsion.81
Reactions with Aldehydes and Ketones. The metathesis
reactions between metal imido compounds and organic carbon-
yls to form ketimines or aldimines via cyclcoaddition reactions
is well-established.2,12,42,44,55,59,76,82-86 Of particular relevance
to our contribution are the reports for titanium44,59,76,83,85 and
zirconocene systems.12,55,82
in these cases (and perhaps also for 7) that concomitant side-
reactions stemming from the enol tautomer of MeCOMe (CH2-
CH(OH)Me) may also or alternatively be occurring. Bergman
has previously shown82 that increased steric bulk in the reactions
of zirconocene imido compounds with organic ketones pos-
sessing enolizable protons afforded amide-enolate complexes.
The reactions between certain cyclopentadienyl-amidinate
titanium imido compounds and representative carbonyl com-
pounds, namely, MeCOMe, PhCOPh, PhCOH, and PhCOMe,
were assessed, mainly by NMR tube scale reactions. Initial
studies focused on the reactions of the tert-butyl imides 5-7
with MeCOMe (eq 4). The reactions of 6 and 7 proceeded at
room temperature (but only slowly, with 6 being the slower of
the two). No reaction was observed between MeCOMe and the
bulkiest imido compound 5 at room temperature, and this
solution was heated at 80 °C. After 4 days all three reactions
showed incomplete conversion of MeCOMe to the correspond-
ing imine MeC(NtBu)Me, which was identified by NMR
spectroscopy.87,88 The organometallic product of the reaction
with 7 was the µ-oxo dimer [Ti(η-C5H4Me)(µ-O){PhC-
(NSiMe3)2}]2,46,47 as would be expected if the mechanism
proceeds via a imide-ketone cycloaddition reaction82 to form a
metallocycle such as Ti(η-C5H4Me){N(tBu)C(Me)2O}{PhC-
(NSiMe3)2} (IV, not observed). Subsequent collapse of this
metallocycle via extrusion of MeC(NtBu)Me would lead to
transient Ti(η-C5Me5)(O){PhC(NSiMe3)2}, which would, in
turn, self-trap to form the observed µ-oxo dimers. The several
organometallic side-products (not isolable) in the reactions of
5 and 6 were not the expected µ-oxo dimers, and it is possible
No reaction occurred between 6 or 9 and PhCOPh in C6D6.
In contrast, reaction with the tolyl imide 10 almost immediately
gave an equilibrium mixture containing 10, PhCOPh, and a new
compound formulated as the cycloaddition product Ti(η-C5Me5)-
{N(Tol)C(Ph)2O}{MeC(NiPr2)2} (33, Scheme 6). No further
change in the relative amounts of 10 and product 33 was seen
after 10 min, but after ca. 9 days the resonances for both the
starting materials and 33 were virtually absent, and those of
the µ-oxo dimer 2 and PhC(NTol)Ph (identified by comparison
with literature NMR data89 and a parent ion in the APCI mass
spectrum) had appeared. Attempts to isolate 33 led to recovered
starting materials, and so this complex was characterized by
1H NMR spectroscopy in situ, which showed the absence of
molecular symmetry, as suggested by two inequivalent isopropyl
substituents, each with diasterotopic methyl groups. Two
inequivalent phenyl group environments were also observed,
consistent with the proposed structure. Since the resonances for
10, PhCOPh, and 33 are all sharp, any exchange between free
and coordinated PhCOPh must be slow on the NMR time scale.
(79) Ege, S. N.; Sharp, R. R. J. Chem. Soc. (B) 1971, 2014.
(80) Mamoru, K.; Suzuki, N.; Ishihara, H. J. Org. Chem. 1999, 64, 6473.
(81) Mingos, D. M. P. Essential Trends in Inorganic Chemistry; Oxford
University Press, 1998.
(82) Lee, S. Y.; Bergman, R. G. J. Am. Chem. Soc. 1996, 118, 6396.
(83) Nugent, W. A.; McKinney, R. J.; Kasowski, V.; Van-Catledge, F.
A. Inorg. Chim. Acta 1982, 65, L91.
(84) Doxsee, K. M.; Farahi, J. B. Chem. Commun. 1990, 1452.
(85) Rocklage, S. M.; Schrock, R. R. J. Am. Chem. Soc. 1980, 102, 7809.
(86) Royo, P.; Sanchez-Nieves, J. J. Organomet. Chem. 2000, 597, 61.
(87) Klusener, P. A. A.; Tip, L.; Brandsma, L. Tetrahedron 1991, 47,
2041.
Potentially 33 could alternatively be formulated as a σ (Lewis
base) adduct between an oxygen lone pair of the ketone and
titanium. To probe this hypothesis, a CD2Cl2 solution of 10 was
(88) Larsen, J.; Jorgensen, K. A. J. Chem. Soc., Perkin Trans. 2 1992,
1213.
(89) Nongkunsarn, P.; Ramsden, C. A. Tetrahedron 1997, 53, 3805.

1178 Organometallics, Vol. 25, No. 5, 2006
Guiducci et al.
cooled to -90 °C in the presence of pyridine (1 equiv). No
complexation was observed. However, when PhCOPh was
added to the mixture and the spectrum again recorded, the
quantitative formation of 33 was observed. Since pyridine is a
superior Lewis base to PhCOPh, these NMR experiments
militate against 33 being a simple Lewis base adduct (as does
the eventual formation of the imine and µ-oxo products).
Warming the mixture to 50 °C (toluene-d8) displaced the
equilibrium completely in favor of the reactants, whereas on
cooling to -40 °C, the mixture was completely converted to
33. The equilibrium constants for dissociation (Kdiss) of 33 were
measured at 5 °C intervals in the range -30 to -10 °C. A plot
of ln Kdiss versus 1/T is shown in the inset to Scheme 6, and the
derived thermodynamic parameters are ∆Hdiss ) 75.1 ( 1.9
kJ‚mol-1 and ∆Sdiss ) 230 ( 10 J‚mol-1‚K-1. The positive
∆Sdiss is in accord with the dissociative process 33 f 10 +
PhCOPh, and the ∆Hdiss value shows that the metallacycle is
reasonably enthalpically favored. Compound 33 is the first
observed cycloaddition product between a TidNR bond and a
ketonic R2CdO bond. The formation of the imine PhC(NTol)-
Ph from 33 suggests that the reactions with MeCOMe described
above could also follow this cycloaddition/extrusion pathway.
Reasoning that steric factors should inhibit the formation of
metallacycles with PhCOPh, we also examined reactions with
PhCOH (again on the NMR tube scale in C6D6, focusing on
the C5Me5/MeC(NiPr)2 systems 6 and 10). Reaction of the tert-
butyl imide 6 with PhCOH was essentially complete within 5
min to form Ti(η-C5Me5){N(tBu)C(Ph)(H)O}{MeC(NiPr2)2}
(34) with only a trace of unreacted imide and aldehyde present
at this stage. The metallocyclic compound 34 quickly (t1/2 ca.
30 min) underwent extrusion to form the known aldimine PhC-
(NtBu)H (identified by comparison with literature NMR data89
and a parent ion in the APCI mass spectrum) and the µ-oxo-
bridged dimer 2. The instability of 34 prevented its isolation
on the preparative scale, and it was characterized by in situ 1H
NMR spectroscopy. The stereochemistry around the C(Ph)H
carbon in the metallocycle is assumed to be the less sterically
hindered alternative (i.e., with the phenyl group oriented away
from the η-C5Me5 ring, as found in the related PhCOMe
cycloaddition product 36 (see below)).
It is not clear why the PhCOPh cycloaddition product 33
undergoes the retrocyclization reaction (Scheme 6) so much
more slowly than 35a/35b, but one possibility could again be
steric hindrance in the more highly crowded metallocycle 33,
making access to the necessary transition state more difficult.
From the reactions with PhCOPh and PhCOH it appeared
that while too much steric hindrance inhibits or prevents the
formation of the cycloaddition products, some stabilization
toward extrusion is gained by increasing steric bulk around the
metallocyle ring. As a further probe of this, we carried out
reactions of 6, 9, and 10 with PhCOMe. No reaction was seen
after 16 h at room temperature for the more sterically crowded
imides 6 and 9. Trace amounts of µ-oxo species were seen
among other unknown products after heating at 80 °C for 24 h.
However, the tolyl imide 10 reacted smoothly with PhCOMe
in C6D6 within 10 min to give greater than 90% conversion to
the cycloaddition product Ti(η-C5Me5){N(Tol)C(Ph)(Me)O}-
{MeC(NiPr2)2} (36). Under otherwise identical conditions the
conversion of 10 to 33 with PhCOPh was ca. 40%. Compound
36 is relatively stable toward imine extrusion, and the reaction
mixture remained effectively unchanged for at least 1 h. After
16 h ca. 25% conversion to the anticipated metathesis products
PhC(NTol)Me and the µ-oxo dimer 2 was observed. The
somewhat higher stability of 36 compared to that of Ti(η-C5-
Me5){N(Tol)C(Ph)(H)O}{MeC(NiPr2)2} (35a/35b, almost com-
plete extrusion after 1 h) allowed its isolation as a brown wax
in 57% yield on the preparative scale (the intrinsic instability
and waxy nature prevented us from obtaining an analytically
1
pure sample). The H and 13C NMR data are consistent with
the structure depicted below (the orientation of the C(Me)Ph
group being determined from a ROESY spectrum). The absence
of a ν(CdO) band in the IR spectrum of 36 is further support
for the incorporation of the PhCOMe carbonyl group into the
metallocyclic core.
Reaction of the tolyl imide 10 with PhCOH was also complete
after 5 min, but the reaction was more complicated than for 6.
The 1H NMR spectrum after 5 min showed resonances attributed
to two new metallacyclic products, 35a (major, ca. 80%) and
35b (minor), which are believed to be isomers of each other,
namely, Ti(η-C5Me5){N(Tol)C(Ph)(H)O}{MeC(NiPr2)2}. After
20 min the ratio of the isomers was ca. 1:1 with some µ-oxo
dimer 2 being visible. After 1 h 2 was the dominant organo-
metallic species. The aldimine PhC(NTol)H was the organic
side-product of this reaction (identified by comparison with a
commercial sample). The compounds 35a and 35b are probably
diastereomers (the titanium center and the C(Ph)H carbon both
being stereocenters). Two possible structures are illustrated
below, but the instability of the compounds and the complicated
NMR spectra, which contain a number of overlapping reso-
nances, prevented a more comprehensive assignment.
Reactions with Imines. The metathesis reaction between
terminal imides (L)nMdNR and organic imines of the type R′C-
(NR′′)H to afford the corresponding imide (L)nMdNR′′ and
imine R′C(NR)H is still in the early stages of development.90-97
(90) Meyer, K. E.; Walsh, P. J.; Bergman, R. G. J. Am. Chem. Soc. 1994,
116, 2669.
(91) Meyer, K. E.; Walsh, P. J.; Bergman, R. G. J. Am. Chem. Soc. 1995,
117, 974.
(92) McInnes, J. M.; Mountford, P. Chem. Commun. 1998, 1669.
(93) Burland, M. C.; Pontz, T. W.; Meyer, T. Y. Organometallics 2002,
21, 1933.
(94) Cantrell, G. K.; Meyer, T. Y. Chem. Commun. 1997, 1551.
(95) Cantrell, G. K.; Meyer, T. Y. Organometallics 1997, 16, 5381.
(96) Cantrell, G. K.; Meyer, T. Y. J. Am. Chem. Soc. 1998, 120, 8035.

Cyclopentadienyl-Amidinate Titanium Imido Compounds
Organometallics, Vol. 25, No. 5, 2006 1179
Without doubt these reactions are in principle able to proceed
via a [2+2] cycloaddition/extrusion process (Chauvin-type98
mechanism, cf. olefin metathesis), as clearly demonstrated by
Bergman for zirconocene imido systems.90,91,97 However, in
other instances (so far specifically where ancillary chloride
ligands are present) it appears that an acid-mediated (non-
Chauvin-type) mechanism could also be operative.92,93 Since
certain of our cyclopentadienyl-amidinate titanium imido sys-
tems undergo cycloaddition and subsequent metathesis (extru-
sion) reactions with aldehydes and ketones, we hoped that they
could be used to gain further experimental data on the imide/
imine metathesis reaction.
(beyond the range of this present work) would be required to
confirm this and determine the scope of the reaction and any
potential catalytic application. The slower rate of reaction of
PhC(NTol)H in comparison with that of PhCOH is attributed
to the increased steric bulk of the imine and the reduced
electrophilicity of the imine CdN carbon.
Scheme 7. Reaction of Ti(η-C5Me5)(NtBu){PhC(NiPr2)2} (6)
t
with Primary Amides RCONH2 (R ) Ph, Me(CH2)4, or Bu
Previous studies showed that the aldimine PhC(NTol)H would
be a suitable substrate (aryl aldimines are more reactive than
alkyl aldimines or ketimines). For comparison with the chemistry
so far described, reactions between PhC(NTol)H and the imido
compounds 6, 9, and 10 were screened by NMR tube scale
experiments in C6D6. No reaction was observed (even for 10)
either at room temperature or at 80 °C, in contrast to the
analogous reactions with PhCOH (vide supra). However,
although a cycloaddition product between 10 and the imine was
not observed, it is nonetheless possible that a degenerate
metathesis reaction (i.e., exchange of TidNTol and CdNTol)
could be occurring via a short-lived intermediate and therefore
not detected by NMR spectroscopy.
