Titanium(II), -(III), and -(IV) complexes supported by benzamidinate ligands

Article abstract of DOI:10.1021/om970933c

The synthesis and reactivity of a wide range of titanium benzamidinates is described. Addition of 0.5 equiv of Me₂Mg to the dichloride L₂TiCl₂ (L = PhC(NSiMe₃)₂) in Et₂O yields the chloro-a

Full text of DOI:10.1021/om970933c

Organometallics 1998, 17, 1355-1368
1355
Tita n iu m (II), -(III), a n d -(IV) Com p lexes Su p p or ted by
Ben za m id in a te Liga n d s
J ohn R. Hagadorn and J ohn Arnold*
Department of Chemistry, University of California, Berkeley, California 94720-1460
Received October 27, 1997
The synthesis and reactivity of a wide range of titanium benzamidinates is described.
Addition of 0.5 equiv of Me2Mg to the dichloride L2TiCl2 (L ) PhC(NSiMe3)2) in Et2O yields
the chloro-alkyl derivative L2Ti(Me)Cl in good yield. The addition of 2 equiv of PhCH2-
MgCl to the dichloride affords thermally sensitive L2Ti(CH2Ph)2 in moderate yield. Likewise,
addition of 1 equiv of Me2Mg results in the clean formation of the dimethyl L2TiMe2. The
dimethyl reacts with tert-butylamine in refluxing benzene to form the five-coordinate imido
L2TiNCMe3, for which crystallographic data is presented. The imido reacts with acetone in
C6D6 to form the bridging oxo derivative L2Ti(µ-O)2TiL[η1-NC(Ph)N(SiMe3)2]. Overnight
reduction of the dichloride with 1% Na/Hg amalgam in tetrahydrofuran (THF) forms the
Ti(III) derivative L2TiCl(THF), which is crystallized from hexanes in moderate yield.
Carrying out the analogous reduction in toluene yields the base-free Ti(III) chloride, L2-
TiCl, for which crystallographic data is presented. Allowing the reaction (in toluene) to
proceed for an additional 48 h results in further reduction and the formation of the end-on
bound dinitrogen complex (L2Ti)2(µ-N2), which is isolated as dark blue crystals from hexanes
in moderate yield. Reduction of L2Ti(Me)Cl with 1% Na/Hg amalgam in THF forms the
Ti(III) methyl derivative which is isolated as the five-coordinate THF-free product L2TiMe
upon evacuation and crystallization from hexamethyldisiloxane (HMDSO). The related Ti-
(III) alkyl L2TiCH2SiMe3 is readily prepared by reaction of LiCH2SiMe3 with L2TiCl in
toluene. Carrying out the 1% Na/Hg amalgam reduction of the dichloride in the presence
of CO results in the formation of the Ti(III) bridging-oxo species (L2Ti)2(µ-O), which is isolated
in low yield. CO as the sole oxygen source is confirmed by the use of C18O, which yielded
only labeled product. Analogous reduction in the presence of N,N,N′,N′-tetramethylethyl-
enediamine (TMEDA) results in the C-N bond cleavage of an amidinate ligand and the
cyclometalation of TMEDA. Two products, L2TiNSiMe3 and LTi[η2-Me3SiNC(H)Ph][η3-
CH2N(Me)CH2CH2NMe2], are isolated in good yields by fractional crystallization from
hexanes. The dinitrogen complex, (L2Ti)2(µ-N2), reacts with pyridine (Py) and 2,6-
dimethylphenyl isocyanide (XylylNC) to form base adducts [L2Ti(Py)]2(µ-N2) and [L2Ti-
(CNXylyl)]2(µ-N2) without loss of the dinitrogen ligand. Crystallographic data for the Py
adduct is presented. Oxidation reactions of (L2Ti)2(µ-N2) with a variety of oxygen and sulfur
sources is reported. Reaction with dry O2 in the presence of pyridine gives the seven-
coordinate peroxo complex L2Ti(η2-O2)Py. The related reaction with excess S8 yields the
dark-green persulfido derivative L2Ti(η2-S2), for which crystallographic data is presented.
The persulfido reacts overnight with Hg in toluene solution to give the bimetallic sulfido
complex L2Ti(µ-S)2TiL[η1-NC(Ph)N(SiMe3)2], which is formed following a silyl-group migra-
tion. The analogous oxygen-containing product is best prepared by the reaction of powdered
(L2Ti)(µ-N2) with dry O2. In the presence of excess pyridine, L2Ti(η2-S2) reacts with Hg to
yield the terminal sulfido L2Ti(S)Py. The crystallographically characterized terminal-oxo
derivative L2Ti(O)OPy is prepared by reaction of (L2Ti)(µ-N2) with an excess of pyridine
N-oxide in toluene-pyridine.
In tr od u ction
transition-metal derivatives, supporting ligands are
generally bulky in order to provide adequate steric
shielding for the prevention of unwanted bimolecular
reactivity and must provide the necessary electronic
stabilization to the metal center. Studies utilizing a
wide range of ligands have confirmed the influence of
the ancillary ligand environment on reactivity, but the
accurate prediction of reactivity from the structure
remains a challenging problem. For the group 4 triad,
In recent years, there has been considerable effort put
forth in developing supporting ligands in transition-
metal chemistry, with a major goal being the tailoring
of chemical reactivity and properties.1,2 For monomeric
(1) Cotton, F. A.; Wilkinson, G. Advanced Inorganic Chemistry, 5th
ed.; Wiley: New York, 1988.
(2) Elschenbroich, C.; Salzer, A. Organometallics, A Concise Intro-
duction, 2nd ed.; VCH: Weinheim, 1992.
S0276-7333(97)00933-3 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 03/05/1998