Reactions with Organic Amides RCONH2. Bergman has
recently reported that Cp2ZrMe2 reacts with certain organic
primary amides RCONH2 to form [Cp2Zr(O)]x and the corre-
sponding nitriles RCN (presumably via transient imido species
of the type Cp2Zr{NC(O)R}).100 Apart from this zirconocene
system, the only other example of an early transition metal-
mediated dehydration reaction of primary amides was with TiCl4
and base at 0 °C.101 With these observations in mind, we were
interested to examine the reactions of Ti(η-C5Me5)(NtBu){MeC-
(NiPr)2} (6) and related compounds with selected primary
amides to see if this offered a method for their conversion to
nitriles.102
To further probe this possibility, we used the p-dimethyl-
aminophenyl analogue of 10, namely, Ti(η-C5Me5)(N-4-C6H4-
NMe2)(MeC(NiPr)2} (37), prepared from 6 and p-dimethyl-
aniline.46,47 No reaction between 34 and PhC(NTol)H occurred
at room temperature in C6D6, but on heating to 80 °C for 19 h,
60% conversion of 37 to 10 was observed (eq 5), together with
resonances attributed to the expected organic product of
metathesis, namely, PhC(N-4-C6H4NMe2)H (confirmed by a
parent ion in the APCI mass spectrum).99
Ti(η-C5Me5)(NtBu){MeC(NiPr)2} (6) was treated with 1.0
equiv of benzamide, hexanoamide, or trimethylacetamide on
the NMR tube scale in the presence of a 1,4-dimethoxybenzene
internal standard. The 1H NMR spectra were monitored over 1
h and showed consumption of the amide with concomitant
formation of the corresponding nitrile, as verified by comparison
with authentic samples. The reactions yielded the oxo dimer
223 as the dominant organometallic product. The reactions with
benzamide and hexanoamide showed complete conversion
within 1 h, while reaction with the sterically encumbered
trimethylacetamide had achieved only 60% conversion to
trimethylacetonitrile after 2 days. A likely intermediate based
on Bergman’s work100 is species VI (Scheme 7).
The imide/imine exchange of 37 with PhC(NTol)H is a rare
example of this type of metathesis reaction. Although no
intermediate was observed, it is likely that a species of the type
V is involved in this reaction. Detailed mechanistic studies
Corresponding reactions were also carried out to evaluate
other titanium imido and amido compounds as reagents for these
(100) Ruck, R. T.; Bergman, R. G. Angew. Chem., Int. Ed. 2004, 43,
5375.
(101) Lehnert, W. Tetrahedron Lett. 1971, 1501.
(102) For leading references on the conversion of primary amides to
nitriles see ref 100 and references therein.
(97) Krska, S. W.; Zuckerman, R. L.; Bergman, R. G. J. Am. Chem.
Soc. 1998, 120, 11828.
(98) Herisson, J.-L.; Chauvin, Y. Macromol. Chem. 1970, 141, 161.
(99) Tabei, N.; Saiton, E. Bull. Chem. Soc. Jpn. 1969, 42, 1440.

1180 Organometallics, Vol. 25, No. 5, 2006
Guiducci et al.
transformations. Ti(NtBu)Cl2(py)3,33 Ti(NMe2)2Cl2,103,104 Ti(η-
C5Me5)(NtBu)Cl(py),32 and Ti(NtBu){Me3SiNC(Ph)N(CH2)3-
(Ph)N(CH2)3NMe2}Cl were prepared according to previously
described methods.33,46,47,103-105,108 All other compounds and re-
agents were purchased and were either used without further
purification or purified by standard methods.109
Ti(η-C5Me5)(NtBu){PhC(NSiMe3)2} (5). To a solution of 714
mg (1.94 mmol) of [Ti(η-C5Me5)(NtBu)Cl(py)] in ca. 30 mL of
benzene was added 532 mg (1.97 mmol) of Li[PhC(NSiMe3)2]
dissolved in ca. 40 mL of benzene. After 16 h, the volatiles were
removed under reduced pressure and the residues were purified by
tube distillation (160 °C, 3 × 10-6 Torr, 2 h) to give 5 as a dark
red, waxy solid. Yield: 410 mg (41%). The compound was
characterized by comparison of spectroscopic data with literature
values.30
Ti(η-C5Me5)(NtBu){MeC(NiPr)2} (6). To a solution of 9.48 g
(0.026 mol) of Ti(η-C5Me5)(NtBu)Cl(py) in ca. 200 mL of benzene
was added 3.81 g (0.026 mol) of Li[MeC(NiPr)2] slurried in ca. 30
mL of benzene over a period of 30 min. After 16 h the solution
was filtered, and volatiles were removed under reduced pressure
to give 6 as a waxy brown solid. Yield: 10.25 g (99%). 1H NMR
(C6D6, 500.0 MHz, 298 K) δ: 3.56 (2 H, apparent sept, J ) 6.4
Hz, NCHMeMe), 2.13 (15 H, s, C5Me5), 1.68 (3 H, s, MeCN2),
1.10 (9 H, s, NtBu), 1.04 (6 H, d, J ) 6.4 Hz, NCHMeMe), 1.01
(6 H, d, J ) 6.4 Hz, NCHMeMe). 13C{1H} NMR (C6D6, 125.7
MHz, 298 K) δ: 163.6 (CN2), 118.9 (C5Me5), 66.0 (NCMe3), 47.9
(NCHMeMe), 31.8 (NCMe3), 25.2 (NCHMeMe), 24.0 (NCH-
MeMe), 11.2 (C5Me5), 9.8 (MeCN2). IR (NaCl plates, Nujol mull,
cm-1): 2722 (w), 2041 (w), 1597 (w), 1339 (s, br), 1317 (m), 1244
(s), 1213 (s), 1174 (s), 1143 (w), 1122 (m), 1057 (w), 1018 (m),
812 (m), 754 (w), 723 (m), 700 (w), 623 (m), 591 (m), 554 (s),
534 (s), 507 (w), 419 (s). Anal. Found (calc for C22H41N3Ti): C
67.1 (66.8); H 10.4 (10.5); N 10.2 (10.6). EIMS: m/z 395 [M]+,
380 [M - Me]+.
1
NMe2}Cl105 all showed H NMR evidence for conversion of
the amide starting materials to nitrile compounds, although none
of these reagents facilitated complete conversion of the bulky
trimethylacetamide to trimethylacetonitrile.
Conclusions
Metathesis reactions of half-sandwich titanium imido com-
plexes combined with tert-butyl imide/arylamine exchange
strategies provide a useful route to a family of 16-valence-
electron cyclopentadienyl-amidinate derivatives. The tert-butyl
and aryl imido complexes show significant differences in
reactivity, the former reacting more slowly and being, in general,
more prone to cycloaddition/elimination reactions. The aryl
imido complexes can undergo single-, double-, and cross-
coupling reactions with isocyanates and CO2. In addition to their
reactions with isocyanates, the cyclopentadienyl-amidinate
complexes undergo rapid cycloaddition-elimination reactions
with CS2, COS, PhNO, ketones, aldehydes, and imines, although
in some instances intermediates could be observed or isolated.
Interestingly, the aryl imido cycloaddition products appear to
show increasing stability with increasing steric crowding. Similar
trends have been noted before in the reactions of CO2 with
certain cyclopentadienyl-amidinate tert-butyl imido complexes.28
Experimental Section
General Methods and Instrumentation. All manipulations were
carried out using standard Schlenk line or drybox techniques under
an atmosphere of argon or of dinitrogen. Solvents were predried
over 4 Å molecular sieves and were refluxed over appropriate drying
agents under a dinitrogen atmosphere and collected by distillation.
Deuterated solvents were dried over appropriate drying agents,
distilled under reduced pressure, and stored under dinitrogen in
Teflon valve ampules. NMR samples were prepared under dini-
trogen in 5 mm Wilmad 507-PP tubes fitted with J. Young Teflon
valves. 1H, 13C{1H}, and 13C NMR spectra were recorded on Varian
Ti(η-C5H4Me)(NtBu){PhC(NSiMe3)2} (7). To a solution of 6.79
g (0.022 mol) of Ti(η-C5H4Me)(NtBu)Cl(py) in ca. 70 mL of
benzene was added 5.88 g (0.022 mol) of Li[PhC(NSiMe3)2]
dissolved in ca. 200 mL of benzene. After 16 h the solution was
filtered, and the volatiles were then removed under reduced pressure
to give 7 as a waxy red-brown solid. Yield: 9.34 g (93%). 1H NMR
(C6D6, 500.0 MHz, 298 K) δ: 7.16 (3 H, m, o-, p-C6H5), 7.03 (2
H, m, m-C6H5), 6.87 (2 H, virtual t, C5H2(â)H2(R)Me), 5.80 (2 H,
virtual t, C5H2(â)H2(R)Me), 2.06 (3 H, s, C5H4Me), 1.17 (9 H, s,
NtBu), -0.10 (18 H, s, SiMe3). 13C{1H} NMR (C6D6, 125.7 MHz,
298 K) δ: 170.6 (CN2), 139.7 (i-C6H5), 128.6 (o-C6H5), 128.1 (m-
C6H5), 127.5 (p-C6H5), 123.0 (C2(â)C2(R)CMe), 113.1 (C2(â)C2-
(R)CMe), 108.8 (C2(â)C2(R)CMe), 67.0 (NCMe3), 32.7 (NCMe3),
14.8 (C2(â)C2(R)CMe), 2.0 (SiMe3). IR (KBr plates, Nujol mull,
cm-1): 3061 (w), 2728 (w), 2363 (w), 1946 (w), 1614 (w, br),
1578 (w, br), 1350 (s), 1305 (m), 1248 (s), 1209 (m), 1177 (m),
1123 (m), 1073 (m), 1047 (w), 1033 (m), 1007 (s), 996 (s), 935
(w), 918 (m), 839 (s, br), 805 (w), 785 (s), 764 (s), 723 (w), 701
(m), 687 (w), 625 (m, br), 604 (m, br), 548 (s), 507 (s), 446 (m),
402 (m). Anal. Found (calc for C23H39N3Si2Ti): C 59.8 (59.8); H
8.2 (8.5); N 9.0 (9.1). EIMS: m/z 461 [M]+, 446 [M - Me]+.
Ti(η-C5H4Me)(NtBu){MeC(NiPr)2} (8). A 2.50 g (7.96 mmol)
sample of Ti(η-C5H4Me)(NtBu)Cl(py) in ca. 140 mL of benzene
was added to 1.18 g (7.96 mmol) of Li[MeC(NiPr)2] slurried in ca.
30 mL of benzene. After 16 h, the volatiles were removed under
reduced pressure, and the residue was extracted with ca. 100 mL
of pentane and filtered. Volatiles were then again removed under
reduced pressure to afford 8 as a red oil. Yield: 2.59 g (96%). 1H
NMR (C6D6, 500.0 MHz, 298 K) δ: 6.68 (2 H, virtual t, C5H2-
(â)H2(R)Me), 5.94 (2 H, virtual t, C5H2(â)H2(R)Me), 3.55 (2 H,
apparent sept., J ) 6.4 Hz, NCHMeMe), 1.98 (3 H, s, C5H2(â)-
1
Unity Plus 500 and Varian Mercury spectrometers. H and 13C
assignments were confirmed where necessary with the use of NOE,
DEPT-135, DEPT90, DEPT-45, and two-dimensional 1H-1H and
13C-1H NMR experiments. All spectra were referenced internally
to residual protio-solvent (1H) or solvent (13C) resonances and are
reported relative to tetramethylsilane (δ ) 0 ppm). Chemical shifts
are quoted in δ (ppm) and coupling constants in hertz. Infrared
spectra were prepared as Nujol mulls or thin films between KBr
plates and were recorded on Perkin-Elmer 1600 and 1700 series
spectrometers. Infrared data are quoted in wavenumbers (cm-1).
Mass spectra were recorded by the mass spectrometry service of
the University of Oxford’s Inorganic Chemistry Laboratory.
Combustion analyses were recorded by the analytical services of
the University of Oxford’s Inorganic Chemistry Laboratory.
Starting Materials and Literature Preparations. The com-
pounds Li[MeC(NiPr)2],106 Li[PhC(NSiMe3)2],107 Ti(NtBu)Cl2(py)3,
Ti(NMe2)2Cl2, Ti(η-C5Me5)(NtBu)Cl(py), Ti(η-C5H4Me)(NtBu)Cl-
(py), Ti(η-C5Me5){N(Tol)C(O)O}{MeC(NiPr)2} (29), Ti(η-C5-
Me5)(N-4-C6H4NMe2)(MeC(NiPr)2} (34), and Ti(NtBu){Me3SiNC-
(103) Bradley, D. C.; Thomas, I. M. J. Chem. Soc. 1960, 3857.
(104) Diamond, G. M.; Jordan, R. F.; Petersen, J. L. Organometallics
1996, 15, 4030.
(105) Boyd, C. L.; Guiducci, A. E.; Dubberley, S. R.; Tyrrell, B. R.;
Mountford, P. J. Chem. Soc., Dalton Trans. 2002, 4175.
(106) Coles, M. P.; Swenson, D. C.; Jordan, R. F. Organometallics 1997,
16, 5183.
(108) Dunn, S. C.; Batsanov, A. S.; Mountford, P. Chem. Commun. 1994,
2007.
(107) Boere, R. T.; Oakley, R. T.; Reed, R. W. J. Organomet. Chem.
1987, 331, 161.
(109) Armarego, W. L. F.; Chai, C. L. L. Purification of Laboratory
Chemicals, 5th ed.; 2003.

Cyclopentadienyl-Amidinate Titanium Imido Compounds
Organometallics, Vol. 25, No. 5, 2006 1181
H2(R)Me), 1.54 (3 H, s, MeCN2), 1.11 (9 H, s, NtBu), 1.06 (6 H,
d, J ) 6.4 Hz, NCHMeMe), 0.87 (6 H, d, J ) 6.4 Hz, NCHMeMe).
13C{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 159.3 (MeCN2), 121.8
(C2(â)C2(R)CMe), 112.6 (C2(â)C2(R)CMe), 108.5 (C2(â)C2(R)-
CMe), 66.8 (NCMe3), 48.2 (NCHMeMe), 32.9 (NCMe3), 25.9
(NCHMeMe), 25.7 (NCHMeMe), 14.2 (C2(â)C2(R)CMe), 10.3
(MeCN2). IR (KBr plates, neat thin film, cm-1): 2963 (s), 2931
(s), 2867 (m), 2601 (w), 2362 (w), 1489 (s, br), 1451 (s, br), 1378
(m), 1361 (m), 1336 (s), 1317 (m), 1247 (s), 1225 (s), 1210 (m),
1174 (m), 1145 (w), 1123 (m), 1091 (m), 1059 (w), 1033 (w), 986
(w), 935 (w), 842 (m), 785 (s, br), 721 (m), 621 (w), 590 (m, br),
558 (m), 534 (w), 507 (w), 470 (w). EIMS: m/z 339 [M]+, 324 [M
- Me]+, 268 [M - NtBu]+.
(w), 761 (m), 722 (m, br), 681 (w, br), 627 (w), 609 (w), 598 (w),
500 (m), 413 (m) cm-1. Anal. Found (calc for C46H76N4S2Si4Ti2):
C 57.7 (57.7); H 7.5 (8.0); N 5.7 (5.9). EIMS: m/z ) 821, [M -
C5Me5]+, m/z ) 789 [M - C5Me5 - S]+.
[Ti(η-C5Me5)(µ-S){MeC(NiPr)2}]2 (12). A 305 mg (0.69 mmol)
sample of Ti(η-C5Me5)(NtBu)(MeC(NiPr)2} (6) was dissolved in
ca. 15 mL of benzene. The vessel was freeze-pump-thawed three
times and back-filled with COS at a pressure of 500 mmHg, and
the mixture was stirred for 18 h. Volatiles were removed under
reduced pressure, and the residues extracted with ca. 10 mL of
benzene. This was layered with ca. 15 mL of pentane to afford 12
as red-brown crystals. Yield: 55 mg (22%). 1H NMR (C6D6, 500.0
MHz, 298 K) δ: 3.59 (4 H, apparent sept, J ) 6.6 Hz, NCHMeMe),
2.28 (30 H, s, C5Me5), 1.81 (6 H, s, MeCN2), 1.32 (12 H, d, J )
6.6 Hz, NCHMeMe), 1.26 (12 H, d, J ) 6.6 Hz, NCHMeMe). 13C-
{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 167.2 (MeCN2), 125.7
(C5Me5), 49.6 (NCHMeMe), 25.7 (NCHMeMe), 24.8 (NCHMeMe),
15.5 (MeCN2), 14.8 (C5Me5). IR (KBr plates, Nujol mull): 2721
(w), 1645 (w), 1558 (w), 1329 (s), 1296 (m), 1262 (m), 1206 (s),
1190 (s), 1169 (m), 1143 (m), 1114 (m), 1019 (m), 808 (m), 795
(m), 768 (w), 723 (w), 675 (w), 629 (w), 571 (w), 548 (w), 414 (s)
cm-1. Anal. Found (calc for C36H64N4S2Ti2): C 60.7 (60.7); H 9.1
(9.1); N 7.5 (7.9). EIMS: m/z ) 712 [M]+, m/z ) 356 [1/2M]+.
[Ti(η-C5H4Me)(µ-S){PhC(NSiMe3)2}]2 (13). A 103 mg (0.22
mmol) sample of Ti(η-C5H4Me)(NtBu){PhC(NSiMe3)2} (7) was
dissolved in ca. 10 mL of benzene, and to this was added an excess
(0.40 mL, 6.65 mmol) of CS2. Volatiles were removed under
reduced pressure after 5 days. The residues were extracted into a
minimum amount of pentane and cooled to -30 °C to afford 13 as
a brown powder. Yield: 15 mg (16%). 1H NMR (C6D6, 500.0 MHz,
298 K) δ: 7.59 (2 H, d, J ) 6.8 Hz, o-C6H5), 7.05 (6 H, m, m-,
p-C6H5), 6.86 (2 H, d, J ) 6.8 Hz, o-C6H5), 6.80 (4 H, virtual
triplet, J ) 2.7 Hz, C5H2(â)H2(R)Me), 6.35 (4 H, virtual triplet, J
) 2.7 Hz C5H2(â)H2(R)Me), 2.70 (6 H, s, C5H2(â)H2(R)Me), 0.01
(18 H, s, SiMe3. 13C{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 175.2
(C6H5CN2), 139.9 (i-C6H5CN2), 128.7 (o-C6H5CN2), 128.6 (m-C6H5-
CN2), 128.3 (p-C6H5CN2), 126.5 (C2(â)C2(R)CMe), 116.1 (C2(â)-
C2(R)CMe), 114.9 (C2(â)C2(R)CMe), 18.3 (C2(â)C2(R)CMe), 3.06
(SiMe3). IR (KBr plates, Nujol mull): 2726 (w), 2044 (w), 1600
(w), 1499 (m), 1244(s), 1170 (m), 1071 (w), 1055 (w), 1041 (w),
1031 (w), 1002 (m), 983 (s), 917 (m), 838 (s, br), 803 (s), 783
(m), 760 (s), 737 (m), 721 (s), 679 (w), 607 (w, br), 504 (s), 417
(s) cm-1. Anal. Found (calc for C38H60N4S2Si4Ti2): C 57.3 (57.3),
H 7.5 (7.6), N 7.0 (7.0). EIMS: m/z ) 844 [M]+, m/z ) 422
[1/2 M]+.
Ti(η-C5Me5)(NAr){MeC(NiPr)2} (9). ArNH2 (1.4 mL, 1.37 g,
0.011 mol) was added to a solution of 4.53 g (0.011 mol) of Ti-
(η-C5Me5)(NtBu){MeC(NiPr)2] (6) in ca. 100 mL of pentane to give
a green solution. After 16 h the volatiles were removed under
reduced pressure. The residue was extracted with ca. 50 mL of
dichloromethane and filtered, and the volatiles were removed under
reduced pressure to leave an oily green solid. Trituration with
1
pentane afforded 9 as a green powder. Yield: 4.62 g (95%). H
NMR (C6D6, 500.0 MHz, 298 K) δ: 7.02 (2 H, d, J ) 7.3 Hz,
m-aryl), 6.73 (1 H, t, J ) 7.3 Hz, p-aryl), 3.56 (2 H, apparent sept.,
J ) 6.4 Hz, NCHMeMe), 2.30 (6 H, s, N-2,6-C6H3Me2), 1.98 (15
H, s, C5Me5), 1.67 (3 H, s, MeCN2), 1.07 (6 H, d, J ) 6.4 Hz,
NCHMeMe), 1.00 (6 H, d, J ) 6.4 Hz, NCHMeMe). 13C{1H} NMR
(C6D6, 125.7 MHz, 298 K) δ: 164.1 (CN2), 158.5 (i-aryl), 131.5
(o-aryl), 127.6 (m-aryl), 120.7 (p-aryl), 118.9 (C5Me5), 49.1
(NCHMeMe), 25.9 (NCHMeMe), 25.1 (NCHMeMe), 20.7 (C6H3-
Me2), 12.5 (MeCN2), 12.3 (C5Me5). IR (KBr disks, Nujol mull,
cm-1): 2720 (w), 2595 (w), 2046(w), 1892 (w), 1838 (w), 1785
(w), 1653 (w), 1623 (w), 1587 (m), 1407 (s), 1364 (s), 1334 (s),
1310(s), 1295 (s), 1216 (s), 1174 (m), 1157 (w), 1139 (w), 1121
(m), 1096 (m), 1055 (w), 1014 (m, br), 973 (m), 959 (m), 914 (w),
894 (w), 873 (w), 815 (s), 760 (s), 743 (m), 723 (m), 618 (m), 589
(m), 574 (w), 565 (m), 547 (w), 445 (s). Anal. Found (calc for
C26H41N3Ti): C 70.0 (70.4); H 9.3 (9.3); N 9.4 (9.5). EIMS: m/z
443 [M]+.
Ti(η-C5Me5)(NTol){MeC(NiPr)2} (10). A 676 mg (1.72 mmol)
sample of Ti(η-C5Me5)(NtBu){MeC(NiPr)2} (6) and 186 mg (1.73
mmol) of TolNH2 were dissolved in ca. 40 mL of benzene. After
16 h the volatiles were removed under reduced pressure, and the
product was isolated as a green solid, which was further purified
by tube distillation (170 °C, 2 × 10-5 Torr, 4 h) to give 10 as a
1
green solid. Yield: 170 mg (50%). H NMR (C6D6, 500.0 MHz,
[Ti(η-C5H4Me)(µ-S){MeC(NiPr)2}]2 (14). Ti(η-C5H4Me)-
(NtBu){MeC(NiPr)2} (8) (85 mg, 0.25 mmol) was dissolved in ca.
10 mL of pentane, and to this was added an excess (0.40 mL, 6.65
mmol) of CS2. After 3 days, the supernatant was filtered away from
brown crystalline needles that had formed (25 mg, 33% yield). 1H
NMR (C6D6, 500.0 MHz, 298 K): 6.57 (4 H, virtual t, C5H2(â)-
H2(R)Me), 6.39 (4 H, virtual t, C5H2(â)H2(R)Me), 3.45 (4 H,
apparent sept, J ) 6.6 Hz, NCHMeMe), 2.59 (6 H, s, C5H2(â)H2-
(R)Me), 1.55 (6 H, s, MeCN2), 1.38 (12 H, d, J ) 6.6 Hz,
NCHMeMe), 1.12 (12 H, d, J ) 6.6 Hz, NCHMeMe). 13C{1H}
NMR (C6D6, 125.7 MHz, 298 K) δ: 166.3 (MeCN2), 127.4 (C2-
(â)C2(R)CMe), 115.1 (C2(â)C2(R)CMe), 114.3 (C2(â)C2(R)CMe),
49.7 (NCHMeMe), 24.9 (NCHMeMe), 23.6 (NCHMeMe), 18.2 (C2-
(â)C2(R)CMe), 9.99 (MeCN2). IR (KBr plates, Nujol mull): 1340
(m), 1313 (w), 1261 (m), 1210 (w), 1173 (w), 1069 (w), 1038 (w),
935 (w), 859 (w), 804 (m), 723 (w), 684 (w) cm-1. EIMS: m/z )
600 [M]+. A satisfactory elemental analysis could not be obtained.
298 K) δ: 6.93 (2 H, d, J ) 7.9 Hz, m-(N-4-C6H4Me)), 6.74 (2 H,
d, J ) 7.9 Hz, o-(N-4-C6H4Me)), 3.54 (2 H, apparent sept., J )
6.3 Hz, NCHMeMe), 2.13 (3 H, s, N-4-C6H4Me), 2.07 (15 H, s,
C5Me5), 1.51 (3 H, s, MeCN2), 1.10 (6 H, d, J ) 6.3 Hz,
NCHMeMe), 0.97 (6 H, d, J ) 6.3 Hz, NCHMeMe). 13C{1H} NMR
(C6D6, 125.7 MHz, 298 K) δ: 163.6 (CN2), 158.9 (i-N-4-C6H4-
Me), 129.0 (m-N-4-C6H4Me), 127.9 (p-N-4-C6H4Me), 123.2 (o-N-
4-C6H4Me), 120.6 (C5Me5), 49.3 (NCHMeMe), 26.2 (NCHMeMe),
25.3 (NCHMeMe), 21.1 (N-4-C6H4Me), 12.3 (C5Me5), 11.6 (MeCN2).
IR (KBr plates, Nujol mull, cm-1): 2958 (s), 1871 (w), 1655 (w),
1599 (m), 1490 (s), 1315 (s, br), 1261 (s), 1212 (s, br), 1171 (m),
1141 (w), 1120 (w), 1099 (w, br), 1019 (s), 964 (m), 817 (s, br),
723 (w), 656 (m), 625 (w), 607 (w), 557 (w), 526 (w), 589 (m),
440 (m, br). Anal. Found (calc for C25H39N3Ti): C 69.9 (69.9) H
9.2 (9.2) N 9.3 (9.8). EIMS: m/z 429 [M]+.