1356 Organometallics, Vol. 17, No. 7, 1998
Hagadorn and Arnold
Sch em e 1
much of this research has been fundamental in nature
but recently intense effort has been focused on com-
plexes which serve as precursors to olefin polymeriza-
tion catalysts. Toward these ends, complexes incorpo-
rating N-donor ligands such as amidos3-13 and N4-
macrocycles14-20 have shown considerable promise.
We are interested in the use of amidinate ligands in
transition-metal chemistry. In the course of our studies,
we have explored several general classes of amidinate
systems including linked bis(amidinates)21 and fer-
rocene-containing derivatives.22 Here, we report chem-
istry that deals exclusively with the N,N′-bis(trimeth-
ylsilyl)benzamidinate (BTBA) ligand.23 We found its
use particularly attractive because as the ligand is
prepared easily and cheaply on a large scale, its
complexes are nicely soluble and generally highly
crystalline and the ligand displays excellent NMR
spectroscopic properties. Well-characterized BTBA com-
plexes are known for a wide range of transition metals
in various oxidation states across the periodic table. For
titanium, a pair of Ti(IV) chloride derivatives were first
reported in 1988 by Roesky24 and Dehnicke.25 Since
then several workers have utilized these ligands for the
stabilization of olefin polymerization catalysts,26-30 some
containing mixed cyclopentadienyl-amidinate ligand
arrays.31-33 Other workers have studied low-valent
derivatives34,35 and imidos36 and have shown the utility
of µ-formamidinate ligands for the preparation of com-
plexes containing dititanium cores.35,37 Here, we present
our studies of Ti(IV) alkyl and imido derivatives, the
reduction chemistry of L2TiCl2 leading to a variety of
bond cleavages, and the reactivity of a dinitrogen
complex with Lewis-bases and oxygen/sulfur sources.
Portions of this work were communicated in preliminary
reports.38-40
Resu lts a n d Discu ssion
(3) Burger, V. H.; Wiegel, K. Z. Anorg. Allg. Chem. 1973, 398, 257.
(4) Andersen, R. A. Inorg. Chem. 1979, 18, 2928.
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2, 16.
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Bercaw, J . E. J . Am. Chem. Soc. 1994, 116, 4623.
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1996, 15, 923.
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Soc. 1996, 118, 591.
Alk yl a n d Im id o Der iva tives. The starting mate-
rial for our investigations presented here is the Ti(IV)
dichloride L2TiCl2, which was first synthesized and
(24) Roesky, H. W.; Meller, B.; Noltemeyer, M.; Schmidt, H. G.;
Scholz, U.; Sheldrick, G. M. Chem. Ber. 1988, 121, 1403.
(25) Fenske, D.; Hartmann, E.; Dehnicke, K. Z. Naturforsch. 1988,
43b, 1611.
(26) For Al-based ethylene polymerization catalysts supported by
amidinates, see: Coles, M. P.; J ordan, R. F. J . Am. Chem. Soc. 1997,
119, 8125.
(10) Schrock, R. R.; Cummins, C. C.; Wilhelm, T.; Lin, S.; Reid, S.
M.; Kol, M.; Davis, W. M. Organometallics 1996, 15, 1470.
(11) Scollard, J . D.; McConville, D. H. J . Am. Chem. Soc. 1996, 118,
10008.
(27) Flores, J . C.; Chien, J . C. W.; Rausch, M. D. Organometallics
1995, 14, 1827.
(12) Warren, T. H.; Schrock, R. R.; Davis, W. M. Organometallics
1996, 15, 562.
(13) Tsuie, B.; Swenson, D. C.; J ordan, R. F.; Petersen, J . L.
Organometallics 1997, 16, 1392.
(28) Flores, J . C.; Chien, J . C. W.; Rausch, M. D. Organometallics
1995, 14, 2106.
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503, 307.
(14) Goedken, V. L.; Ladd, J . A. J . Chem. Soc., Chem. Commun.
1982, 142.
(15) Cotton, F. A.; Czuchajowska, J . Polyhedron 1990, 9, 2553.
(16) Housmekerides, 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.
(30) Walther, D.; Fischer, R.; Gorls, H.; Koch, J .; Schweder, B. J .
Organomet. Chem. 1996, 508, 13.
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Chem. Commun. 1993, 1415.
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Commun. 1994, 2607.
(17) Brand, H.; Arnold, J . Angew. Chem., Int. Ed. Engl. 1994, 33,
95.
(33) Gomez, R.; Duchateau, R.; Chernega, A. N.; Teuben, J . H.;
Edelmann, F. T.; Green, M. L. H. J . Organomet. Chem. 1995, 491, 153.
(34) Dick, D. G.; Duchateau, R.; Edema, J . H.; Gambarotta, S. Inorg.
Chem. 1993, 32, 1959.
(35) Cotton, F. A.; Wojtczak, W. A. Polyhedron 1994, 13, 1337.
(36) Stewart, P. J .; Blake, A. J .; Mountford, P. Inorg. Chem. 1997,
36, 3616.
(37) Hao, S. K.; Feghali, K.; Gambarotta, S. Inorg. Chem. 1997, 36,
3390.
(38) Hagadorn, J . R.; Arnold, J . Organometallics 1994, 13, 4670.
(39) Hagadorn, J . R.; Arnold, J . J . Am. Chem. Soc. 1996, 118, 893.
(40) Hagadorn, J . R.; Arnold, J . Inorg. Chem. 1997, 36, 2928.
(18) Brand, H.; Arnold, J . Coord. Chem. Rev. 1995, 140, 137.
(19) Giannini, L.; Solari, E.; De Angelis, S.; Ward, T. R.; Floriani,
C.; Chiesi-Villa, A.; Rizzoli, C. J . Am. Chem. Soc. 1995, 117, 5801.
(20) Scott, M. J .; Lippard, S. J . J . Am. Chem. Soc. 1997, 119, 3411.
(21) Hagadorn, J . R.; Arnold, J . Angew. Chem., Int. Ed. Engl., in
press.
(22) Hagadorn, J . R.; Arnold, J . Inorg. Chem. 1997, 36, 132.
(23) For reviews of transition-metal amidinates, see: Edelmann, F.
T. Coord. Chem. Rev. 1994, 137, 403. Dehnicke, K. Chem.-Ztg. 1990,
114, 295. Barker, J .; Kilner, M. Coord. Chem. Rev. 1994, 133, 219.