[Ti(η-C5Me5)(µ-S){PhC(NSiMe3)2}]2 (11). A 115 mg (0.22
mmol) sample of Ti(η-C5Me5)(NtBu){PhC(NSiMe3)2} (5) was
dissolved in ca. 15 mL of benzene, and to this was added an excess
(0.40 mL, 6.65 mmol) of CS2. After 10 days compound 11 was
isolated as red crystals. Yield: 71 mg (68%). IR (KBr plates, Nujol
mull): 2726 (w), 1456 (s, br), 1259 (m), 1244 (s), 1160 (w), 1095
(m, br), 1020 (m, br), 1002 (w), 983 (s), 920 (w), 835 (s, br), 781
[Ti(η-C5Me5)(µ-S){N(iPr)C(Me)N(iPr)C(S)S}]2 (18). A 127 mg
(0.32 mmol) sample of Ti(η-C5Me5)(NtBu){MeC(NiPr)2} (6) was
dissolved in ca. 10 mL of benzene, and an excess (0.40 mL, 6.65
mmol) of CS2 was added. After 10 days, volatiles were removed
under reduced pressure and the residue was extracted into ca. 40

1182 Organometallics, Vol. 25, No. 5, 2006
Guiducci et al.
mL of pentane. Evaporation of the volatiles afforded 18 as an olive-
brown powder. Yield: 110 mg (80%). 1H NMR (C6D6, 500.0 MHz,
298 K) δ: 5.19 (4 H, apparent sept, J ) 6.8 Hz, CNCHMe2), 3.38
(4 H, apparent sept, J ) 6.6 Hz, TiNCHMe2), 2.39 (30 H, s, C5Me5),
1.98 (6 H, s, MeCN2, 1.25, 6 H, d, CNCHMeMe), 1.17 (6 H, d,
CNCHMeMe), 1.06 (12 H, d, J ) 6.6 Hz, TiNCHMeMe). 13C{1H}
NMR (C6D6, 125 MHz, 298K) δ: 202.3 (C(S)S), 154.1 (MeCN2),
127.0 (C5Me5), 53.4 (CNCHMeMe), 51.7 (TiNCHMeMe), 23.2
(TiNCHMeMe), 20.7 (CNCHMeMe), 20.1 (MeCN2), 14.6 (C5Me5).
IR (KBr plates, Nujol mull): 2955 (s), 2726 (w), 1398 (m), 1357
(s), 1343 (w), 1315 (w), 1261 (w), 1227 (m, br), 1169 (w), 1147
(m), 1123 (w), 1110 (w, br), 1063 (w), 1020 (w), 962 (w), 864
(w), 804 (w, br), 723 (m, br), 667 (w), 605 (w), 521 (w), 496 (w),
433 (m, br), 404 (m) cm-1. Anal. Found (calc for C38H64N4S6Ti2):
C 52.6 (52.8); H 9.3 (7.5); N 6.0 (6.5) S 23.5 (22.2). EIMS: m/z
) 864 [M]+.
NMR Tube Scale Reactions of 5, 6, 7, and 8 with COS. The
general procedure was as follows. About 0.02 mmol of the imido
compound was dissolved in 0.6 mL of C6D6. The solution was
freeze-pump-thawed three times and then back-filled with COS
at a pressure of 500 mmHg. The reaction was monitored using 1H
NMR spectroscopy, and the products were identified by comparison
with authentic samples. The reaction of 6 with COS to form 12
was also performed on a preparative scale.
NCHbMeMe. 13C{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 195.8
(SCO), 169.4 (MeCN2), 146.7 (i-2,6-C6H3Me2), 133.6 (o-2,6-C6H3-
Me2), 133.3 (o-2,6-C6H3Me2), 130.6 (m-2,6-C6H3Me2), 128.5 (m-
2,6-C6H3Me2), 125.7 (C5Me5), 51.8 (NCHaMeMe), 49.9 (NCHb-
MeMe), 26.5 (NCHbMeMe), 25.2 (NCHaMeMe), 24.5 (NCHaMeMe),
24.1 (NCHbMeMe), 20.0 (2,6-C6H3MeMe), 19.6 (2,6-C6H3MeMe),
14.1 (MeCN2), 13.5 (C5Me5). IR (KBr plates, Nujol mull): 2724
(w), 2363 (w), 2274 (w), 1832 (w), 1718 (w), 1672 (m), 1648 (w),
1616 (s), 1581 (m, br), 1494 (m), 1403 (m), 1319 (s, br), 1253
(m), 1232 (s), 1205 (s), 1114 (w), 1094 (w), 1061 (w), 1011 (m,
br), 956 (w), 938 (s), 883 (w), 819 (m), 790 (m), 763 (m), 724
(m), 698 (w), 676 (w), 631 (w), 581 (m), 550 (w), 491 (w), 447
(m), 417 (m), 402 (m) cm-1. Anal. Found (calc for C27H41N3-
OSTi): C 64.5 (64.4); H 8.3 (8.2); N 8.1 (8.3); S 7.6 (6.4).
NMR Tube Scale Reaction of Ti(η-C5Me5)(NTol){MeC-
(NiPr)2} (10) with COS. A 22.5 mg (0.05 mmol) sample of Ti-
(η-C5Me5)(NTol){MeC(NiPr)2} was dissolved in 0.6 mL of C6D6.
The solution was freeze-pump-thawed (× 3), and the headspace
filled with COS at a pressure of 500 mmHg. The reaction was
1
monitored using H NMR spectroscopy.
NMR Tube Scale Reaction of Ti(η-C5Me5)(NTol){MeC-
(NiPr)2} (10) with CS2. A 22.5 mg (0.05 mmol) sample of Ti(η-
C5Me5)(NTol){MeC(NiPr)2} was dissolved in 0.6 mL of C6D6. To
this was added a few drops (excess) CS2. A color change from
green to brown occurred within 5 min. The reaction was monitored
Ti(η-C5Me5){N(Ar)C(S)S}{MeC(NiPr)2} (19). A 244 mg (0.55
mmol) sample of Ti(η-C5Me5)(NAr){MeC(NiPr)2} (9) was dis-
solved in ca. 20 mL of pentane to give a dark green solution, and
to this was added an excess (0.40 mL, 6.65 mmol) of CS2. After 6
h the volatiles were removed under reduced pressure to afford the
1
by H NMR spectroscopy.
NMR Tube Scale Reaction of Ti(η-C5Me5)(NtBu){MeC-
(NiPr)2} (6) with tert-Butyl Isocyanate. A 9.9 mg (0.03 mmol)
sample of Ti(η-C5Me5)(NtBu){MeC(NiPr)2} (6) was dissolved in
0.6 mL of C6D6, and to this was added 3.0 µL (3 mg, 0.03 mmol)
of tert-butyl isocyanate via microliter syringe. The reaction was
monitored by 1H NMR spectroscopy. Complete conversion to trans-
[Ti(η-C5Me5)(µ-O){MeC(NiPr)2}]2 and 1,3-di-tert-butyl carbodi-
imide was observed after 25 days. A corresponding procedure was
used to examine the reactivity of 5, 7, and 8 with tert-butyl
isocyanate.
1
product as a very fine black powder. Yield: 170 mg (60%). H
NMR (C6D6, 500.0 MHz, 298 K) δ: 7.02-7.00 (3 H, m, m-, p-2,6-
C6H3Me2), 3.08 (1 H, apparent sept, J ) 6.6 Hz, NCHaMeMe),
3.07 (1 H, apparent sept, J ) 6.6 Hz, NCHbMeMe), 2.23 (3 H, s,
2,6-C6H3MeMe), 2.12 (3 H, s, 2,6-C6H3MeMe), 1.85 (15 H, s,
C5Me5), 1.45 (3 H, s, MeCN2), 0.98 (3 H, d, J ) 6.6 Hz,
NCHaMeMe), 0.91 (3 H, d, J ) 6.6 Hz, NCHaMeMe), 0.72 (3 H,
d, J ) 6.6 Hz, NCHbMeMe), 0.34 (3 H, d, J ) 6.6 Hz, NCHb-
MeMe). 13C{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 201.8 (SCS),
169.2 (MeCN2), 148.2 (i- 2,6-C6H3Me2), 135.1 (o- 2,6-C6H3Me2),
134.1 (o-2,6-C6H3Me2), 133.3 (m-2,6-C6H3Me2), 130.3 (C5Me5),
125.7 (m-2,6-C6H3Me2), 125.4 (p-2,6-C6H3Me2), 52.5 (NCHb-
MeMe), 49.7 (NCHaMeMe), 26.0 (NCHbMeMe), 24.5 (NCHa-
MeMe), 23.7 (NCHbMeMe), 23.1 (NCHaMeMe), 19.3 (2,6-
C6H3MeMe), 19.0 (2,6-C6H3MeMe), 14.8 (MeCN2), 13.6 (C5Me5).
IR (KBr plates, Nujol mull): 2721 (w), 2589 (w), 2364 (w), 1903
(w), 1762 (w), 1653 (w, br), 1623 (w), 1590 (w), 1563 (w, br),
1403 (s), 1344 (s), 1324 (s), 1296 (s), 1252 (s), 1198 (s), 1177 (s),
1125 (m), 1093 (s), 1055 (m), 1007 (s, br), 954 (w), 921 (w), 821
(s), 793 (s), 764 (s), 757 (s), 723 (m), 702 (m), 677 (m), 628 (w),
616 (w), 598 (w), 580 (w), 556 (m), 519 (m), 480 (w), 437 (s),
422 (s) cm-1. Anal. Found (calc for C27H41N3S2Ti): C 62.3 (62.4);
H 8.3 (8.0); N 8.0 (8.1).
Ti(η-C5Me5){N(Ar)C(NtBu)O}{MeC(NiPr)2} (21). A 163 mg
(0.37 mmol) sample of [Ti(η-C5Me5)(NAr){MeC(NiPr)2}] was
dissolved in ca. 10 mL of benzene to give a dark green solution.
To this was added 45 µL (39.1 mg, 0.39 mmol) of tert-butyl
isocyanate via microliter syringe. After 4 h, all volatiles were
removed under reduced pressure, and the residue was triturated with
ca. 5 mL of pentane to afford the product as a sticky brown solid.
Yield: 55 mg (27%). 1H NMR (C6D6, 500.0 MHz, 298 K) δ: 6.98
(1 H, d, J ) 7.3 Hz, m-2,6-C6H3Me2), 6.94 (1 H, d, J ) 7.3 Hz,
m-2,6-C6H3Me2), 6.88 (1 H, t, J ) 7.3 Hz, p-2,6-C6H3Me2), 3.32
(1 H, apparent sept, J ) 6.4 Hz, NCHaMeMe), 3.14 (1 H, apparent
sept, J ) 6.4 Hz, NCHbMeMe), 2.32 (3 H, s, 2,6-C6H3MeMe), 1.99
(3 H, s, 2,6-C6H3MeMe), 1.97 (15 H, s, C5Me5), 1.66 (9 H, s, tBu),
1.44 (3 H, s, MeCN2), 1.15 (3 H, d, J ) 6.4 Hz, NCHaMeMe),
0.99 (3 H, d, J ) 6.4 Hz, NCHbMeMe), 0.78 (3 H, d, J ) 6.4 Hz,
NCHbMeMe), 0.50 (3 H, d, J ) 6.4 Hz, NCHbMeMe). 13C{1H}
NMR (C6D6, 125.7 MHz, 298 K) δ: 166.9 (CN2), 152.5 (OCN),
148.8 (i-2,6-C6H3Me2), 133.6 (o-2,6-C6H3Me2), 133.0 (o-2,6-C6H3-
Me2), 127.4 (C5Me5), 127.6 (m-2,6-C6H3Me2), 124.1 (p-2,6-C6H3-
Me2), 51.9 (NCHaMeMe), 49.7 (NCHbMeMe), 32.9 (NCMe3), 25.5
(NCHbMeMe, NCHaMeMe (br)), 24.2 (NCHaMeMe, NCHbMeMe
(br)), 19.6 (2,6-C6H3Me2), 13.5 (MeCN2), 12.8 (C5Me5). NCMe3
resonance not observed. IR (KBr plates, Nujol mull, cm-1): 2957
(s), 2721 (w), 2602 (w), 2359 (w), 2140 (m), 1904 (w), 1652 (m),
1610 (m, br), 1549 (m), 1366 (m), 1349 (w), 1334 (m), 1313 (w),
1284 (m), 1262 (w), 1250 (w), 1232 (w), 1206 (s, br), 1174 (m,
br), 1138 (w), 1123 (w), 1097 (w), 1049 (m), 1017 (m), 955 (w),
940 (w), 919 (w), 860 (w), 792 (m), 764 (m), 732 (w), 634 (m,
br), 610 (w), 594 (w), 558 (w), 529 (w), 499 (m), 477 (m), 423
(w).
Ti(η-C5Me5){N(Ar)C(O)S}{MeC(NiPr)2} (20). In an ampule
equipped with a Young’s Teflon valve 277 mg (0.63 mmol) of
Ti(η-C5Me5)(NAr){MeC(NiPr)2} (9) was dissolved in ca. 20 mL
of benzene to give a dark green solution. The vessel was freeze-
pump-thawed three times and back-filled with COS at a pressure
of 500 mmHg. The solution was shaken for 5 min, after which
time a color change to dark red had occurred. Volatiles were
removed under reduced pressure to afford 20 as a black-brown solid.
1
Yield: 220 mg (70%). H NMR (C6D6, 500.0 MHz, 298 K) δ:
7.03 (1 H, m, p-2,6-C6H3Me2), 6.99 (2 H, m, m-2,6-C6H3Me2), 3.25
(1 H, apparent sept, NCHaMeMe), 2.97 (1 H, apparent sept, NCHb-
MeMe), 2.32 (3 H, s, 2,6-C6H3MeMe), 1.98 (3 H, s, 2,6-C6H3-
MeMe), 1.92 (15 H, s, C5Me5), 1.36 (3 H, s, MeCN2), 1.06 (3 H,
d, J ) 6.6 Hz, NCHaMeMe), 1.03 (3H, d, J ) 6.6 Hz, NCHaMeMe),
0.76 (3H, d, J ) 6.4 Hz, NCHbMeMe), 0.43 (3H, d, J ) 6.4 Hz),

Cyclopentadienyl-Amidinate Titanium Imido Compounds
Organometallics, Vol. 25, No. 5, 2006 1183
NMR Scale Reaction of Ti(η-C5Me5)(N-4-C6H4Me){MeC-
(NiPr)2} (10) with tert-Butyl Isocyanate. Ti(η-C5Me5)(N-4-C6H4-
Me){MeC(NiPr)2} (10) (13.2 mg, 0.03 mmol) was dissolved in 0.6
mL of C6D6, and to this was added 3.5 µL (3.0 mg, 0.03 mmol) of
tert-butyl isocyanate via microliter syringe. The reaction was
monitored using 1H NMR spectroscopy. A color change from green
to dark red was observed after ca. 10 min. Complete conversion of
the starting materials to trans-[Ti(η-C5Me5)(µ-O){MeC(NiPr)2}]2
and N-tert-butyl-N′-p-tolyl carbodiimide was observed after 16 h.
13.0 (C5Me5). IR (KBr plates, Nujol mull, cm-1): 2727 (w), 1655
(w), 1615 (w), 1595 (m), 1576 (s), 1504 (s), 1410 (m), 1338 (m),
1311 (m), 1295 (m), 1247 (m), 1208 (m), 1170 (w), 1118 (w), 1069
(w), 996 (w), 927 (w), 847 (w), 811 (w), 787 (w), 757 (w), 724
(w), 631 (w), 592 (w), 550 (w), 537 (w), 522 (w), 499 (w).
Ti(η-C5Me5){N(Tol)C(NAr)O}{MeC(NiPr)2} (24). A 234 mg
(0.55 mmol) sample of Ti(η-C5Me5)(NTol){MeC(NiPr)2} was
dissolved in ca. 20 mL of pentane. To this was added 76 µL (75
mg, 0.55 mmol) of 2,6-dimethylphenyl isocyanate. The solution
was stirred and then stood for 18 h at -30 °C. The supernatant
was then decanted off, and the residue was desolvated under reduced
pressure to afford a brown powder. Yield: 210 mg (67%). 1H NMR
(C6D6, 500.0 MHz, 298 K) δ: 7.57 (2 H, d, J ) 8.2 Hz, m-4-
C6H4Me), 7.23 (2 H, d, J ) 7.6 Hz, m-2,6-C6H3Me2), 7.09 (2 H, d,
J ) 8.2 Hz, o-4-C6H4Me), 6.99 (1 H, t, J ) 7.6 Hz, p-2,6-C6H3-
Me2), 3.61 (1 H, s (br), NCHaMeMe), 3.25 (1 H, s (br), NCHb-
MeMe), 2.51 (6 H, s, 2,6-C6H3Me2), 2.19 (3 H, s, 4-C6H4Me), 1.91
(15 H, s, C5Me5), 1.42 (3 H, s, MeCN2), 0.95 (6 H, s (br),
NCHa,bMeMe), 0.87 (3 H, s (br), NCHbMeMe), 0.61 (3 H, s (br),
NCHaMeMe). 13C{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 167.3
(CN2), 150.1 (OCN), 148.2 (i-NAr), 146.7 (i-NAr), 130.7 (o-4-
C6H4Me), 130.2 (o-4-C6H4Me), 128.7 (p-4-C6H4Me), 128.6 (m-
2,6-C6H3Me2), 127.6 (o-2,6-C6H3Me2), 123.4 (m-4-C6H4Me), 123.3
(m-4-C6H4Me), 121.0 (p-2,6-C6H3Me2), 49.8 (NCHbMeMe), 49.4
(NCHaMeMe), 24.6 (NCHbMeMe), 23.9 (NCHa,bMeMe), 23.6
(NCHaMeMe), 21.0 (4-C6H4Me), 19.8 (2,6-C6H3Me2), 15.4 (MeCN2),
12.6 (C5Me5). IR (KBr plates, Nujol mull, cm-1): 2957 (s), 2721
(w), 2670 (w), 1883 (w), 1732 (w), 1616 (s), 1582 (s), 1507 (s),
1350 (m), 1326 (s), 1257 (m), 1228 (m), 1214 (m), 1181 (w), 1169
(w), 1158 (w), 1144 (w), 1118 (w), 1106 (w), 1094 (w), 1076 (w),
1019 (w), 990 (m), 932 (w), 920 (m), 820 (m), 803 (m), 791 (w),
773 (w), 753 (m), 728 (m), 716 (m), 655 (w), 619 (w), 610 (w),
580 (w), 556 (w), 517 (w). Anal. Found (calc for C34H48N4OTi):
C 70.7 (70.8); H 8.9 (8.4); N 9.3 (9.7).
Ti(η-C5Me5){N(Tol)C(NTol)O}{MeC(NiPr)2} (25). A 437 mg
(1.02 mmol) sample of [Ti(η-C5Me5)(NTol){MeC(NiPr)2}] was
dissolved in ca. 25 mL of benzene, to which was added 131 µL
(138 mg, 1.02 mmol) of p-tolyl isocyanate. The resulting red
solution was stirred for 30 min, after which volatiles were removed
under reduced pressure. The residue was extracted with ca. 40 mL
of pentane and cooled to -30 °C. Brown crystals (235 mg, 41%
yield) were removed from the supernatant, which then had all
volatiles removed under reduced pressure to afford a further 66
mg of product as a brown powder. Total yield: 301 mg (53%). 1H
NMR (C6D6, 500.0 MHz, 298 K) δ: 7.81 (2 H, d, J ) 8.3 Hz,
o-Nb-4-C6H4Me), 7.41 (2 H, d, J ) 8.3 Hz, o-Na-4-C6H4Me), 7.22
(2 H, d, J ) 8.3 Hz, m-Nb-4-C6H4Me), 7.06 (2 H, d, J ) 8.3 Hz,
m-Na-4-C6H4Me), 3.61 (1 H, sept, J ) 6.8 Hz, NCHaMeMe), 3.26
(1 H, sept, J ) 6.6 Hz, NCHbMeMe), 2.21 (3 H, s, Nb-4-C6H4Me),
2.17 (3 H, s, Na-4-C6H4Me), 1.94 (15 H, s, C5Me5), 1.36 (3 H, s,
MeCN2), 1.05 (3 H, d, J ) 6.6 Hz, NCHbMeMe), 1.00 (3 H, d, J
) 6.6 Hz, NCHbMeMe), 0.92 (3 H, d, J ) 6.8 Hz, NCHaMeMe),
0.66 (3 H, d, J ) 6.8 Hz, NCHaMeMe). 13C{1H} NMR (C6D6, 125.7
MHz, 298 K) δ: 169.1 (CN2), 153.5 (OCN), 148.1 (i-N-4-C6H4-
Me), 146.5 (i-N-4-C6H4Me), 131.2 (p-N-4-C6H4Me), 129.5 (p-N-
4-C6H4Me), 129.2 (m-Nb-4-C6H4Me), 128.7 (m-Na-4-C6H4Me),
128.5 (C5Me5), 125.7 (o-Nb-4-C6H4Me), 123.7 (o-Na-4-C6H4Me),
50.3 (NCHbMeMe), 49.4 (NCHaMeMe), 24.3 (NCHaMeMe), 23.9
(NCHbMeMe), 21.1 (N-4-C6H4Me), 21.1 (N-4-C6H4Me), 14.6
(MeCN2), 12.6 (C5Me5). IR (KBr plates, Nujol mull, cm-1): 2727
(w), 2360 (w), 2342 (w), 1886 (w), 1609 (m), 1569 (s), 1500 (s),
1338 (s), 1322 (s), 1245 (m), 1208 (s), 1127 (m), 1107 (m), 1076
(w), 1018 (w), 996 (m), 918 (s), 817 (s), 785 (m), 724 (m), 698
(w), 681 (w), 642 (w), 620 (w), 611 (w), 578 (w), 544 (w), 515
(m), 487 (m), 440 (m), 408 (m). Anal. Found (calc for C33H46N4-
OTi): C 70.3 (70.5); H 8.4 (8.2); N 9.9 (10.0). MS (F.I.): m/z 562
[M]+.
Ti(η-C5Me5){N(Ar)C(NAr)O}{MeC(NiPr)2} (22). Ti(η-C5-
Me5)(NAr){MeC(NiPr)2} (273 mg, 0.62 mmol) was dissolved in
ca. 15 mL of benzene. To this was added 86 µL (84.6 mg, 0.62
mmol) of 2,6-dimethylphenyl isocyanate via microliter syringe, and
the solution was stirred for 21 h. Volatiles were then removed under
reduced pressure to afford the product as a brown solid. Yield:
308 mg (84%). 1H NMR (C6D6, 500.0 MHz, 298 K) δ: 7.24 (2 H,
d, J ) 7.6 Hz, m-Nb-2,6-C6H3Me2), 7.09 (1 H, m, m-Na-2,6-C6H3-
Me2), 7.04 (1 H, m, m-Na-2,6-C6H3Me2), 7.00 (2 H, t, J ) 7.6 Hz,
p-Nb-2,6-C6H3Me2, p-Na-2,6-C6H3Me2), 3.20 (1 H, apparent sept,
J ) 6.4 Hz, NCHaMeMe), 3.17 (1 H, apparent sept, J ) 6.4 Hz,
NCHbMeMe), 2.50 (6 H, s, Nb-2,6-C6H3Me2), 2.40 (3 H, s, Na-
2,6-C6H3MeMe), 2.07 (3 H, s, Na-2,6-C6H3MeMe), 1.83 (15 H, s,
C5Me5), 1.41 (3 H, s, MeCN2), 0.93 (3 H, d, J ) 6.4 Hz,
NCHaMeMe), 0.92 (3 H, d, J ) 6.4 Hz, NCHaMeMe), 0.75 (3 H,
d, J ) 6.4 Hz, NCHbMeMe), 0.55 (3 H, d, J ) 6.4 Hz, NCHb-
MeMe). 13C{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 166.3 (CN2),
153.3 (OCN), 148.3 (i-2,6-C6H3Me2), 148.2 (i-2,6-C6H3Me2), 134.0
(o-Na-2,6-C6H3Me2), 133.5 (o-Na-2,6-C6H3Me2), 130.1 (o-Nb-2,6-
C6H3Me2), 128.4 (p-Nb-2,6-C6H3Me2), 128.3 (p-Na-2,6-C6H3Me2),
127.7 (m-Na-2,6-C6H3Me2), 127.6 (m-Na-2,6-C6H3Me2), 124.6 (C5-
Me5), 121.0 (m-Nb-2,6-C6H3Me2), 49.6 (NCHaMeMe), 48.8 (NCHa-
MeMe), 25.1 (NCHbMeMe), 24.9 (NCHaMeMe), 24.6 (NCHb-
MeMe), 24.1 (NCHbMeMe), 20.4 (Nb-2,6-C6H3Me2), 19.6 (Na-2,6-
C6H3MeMe), 19.2 (Na-2,6-C6H3MeMe), 14.0 (MeCN2), 12.9 C5Me5).
IR (KBr plates, Nujol mull, cm-1): 2722 (w), 1610 (s), 1580 (s),
1495 (m), 1404 (w), 1338 (w), 1316 (m), 1302 (m), 1259 (w), 1226
(w), 1210 (m), 1192 (w), 1168 (w), 1114 (w), 1094 (w), 995 (m),
925 (m), 819 (w), 789 (w), 761 (m), 725 (m), 708 (w), 588 (w),
559 (w), 498 (w), 456 (m), 442 (m). Anal. Found (calc for C35H50N4-
OTi): C 71.2 (71.2); H 8.2 (8.5); N 9.4 (9.5). EIMS: m/z 591
[M]+, 575 [M - Me]+, 545 [M - 3Me]+.
Ti(η-C5Me5){N(Ar)C(NTol)O}{MeC(NiPr)2} (23). Ti(η-C5-
Me5)(NAr){MeC(NiPr)2} (565 mg, 1.28 mmol) was dissolved in
ca. 40 mL of pentane, to which was added 161 µL (170 mg, 1.28
mmol) of p-tolyl isocyanate via microliter syringe, and the resulting
solution was stirred for 18 h. A crop of dark brown crystals (362
mg, 49% yield) was isolated from the mother liquor. The remaining
solution had all volatiles removed under reduced pressure to afford
a further 262 mg (36% yield) of product as a brown powder. Total
yield: 624 mg (85%). 1H NMR (C6D6, 500.0 MHz, 298 K) δ: 7.66
(2 H, d, J ) 8.2 Hz, o-4-C6H4Me), 7.14 (2 H, d, J ) 8.2 Hz, m-4-
C6H4Me), 7.04 (1 H, d, J ) 7.2 Hz, o-2,6-C6H3Me2), 6.99 (1 H, d,
J ) 7.2 Hz, o-2,6-C6H3Me2), 6.95 (1 H, t, J ) 7.2 Hz, p-2,6-C6H3-
Me2), 3.26 (1 H, apparent sept, J ) 6.6 Hz, NCHaMeMe), 3.09 (1
H, apparent sept, J ) 6.4 Hz, NCHbMeMe), 2.37 (3 H, s,
4-C6H4Me), 2.21 (3 H, s, 2,6-C6H3MeMe), 2.02 (3 H, s, 2,6-C6H3-
MeMe), 1.96 (15 H, s, C5Me5), 1.43 (3 H, s, MeCN2), 1.07 (3 H,
d, J ) 6.6 Hz, NCHaMeMe), 0.97 (3 H, d, J ) 6.6 Hz, NCHa-
MeMe), 0.84 (3 H, d, J ) 6.4 Hz, NCHbMeMe), 0.56 (3 H, d, J )
6.4 Hz, NCHbMeMe). 13C{1H} NMR (C6D6, 125.7 MHz, 298 K)
δ: 167.9 (CN2), 154.9 (OCN), 148.3 (i-NAr), 147.9 (i-NAr), 133.7
(o-2,6-C6H3Me2), 133.4 (o-2,6-C6H3Me2), 129.4 (p-4-C6H4Me),
129.0 (m-4-C6H4Me), 128.6 (m-2,6-C6H3Me2), 128.3 (m-2,6-C6H3-
Me2), 128.1 (C5Me5), 125.6 (o-4-C6H4Me), 124.5 (p-2,6-C6H3Me2),
50.3 (NCHaMeMe), 49.3 (NCHbMeMe), 25.9 (NCHbMeMe), 24.8
(NCHaMeMe), 24.2 (NCHaMeMe), 24.0 (NCHbMeMe), 21.0 (2,6-
C6H3MeMe), 19.7 (4-C6H4Me), 19.4 (2,6-C6H3MeMe), 13.6 (MeCN2),

1184 Organometallics, Vol. 25, No. 5, 2006
Guiducci et al.
Ti(η-C5Me5){OC(NTol)N(Tol)C(NTol)O}{MeC(NiPr)2} (26).
Ti(η-C5Me5)(NTol){MeC(NiPr)2} (204 mg, 0.48 mmol) was dis-
solved in ca. 20 mL of benzene to give a dark green solution. To
this was added 120 µL (127 mg, 0.99 mmol) of p-tolyl isocyanate
via microliter syringe. The solution was observed to turn brown
and was stirred for 16 h. Volatiles were then removed under reduced
pressure to afford an oily red product. This was triturated with
pentane to yield a very static sensitive, dark brown solid. Yield:
171 mg (51%). 1H NMR (C6D6, 500.0 MHz, 298 K) δ: 7.61 (2 H,
d, J ) 8.6 Hz, o-Nb-4-C6H4Me), 7.16 (4 H, d, J ) 8.6 Hz, o-Na-
4-C6H4Me), 7.10 (2 H, d, J ) 8.6 Hz, m-Nb-4-C6H4Me), 7.02 (4
H, d, J ) 8.6 Hz, m-Na-4-C6H4Me), 3.43 (2 H, apparent sept, J )
7.1 Hz, NCHMeMe), 2.17 (6 H, s, Na-4-C6H4Me), 2.05 (3 H, s,
Nb-4-C6H4Me), 1.85 (15 H, s, C5Me5), 1.44 (3 H, s, MeCN2), 0.91
(6 H, d, J ) 7.1 Hz, NCHMeMe), 0.83 (6 H, d, J ) 6.8 Hz,
NCHMeMe). 13C{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 169.5
(CN2), 153.1 (i-Na-4-C6H4Me), 147.7 (p-Na-4-C6H4Me), 142.2 (i-
Nb-4-C6H4Me), 135.2 (p-Nb-4-C6H4Me), 130.0 (o-Nb-4-C6H4Me),
129.7 (m-Nb-4-C6H4Me), 129.4 (m-Na-4-C6H4Me), 128.6 (o-Na-4-
C6H4Me), 124.3 (C5Me5), 49.5 (NCHMeMe), 23.9 (NCHMeMe),
23.5 (NCHMeMe), 21.1 (Nb-4-C6H4Me), 21.0 (Na-4-C6H4Me), 16.4
(MeCN2), 12.31 (C5Me5). OC(N)(N) resonance not observed. IR
(KBr plates, Nujol mull, cm-1): 2728 (w), 2671 (w), 1882 (w),
1733 (w), 1655 (s), 1609 (m), 1572 (m), 1538 (s), 1505 (s), 1292
(m, br), 1209 (w), 1145 (w), 1107 (w), 1072 (w), 1021 (w), 998
(w), 946 (m), 891 (w), 813 (s), 791 (m), 723 (m), 670 (w), 638
(w), 616 (w), 584 (w), 549 (w), 519 (w), 442 (w), 417 (w), 407
(w). Anal. Found (calc for C41H53N5O2Ti): C 70.8 (70.8); H 7.8
(7.7); N 9.7 (10.1).
Ti(η-C5Me5){OC(NTol)N(Tol)C(NAr)O}{MeC(NiPr)2} (27).
A 83.6 mg (0.15 mmol) sample of Ti(η-C5Me5){N(Tol)C(NAr)O}-
{MeC(NiPr)2} was dissolved in a solution of 19.3 mg (0.15 mmol)
of p-tolyl isocyanate in ca. 5 mL of benzene to give a ruby solution.
After 30 min, volatiles were removed under reduced pressure, and
the final 1 mL of benzene was triturated with ca. 5 mL of pentane.
All remaining volatiles were removed under reduced pressure to
afford the product as a light brown powder. Yield: 84.3 mg (82%).
1H NMR (C6D6, 500.0 MHz, 298 K) δ: 7.61 (2 H, d, J ) 8.1 Hz,
o-Nb-C6H4Me), 7.15-7.13 (4 H, m, o-Na-C6H4Me, m-Na-C6H4Me),
7.04 (2 H, d, J ) 8.1 Hz, m-Nb-C6H4Me), 7.02 (1 H, m, m-2,6-
C6H3Me2), 6.94 (1 H, m, m-2,6-C6H3Me2), 6.86 (1 H, t, J ) 7.5
Hz, p-2,6-C6H3Me2), 3.50 (1 H, apparent sept, J ) 6.7 Hz, NCHa-
MeMe), 3.05 (1 H, apparent sept, J ) 6.7 Hz, NCHbMeMe), 2.35
(3 H, s (br), 2,6-C6H3MeMe), 2.23 (3 H, s, Na-C6H4Me), 2.14 (3
H, s, Nb-C6H4Me), 2.07 (3 H, s (br), 2,6-C6H3MeMe), 1.85 (15 H,
s, C5Me5), 1.51 (3 H, s, MeCN2), 1.06 (3 H, d, J ) 6.8 Hz,
NCHaMeMe), 1.01 (3 H, d, J ) 6.8 Hz, NCHaMeMe), 0.91 (3 H,
d, J ) 6.1 Hz, NCHbMeMe), 0.61 (3 H, d, J ) 6.1 Hz, NCHb-
MeMe). 13C{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 168.9 (CN2),
153.4 (i-Na-C6H4Me), 150.7 (i-2,6-C6H3Me2), 148.2 (o-2,6-C6H3-
Me2), 147.9 (p-Na-C6H4Me), 142.6 (p-Nb-C6H4Me), 135.3 (i-Nb-
C6H4Me), 130.7 (o-Nb-C6H4Me), 129.9 (C5Me5), 129.6 (o-2,6-
C6H3Me2), 129.4 (m-Nb-C6H4Me), 128.9 (m-Na-C6H4Me), 128.3 (m-
2,6-C6H3Me2), 127.9 (m-2,6-C6H3Me2), 124.2 (o-Na-C6H4Me),
121.1 (p-2,6-C6H3Me2), 50.5 (NCHaMeMe), 50.3 (NCHbMeMe),
26.4 (NCHbMeMe), 23.7 (NCHaMeMe), 23.6 (NCHaMeMe), 22.5
(NCHbMeMe), 21.2 (Nb-C6H4Me), 21.1 (Na-C6H4Me), 19.1 (2,6-
C6H3MeMe), 19.1 (2,6-C6H3MeMe), 14.0 (MeCN2), 12.7 (C5Me5).
OC(N)(N) resonances not observed. IR (KBr plates, Nujol mull,
cm-1): 2725 (w), 2360 (w), 2273 (w), 1637 (m), 1614 (m), 1597
(m), 1581 (s), 1507 (m), 1311 (m), 1261 (m), 1252 (m), 1202 (s),
1171 (w), 1127 (w), 1103 (w), 1070 (m), 1031 (w), 997 (m), 931
(w), 875 (w), 848 (w), 811 (w), 785 (w), 759 (w), 729 (m), 678
(w), 659 (w), 604 (w), 586 (w), 566 (w), 541 (w), 520 (w), 475
(m), 446 (m). Anal. Found (calc for C42H55N5O2Ti): C 71.3 (71.1);
H 7.6 (7.8); N 9.1 (9.9).
Ti(η-C5Me5){OC(O)N(Tol)C(NTol)O}{MeC(NiPr)2} (28). Ti-
(η-C5Me5){N(Tol)C(O)O}{MeC(NiPr)2} (29) (103 mg, 0.22 mmol)
was dissolved in ca. 15 mL of benzene to give a deep red solution.
To this was added 28.9 mg (0.22 mmol) of p-tolyl isocyanate in
ca. 5 mL of benzene to give a lighter red solution. After 10 min,
all volatiles were removed under reduced pressure, and the resulting
dark red oily solid was triturated with ca. 10 mL of pentane. The
product was afforded as a red-brown powder. Yield: 73 mg (55%).
1H NMR (C6D6, 500.0 MHz, 298 K) δ: 7.51 (2 H, d, J ) 8.0 Hz,
o-Na-4-C6H4Me), 7.08 (2 H, d, J ) 8.1 Hz, o-Nb-4-C6H4Me), 7.06*
(2 H, d, J ) 8.0 Hz, m-Na-4-C6H4Me), 7.02 (2 H, d, J ) 8.1 Hz,
m-Nb-4-C6H4Me), 3.47 (1 H, apparent sept, J ) 6.9 Hz, NCHa-
MeMe), 3.38 (1 H, apparent sept, J ) 6.9 Hz, NCHbMeMe), 2.17
(3 H, s, Nb-4-C6H4Me), 2.05 (3 H, s, Na-4-C6H4Me), 1.89 (15 H, s,
C5Me5), 1.36 (3 H, s, MeCN2), 1.10 (3 H, d, J ) 6.8 Hz,
NCHaMeMe), 1.09 (3 H, d, J ) 6.8 Hz, NCHaMeMe), 0.89 (3 H,
d, J ) 6.8 Hz, NCHbMeMe), 0.86* (3 H, d, J ) 6.8 Hz,
NCHbMeMe) (* indicates cross-peak in NOESY experiment). 13C-
{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 169.5 (CN2), 154.3
(OCO), 153.5 (i-Na-4-C6H4Me), 147.5 (p-Na-4-C6H4Me), 140.7 (p-
Nb-4-C6H4Me), 135.7 (i-Nb-4-C6H4Me), 130.4 (C5Me5), 129.6 (m-
Na-4-C6H4Me), 129.4 (o-Nb-4-C6H4Me), 127.5 (m-Nb-4-C6H4Me),
123.9 (o-Na-4-C6H4Me), 50.3 (NCHaMeMe), 49.9 (NCHbMeMe),
24.3 (NCHaMeMe), 23.9 (NCHbMeMe), 23.7 (NCHa,bMeMe), 21.1
(Na-4-C6H4Me), 21.0 (Nb-4-C6H4Me), 14.9 (MeCN2), 12.5 (C5Me5).
OC(N)(N) resonance not observed. IR (KBr plates, Nujol mull,
cm-1): 2955 (s), 2726 (w), 2272 (w), 1681 (m), 1618 (m), 1592
(m, br), 1507 (m), 1408 (w), 1258 (w), 1206 (w), 1183 (w), 1103
(w), 1068 (w), 1024 (w), 1001 (m), 933 (w), 883 (w), 859 (w),
812 (m), 788 (m), 736 (w), 723 (w), 680 (w), 643 (w), 604 (w),
587 (w), 545 (w), 533 (w), 474 (w), 445 (w). Anal. Found (calc
for C34H46N4O3Ti): C 67.2 (67.2); H 8.1 (7.6); N 8.5 (9.2).
Ti(η-C5Me5){OC(O)N(Tol)C(NAr)O}{MeC(NiPr)2} (30). A
44.5 mg (0.09 mmol) sample of Ti(η-C5Me5){N(Tol)C(O)O}{MeC-
(NiPr)2} was dissolved in ca. 5 mL of benzene. To this was added
a solution of 13.8 mg (0.09 mmol) of 2,6-dimethylphenyl isocyanate
in ca. 1 mL of benzene. After 18 h, volatiles were removed under
reduced pressure, and the final 0.5 mL of benzene was triturated
with ca. 2 mL of pentane. All remaining volatiles were removed
under reduced pressure to afford the product as a dark red solid.
Yield: 38 mg (65%). 1H NMR (C6D6, 500.0 MHz, 298 K) δ: 7.53
(2 H, d, J ) 8.1 Hz, o-4-C6H4Me), 7.13 (2 H, d, J ) 8.1 Hz, m-4-
C6H4Me), 7.03 (1 H, d (br), J ) 7.1 Hz, m-2,6-C6H3Me2), 6.93 (1
H, d (br), J ) 7.1 Hz, m-2,6-C6H3Me2), 6.87 (1 H, t, J ) 7.1 Hz,
p-2,6-C6H3Me2), 3.37 (1 H, apparent sept, J ) 6.6 Hz, NCHa-
MeMe), 3.02 (1 H, apparent sept, J ) 6.6 Hz, NCHbMeMe), 2.29
(3 H, s (br), 2,6-C6H3MeMe), 2.11 (3 H, s, C6H4Me), 1.99 (3 H, s
(br), 2,6-C6H3MeMe), 1.94 (15 H, s, C5Me5), 1.39 (3 H, s, MeCN2),
1.15 (3 H, d, J ) 6.6 Hz, NCHaMeMe), 1.08 (3 H, d, J ) 6.6 Hz,
NCHaMeMe), 0.85 (3 H, d, J ) 6.5 Hz, NCHbMeMe), 0.58 (3 H,
d, J ) 6.5 Hz, NCHbMeMe). 13C{1H} NMR (C6D6, 125.7 MHz,
298 K) δ: 169.1 (CN2), 154.2 (OCO), 151.2 (i-2,6-C6H3Me2), 147.5
(o-2,6-C6H3Me2), 140.8 (i-4-C6H4Me), 135.9 (p-4-C6H4Me), 131.1
(C5Me5), 129.5 (o-4-C6H4Me), 129.4 (m-4-C6H4Me), 128.9 (m-2,6-
C6H3Me2), 125.5 (m-2,6-C6H3Me2), 121.3 (p-2,6-C6H3Me2), 51.5
(NCHaMeMe), 51.0 (NCHbMeMe), 26.9 (NCHbMeMe), 24.2
(NCHaMeMe), 24.1 (NCHaMeMe), 23.4 (NCHbMeMe), 21.5 (4-
C6H4Me), 19.5 (2,6-C6H3MeMe), 19.3 (2,6-C6H3MeMe), 13.4
(C5Me5), 13.3 (MeCN2). OC(N)(N) resonance not observed. IR (KBr
plates, Nujol mull, cm-1): 2926 (s), 2725 (w), 1680 (s), 1620 (s),
1587 (s), 1514 (m, sh), 1313 (m), 1243 (m), 1203 (m), 1184 (m),
1105 (w), 1083 (w), 1025 (w), 1001 (s), 932 (w), 919 (w), 876
(w), 857 (w), 819 (m, br), 795 (m), 773 (m), 733 (w), 678 (w),
605 (w), 587 (w), 567 (w), 537 (w), 523 (w), 481 (w), 410 (w).
Anal. Found (calc for C35H48N4O3Ti): C 67.7 (67.3); H 7.8 (7.8);
N 9.0 (8.6).

Cyclopentadienyl-Amidinate Titanium Imido Compounds
Organometallics, Vol. 25, No. 5, 2006 1185
Ti(η-C5Me5){N(Ar)C(NTol)N(Tol)}{MeC(NiPr)2} (31). Ti(η-
C5Me5)(NAr){MeC(NiPr)2} (46.5 mg, 0.11 mmol) was dissolved
in 0.6 mL of C6D6. To this was added 23.4 mg (0.15 mmol) of
1,3-di-p-tolyl carbodiimide, and the reaction was monitored using
1H NMR spectroscopy. Complete formation of product was
observed after 24 h. Removal of all volatiles and trituration with
ca. 2 mL of pentane afforded the product as a dark brown powder.
was stirred for 16 h, after which a fine yellow precipitate was
observed. The supernatant was decanted off and the residue washed
with ca. 20 mL of pentane, to afford the product 15 as an insoluble
yellow powder (350 mg, 76% yield). The corresponding reaction
of 6 with nitrosobenzene was monitored by 1H NMR spectroscopy
and found to yield the corresponding dimeric oxo product 2.
NMR Tube Scale Reaction of Ti(η-C5Me5)(NAr){MeC-
(NiPr)2} (9) with Nitrosobenzene. A 16.0 mg (0.04 mmol) sample
of Ti(η-C5Me5)(NAr){MeC(NiPr)2} (9) was dissolved in 0.6 mL
of C6D6. To this was added 3.9 mg (0.04 mmol) of nitrosobenzene,
resulting in an immediate color change from green to orange. The
1
Yield: 50.2 mg (72%). H NMR (C6D6, 500.0 MHz, 298 K) δ:
7.41 (2 H, d (br), m-Na-4-C6H4Me), 7.01 (2 H, d, o-Na-4-C6H4-
Me), 6.79 (1 H, m, p-N-2,6-Me2C6H3), 6.72 (2 H, d, m-Nb-4-C6H4-
Me), 6.67 (2 H, m, m-N-2,6-Me2C6H3), 6.62 (2 H, d, o-Nb-4-
C6H4Me), 3.89 (1 H, apparent sept, NCHaMeMe), 3.11 (1 H,
apparent sept, NCHbMeMe), 2.26 (3 H, s, Na-4-C6H4Me), 2.19 (6
H, s, N-2,6-C6H3Me2), 2.07 (3 H, s, Nb-4-C6H4Me), 1.81 (15 H, s,
C5Me5), 1.56 (3 H, s, MeCN2), 1.15 (3 H, d, J ) 6.8 Hz,
NCHaMeMe), 1.06 (3 H, d, J ) 6.8 Hz, NCHaMeMe), 0.89 (3 H,
d, J ) 6.8 Hz, NCHbMeMe), 0.31 (3 H, s (br), NCHbMeMe). 13C-
{1H} NMR (C6D6, 125.7 MHz, 298 K) δ: 166.6 (MeCN2), 149.9
(o-2,6-Me2C6H3), 149.0 (i-Na-4-C6H4Me), 147.9 (m-,p-2,6-Me2C6H3),
133.6 (o-2,6-Me2C6H3), 131.4 (p-Na-4-C6H4Me), 128.4 (m-Na-4-
C6H4Me), 128.3 (i-Nb-4-C6H4Me), 128.1 (o-Na-4-C6H4Me), 127.4
(p-Nb-4-C6H4Me), 127.2 (o-Nb-4-C6H4Me), 126.8 (C5Me5), 121.1
(m-Nb-4-C6H4Me), 50.1 (NCHaMeMe), 49.0 (NCHbMeMe), 24.8
(NCHbMeMe), 24.7 (NCHaMeMe), 23.9 (NCHbMeMe), 23.0 (NCHa-
MeMe), 21.0 (Nb-4-C6H4Me), 20.9 (2,6-C6H3MeMe), 20.4 (Na-4-
C6H4Me), 19.5 (2,6-C6H3MeMe), 18.6 (MeCN2), 12.8 (C5Me5). IR
(KBr plates, Nujol mull, cm-1): 2728 (w), 2671 (w), 1882 (w),
1733 (w), 1655 (s), 1609 (m), 1572 (m), 1538 (s), 1505 (s), 1292
(m, br), 1209 (w), 1145 (w), 1107 (w), 1072 (w), 1021 (w), 998
(w), 946 (m), 891 (w), 813 (s), 791 (m), 723 (m), 670 (w), 638
(w), 616 (w), 584 (w), 549 (w), 519 (w), 442 (w), 417 (w), 407
(w). Anal. Found (calc for C41H55N5Ti): C 72.7 (74.0); H 8.6 (8.3);
N 10.2 (10.5).
1
1
reaction was monitored using H NMR spectroscopy, and the H
NMR spectrum was found to contain resonances attributable to the
dimeric oxo compound 2 and tBuNdNAr. A corresponding reaction
was also carried out for Ti(η-C5Me5)(NTol){MeC(NiPr)2} (10).
Ti(η-C5Me5){N(Tol)C(Ph)2O}{MeC(NiPr)2} (33). A 7.0 mg
(0.02 mmol) sample of Ti(η-C5Me5)(NTol){MeC(NiPr)2} (10), 3.0
mg (0.02 mmol) of benzophenone, and 1.9 mg (0.01 mmol) of 1,4-
dimethoxybenzene (internal standard) were dissolved in 592 mg
1
of toluene-d8. The reaction was monitored using H NMR spec-
troscopy in the temperature range 16 to -40 °C. Upon cooling of
the solution to -40 °C, Ti(η-C5Me5){N(Tol)C(Ph)2O}{MeC(Ni-
Pr)2} (33) was afforded in ca. 100% yield by 1H NMR spectroscopy.
1H NMR (toluene-d8, 500.0 MHz, 233 K) δ: 8.05-8.03 (2 H, m,
o-4-C6H4Me), 7.70 (2 H, d, J ) 7.6 Hz, o-C6H5 (a)), 7.37-7.35 (2
H, m, o-C6H5 (b)), 7.21-7.19 (2 H, m, m-4-C6H4Me), 7.13 (1 H,
t, J ) 7.6 Hz, p-C6H5 (a)), 7.10-7.07 (3 H, m, m-, p-C6H5 (b)),
7.05-7.01 (2 H, m, m-C6H5 (a)), 4.14 (1 H, apparent sept, J ) 7.0
Hz, NCHaMeMe), 3.55 (1 H, apparent sept, J ) 7.0 Hz, NCHb-
MeMe), 2.16 (3 H, s, 4-C6H4Me), 1.95 (15 H, s, C5Me5), 1.67 (3
H, s, MeCN2), 1.30 (3 H, d, J ) 7.0 Hz, NCHaMeMe), 1.19 (3 H,
d, J ) 7.0 Hz, NCHbMeMe), 0.96 (3 H, d, J ) 7.0 Hz, NCHb-
MeMe), 0.72 (3 H, d, J ) 7.0 Hz, NCHaMeMe).
Ti(η-C5Me5){N(Tol)C(NTol)N(Tol)}{MeC(NiPr)2} (32). A
19.0 mg (0.04 mmol) sample of Ti(η-C5Me5)(NTol){MeC(NiPr)2}
was dissolved in 0.6 mL of C6D6. To this was added 9.8 mg (0.04
mmol) of 1,3-di-p-tolyl carbodiimide, resulting in an immediate
color change from dark green to dark brown. The reaction was
Ti(η-C5Me5){N(tBu)C(Ph)(H)O}{MeC(NiPr)2} (34). Ti(η-C5-
Me5)(NtBu){MeC(NiPr)2} (6) (20.4 mg, 0.05 mmol) was dissolved
in 0.6 mL of C6D6, and to this was added 5.0 µL (5.2 mg, 0.05
mmol) of benzaldehyde via microliter syringe. After 5 min, [Ti-
(η-C5Me5){N(tBu)C(Ph)(H)O}{MeC(NiPr)2}] (34) was afforded in
1
1
1
monitored using H NMR spectroscopy and was found to go to
ca. 100% yield by H NMR spectroscopy. H NMR (C6D6, 500.0
MHz, 289 K) δ: 7.39 (2 H, d, J ) 7.1 Hz, o-C6H5), 7.20-7.08 (3
H, m, m-, p-C6H5), 6.01 (1 H, s, OC(H)), 3.90 (1 H, apparent sept,
J ) 6.8 Hz, NCHaMeMe), 3.58 (1 H, apparent sept, J ) 6.8 Hz,
NCHbMeMe), 2.01 (15 H, s, C5Me5), 1.73 (3 H, s, MeCN2), 1.31
(3 H, d, J ) 6.8 Hz, NCHaMeMe), 1.24 (3 H, d, J ) 6.8 Hz, NCHa-
MeMe), 1.12 (3 H, d, J ) 6.8 Hz, NCHbMeMe), 1.09 (9 H, s, tBu),
1.01 (3 H, d, J ) 6.5 Hz, NCHbMeMe).
completion after 1 h. Removal of all volatiles under reduced
pressure and trituration with pentane afforded the product as a
brown powder. Yield: 21 mg (73%). 1H NMR (C6D6, 500.0 MHz,
298 K) δ: 7.24 (4 H, d (br), m-Na-4-C6H4Me), 6.97 (2 H, d, J )
8.3 Hz, m-Nb-4-C6H4Me), 6.92 (4 H, d, J ) 7.8 Hz, o-Na-4-C6H4-
Me), 6.85 (2 H, d, J ) 8.3 Hz, o-Nb-4-C6H4Me), 3.69 (2 H, apparent
sept, J ) 7.1 Hz, NCHMeMe), 2.11 (6 H, s, Na-4-C6H4Me), 2.02
(3 H, s, Nb-4-C6H4Me), 1.87 (15 H, s, C5Me5), 1.54 (3 H, s,
MeCN2), 1.02 (6 H, d, J ) 7.1 Hz, NCHMeMe), 0.73 (6H, d, J )
7.1 Hz, NCHMeMe). 13C{1H} NMR (C6D6, 125.7 MHz, 298 K)
δ: 173.6 (N2CN), 166.6 (MeCN2), 149.7 (i-Nb-4-C6H4Me), 148.3
(p-Nb-4-C6H4Me), 147.6 (i-Na-4-C6H4Me), 130.1 (p-Na-4-C6H4Me),
128.6 (o-Nb-4-C6H4Me), 128.3 (o-Na-4-C6H4Me), 127.7 (C5Me5),
123.8 (m-Na-4-C6H4Me), 122.6 (m-Nb-4-C6H4Me), 49.3 (NCH-
MeMe), 24.1 (NCHMeMe), 23.1 (NCHMeMe), 20.9 (Na-4-
C6H4Me), 20.9 (Nb-4-C6H4Me), 18.8 (MeCN2), 12.7 (C5Me5). IR
(KBr plates, Nujol mull, cm-1): 2728 (w), 2671 (w), 1882 (w),
1733 (w), 1655 (s), 1609 (m), 1572 (m), 1538 (s), 1505 (s), 1292
(m, br), 1209 (w), 1145 (w), 1107 (w), 1072 (w), 1021 (w), 998
(w), 946 (m), 891 (w), 813 (s), 791 (m), 723 (m), 670 (w), 638
(w), 616 (w), 584 (w), 549 (w), 519 (w), 442 (w), 417 (w), 407
(w). Anal. Found (calc for C40H53N5Ti): C 73.1 (73.7); H 8.7 (8.2);
N 10.8 (10.8).
Ti(η-C5Me5){N(Tol)C(Ph)(H)O}{MeC(NiPr)2} (35a/35b). A
7.5 mg (0.02 mmol) sample of Ti(η-C5Me5)(NTol){MeC(NiPr)2}
(10) was dissolved in 0.6 mL of C6D6. To this was added 1.8 µL
(1.9 mg, 0.02 mmol) of benzaldehyde via microliter syringe, and
the reaction was monitored using 1H NMR spectroscopy. Complete
conversion of the starting materials to form the product, presumed
to be 35a, was observed after 5 min. This compound was found to
interconvert to another product, presumed to be 35b, with a half-
life of ca. 15 min. Decomposition of this compound to the oxo
species [Ti(η-C5Me5)(µ-O){MeC(NiPr)2}]2 (2) prevented isolation
and full characterization of the species. 35a: 1H NMR (C6D6, 500.0
MHz, 289 K) δ: 7.40 (2 H, d, J ) 6.8 Hz, o-C6H5), 7.15-7.10 (3
H, m, m-, p-C6H5), 6.93 (2 H, d, J ) 8.5 Hz, o-4-C6H4Me), 6.65
(2 H, d, J ) 8.5 Hz, m-4-C6H4Me), 6.18 (1 H, s, OC(H)), 4.14 (1
H, apparent sept, J ) 7.0 Hz, NCHaMeMe), 3.54 (1 H, apparent
sept, J ) 7.0 Hz, NCHbMeMe), 2.13 (3 H, s, 4-C6H4Me), 1.97 (15
H, s, C5Me5), 1.58 (3 H, s, MeCN2), 1.25 (3 H, d, J ) 7.1 Hz,
NCHaMeMe), 1.12 (3 H, d, J ) 6.6 Hz, NCHbMeMe), 0.93 (3 H,
d, J ) 7.0 Hz, NCHaMeMe), 0.81 (3 H, d, J ) 6.8 Hz, NCHb-
MeMe). 35b: 1H NMR (C6D6, 500.0 MHz, 289 K) δ: 7.22 (2 H,
m, o-C6H5), 7.15-7.10 (3 H, m, m-,p-C6H5), 6.84 (2 H, d, J ) 8.5
Reaction of Ti(η-C5Me5)(NtBu){PhC(NSiMe3)2} (5) with Ni-
trosobenzene. A 740 mg (1.43 mmol) sample of Ti(η-C5Me5)-
(NtBu){PhC(NSiMe3)2} (5) was dissolved in ca. 30 mL of pentane,
and to this was added a solution of 155 mg (1.45 mmol) of
nitrosobenzene dissolved in ca. 15 mL of pentane. The reaction

1186 Organometallics, Vol. 25, No. 5, 2006
Guiducci et al.
Table 4. X-ray Data Collection and Processing Parameters for Ti(η-C5Me5)(NAr){MeC(NiPr)2} (9),
[Ti(η-C5Me5)(µ-S){PhC(NSiMe3)2}]2 (11), [Ti(η-C5H4Me)(µ-S){PhC(NSiMe3)2}]2 (13), and
Ti(η-C5Me5){N(Ar)C(NR)O}{MeC(NiPr)2} (R ) Ar (22) or Tol (23))
9
11
13
22
23
empirical formula
fw
temp/K
C26H41N3Ti
443.53
150
C46H76N4S2Si4Ti2
957.4
150
C38H60N4S2Si4Ti2
845.18
175
C35N50N4O1Ti1
590.71
150
C34H48N4O1Ti1
575.68
150
wavelength/Å
space group
a/Å
b/Å
c/Å
0.71073
I41cd
20.5223(4)
20.5223(4)
24.3873(6)
90
90
90
10271.1
16
1.15
0.71073
C2/m
20.5239(8)
14.2637(7)
10.5071(4)
90
104.031(3)
90
2984.2
2
1.07
0.44
R1 ) 0.0744
Rw ) 0.0900
0.71069
P1h
0.71073
P21/c
19.0867(9)
9.8270(4)
17.7637(7)
90
93.316(2)
90
3326.3(2)
4
1.18
0.29
R1 ) 0.0591
Rw ) 0.0608
0.71073
P1h
9.416(1)
10.684(2)
12.409(2)
93.934(6)
94.552(8)
115.495(8)
1115.9
9.5758(3)
9.9197(3)
17.2651(6)
82.229(1)
78.344(1)
84.112(1)
1586.63(9)
2
R/deg
â/deg
γ/deg
V/Å3
Z
1
1.26
0.58
0.0636
d(calcd)/Mg‚m-3
abs coeff/mm-1
R indices R1, Rw
[I > 3σ(I)]a
1.20
0.30
0.0890
0.0919
0.35
R1 ) 0.0396
Rw ) 0.0418
0.0534
2
a R1 ) ∑||Fo| - |Fc||/∑|Fo|; Rw ) x{∑w(|Fo| - |Fc|)2/∑(w|Fo| }.
Hz, o-4-C6H4Me), 6.67 (2 H, d, J ) 8.5 Hz, m-4-C6H4Me), 6.24
(1 H, s, OC(H)), 3.30 (1 H, apparent sept, J ) 6.4 Hz, NCHa-
MeMe), 3.25 (1 H, apparent sept, J ) 6.4 Hz, NCHbMeMe), 2.10
(3 H, s, 4-C6H4Me), 2.04 (15 H, s, C5Me5), 1.65 (3 H, d, J ) 6.7
Hz, NCHaMeMe), 1.14 (3 H, d, J ) 6.7 Hz, NCHaMeMe), 1.12 (3
H, s, MeCN2), 1.04 (3 H, d, J ) 6.6 Hz, NCHbMeMe), 0.85 (3 H,
d, J ) 6.4 Hz, NCHbMeMe).
Crystal Structure Determinations of Ti(η-C5Me5)(N-2,6-
C6H3Me2){MeC(NiPr)2} (9), [Ti(η-C5Me5)(µ-S){PhC(NSiMe3)2}]2
(11), [Ti(η-C5H4Me)(µ-S){PhC(NSiMe3)2}]2 (13), and Ti(η-
C5Me5){N(Ar)C(NR)O}{MeC(NiPr)2} (R ) Ar (22) or Tol (23)).
Crystal data collection and processing parameters are given in Table
4. Crystals were mounted on a glass fiber using perfluoropolyether
oil and cooled rapidly to 150 or 175 K in a stream of cold N2 using
an Oxford Cryosystems CRYOSTREAM unit. Diffraction data were
measured using either an Enraf-Nonius DIP2000 or KappaCCD
diffractometer. Intensity data were processed using the DENZO
package.110 The structures were solved with SIR92,111 and subse-
quent full-matrix least-squares refinements were carried out using
CRYSTALS.112 For 9 the choice of space group as C2/m over the
possible non-centrosymmetric alternatives was favored by examina-
tion of the normalized structure factors with the expected values
and by the satisfactory refinement in C2/m. Coordinates and
anisotropic thermal parameters of all non-hydrogen atoms were
refined. Hydrogen atoms were placed in calculated positions. A
full listing of atomic coordinates, bond lengths and angles, and
displacement parameters for the eight structures has been deposited
at the Cambridge Crystallographic Data Center. See Notice to
Authors, Issue No. 1.
Ti(η-C5Me5){N(Tol)C(Ph)(Me)O}{MeC(NiPr)2} (36). A 182
mg (0.43 mmol) sample of Ti(η-C5Me5)(NTol){MeC(NiPr)2} (10)
was dissolved in ca. 5 mL of benzene. To this was added a solution
of 49.6 µL (51.1 mg, 0.43 mmol) of acetophenone in ca. 5 mL of
benzene to afford a dark brown solution. After 15 min all volatiles
were removed under reduced pressure, and the residue was triturated
with ca. 5 mL of pentane to afford the product as a dark brown
1
wax. Yield: 132 mg (57%). H NMR (C6D6, 500.0 MHz, 289 K)
δ: 7.37 (2 H, d, J ) 8.1 Hz, o-C6H5), 7.18-7.13 (1 H, m, p-C6H5),
7.08 (2 H, m, m-C6H5), 6.89 (2 H, d, J ) 8.1 Hz, o-4-C6H4Me),
6.53 (2 H, d, J ) 8.1 Hz, m-4-C6H4Me), 6.18 (1 H, s, OC(H)),
4.10 (1 H, apparent sept, J ) 6.7 Hz, NCHaMeMe), 3.10 (1 H,
apparent sept, J ) 6.7 Hz, NCHbMeMe), 2.14 (3 H, s, 4-C6H4Me),
2.06 (15 H, s, C5Me5), 2.05 (3 H, s, OCMe), 1.53 (3 H, s, MeCN2),
1.25 (3 H, d, J ) 6.7 Hz, NCHaMeMe), 1.12 (3 H, d, J ) 6.7 Hz,
NCHaMeMe), 0.93 (3 H, d, J ) 6.7 Hz, NCHbMeMe), 0.81 (3 H,
d, J ) 6.7 Hz, NCHbMeMe). 13C{1H} NMR (C6D6, 125.7 MHz,
289 K) δ: 164.3 (CN2), 148.6 (i-/p-4-C6H4Me), 148.1 (p-/i-4-C6H4-
Me), 128.9 (o-4-C6H4Me), 128.5 (i-C6H5), 128.4 (p-C6H5), 127.6
(o-C6H5), 127.1 (m-C6H5), 124.3 (C5Me5), 118.4 (m-4-C6H4Me),
84.1 (OCMe), 49.1 (NCHbMeMe), 48.2 (NCHaMeMe), 25.4
(OCMe), 24.5 (NCHbMeMe), 24.4 (NCHaMeMe), 23.6 (NCHb-
MeMe), 23.2 (NCHaMeMe), 20.7 (4-C6H4Me), 16.6 (MeCN2), 12.4
(C5Me5). IR (KBr plates, Nujol mull, cm-1): 1654 (m), 1636 (m),
1610 (m), 1578 (w), 1505 (s), 1311 (m), 1288 (m), 1262 (m), 1206
(w), 1171 (w), 1115 (m), 1088 (m), 1071 (m), 1027 (m), 914 (w),
899 (w), 841(w), 792 (m), 763 (w), 735 (w), 723 (w), 697 (w),
669 (w), 655 (w), 628 (w), 610 (w), 594 (w), 572 (w), 527 (w),
498 (w), 435 (w), 402 (w).
Computational Details. All calculations were performed with
the Gaussian 98 set of programs113 within the framework of hybrid
DFT (B3PW91).114,115 The Ti atom was represented with the small
core RECP from the Stuttgart’s group and the associated basis set.116
The remaining atoms (C, H, N, O) were represented by a 6-31G-
(d,p) basis set.117 The nature of the extrema located after geometry
(110) Otwinowski, Z.; Minor, W. Processing of X-ray Diffraction Data
Collected in Oscillation Mode; Academic Press: New York, 1997.
(111) Altomare, A.; Cascarano, G.; Carrithers, J. R.; Betteridge, P. W.;
Cooper, R. I. J. Appl. Crystallogr. 1994, 27, 435.
(112) Watkin, D. J.; Prout, C. K.; Carruthers, J. R.; Betteridge, P. W.;
Cooper, R. I. CRYSTALS; Chemical Crystallography Laboratory: Oxford,
UK, 2001.
(113) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Zakrzewski, V. G.; Montgomery, J. J. A.;
Stratmann, R. E.; Burant, J. C.; Dapprich, S.; Millam, J. M.; Daniels, A.
D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J.; Barone, V.; Cossi,
M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.; Clifford, S.;
Ochterski, J.; Petersson, G. A.; Ayala, P. Y.; Cui, Q.; Morokuma, K.; Malick,
D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Cioslowski, J.;
Ortiz, J. V.; Baboul, A. G.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz,
P.; Komaromi, I.; Gomperts, R.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-
Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Gonzalez, C.; Challacombe,
M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Andres, J. L.;
Head-Gordon, M.; Replogle, E. S.; Pople, J. A. Gaussian 98; 1998.
(114) Becke, A. D. J. Chem. Phys. 1992, 98, 5648.
NMR Tube Scale Reactions of Ti(η-C5Me5)(NtBu){MeC-
(NiPr)2} (6) with Benzamide, Hexanoamide, and Trimethyl-
acetamide. Ti(η-C5Me5)(NtBu){MeC(NiPr)2} (6) (10.1 mg, 5.1 ×
10-5 mol) was dissolved in CD2Cl2 (0.6 mL), and the resulting red
solution was used to dissolve 1.5 equiv of dimethoxybenzene (5.6
mg, 7.7 × 10-5 mol) and 1.0 equiv of benzamide (3.7 mg, 5.1 ×
10-5 mol). The mixture was transferred to an NMR tube equipped
1
with a J. Young Teflon valve, and the H NMR spectrum was
recorded over 24 h. Anolgous procedures were followed for
screening reactions with other metal compounds and hexanoamide
and trimethylacetamide.
(115) Perdew, J. P.; Wang, Y. Phys. ReV. B 1992, 45, 13244.
(116) Andrae, D.; Ha¨ussermann, U.; Dolg, M.; Stoll, H.; Preuss, H. Theor.
Chim. Acta 1990, 77, 123.

Cyclopentadienyl-Amidinate Titanium Imido Compounds
Organometallics, Vol. 25, No. 5, 2006 1187
optimization without any symmetry constraint has been determined
by analytic calculations of the vibrational frequencies.
Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations and further details
of the DFT calculations. This material is available free of charge
via the Internet at http://pubs.acs.org.
Acknowledgment. We thank the EPSRC for support and
Dr. E. Clot for the DFT calculations.
(117) Hariharan, P. C.; Pople, J. A. Theor. Chim. Acta 1973, 28, 213.
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