Titanium(II), -(III), and -(IV) Complexes
Organometallics, Vol. 17, No. 7, 1998 1357
structurally characterized by Roesky.24 We have found
that its synthesis is most conveniently carried out by
the addition of (TMEDA)LiL to TiCl4(THF)2 in THF, as
described by Gambarotta,34 followed by crystallization
from CH2Cl2. As shown in Scheme 1, the preparation
of Ti(IV) alkyl derivatives from L2TiCl2 is readily
accomplished by salt-metathesis reactions with Grig-
nard and dialkylmagnesium reagents. The monoalkyl
derivative L2Ti(Me)Cl was readily prepared by the slow
addition of 0.5 equiv of Me2Mg to a clear orange-red
benzene solution of L2TiCl2. Removal of volatile materi-
als from the red solution and crystallization from CH2-
Cl2 gave the product as dark red crystals in 72% yield.
When the reaction was carried out in Et2O with 1 equiv
of Me2Mg, complete conversion to L2TiMe2 occurred and
the product was crystallized from CH2Cl2 in 60% yield.
The dibenzyl derivative L2Ti(CH2Ph)2 was prepared by
the addition of PhCH2MgCl to a toluene solution of L2-
TiCl2 at -78 °C. The product was isolated as dark
purple crystals from Et2O in 44% yield. C6D6 solutions
of the dibenzyl are thermally sensitive, decomposing
within hours at 45 °C with the formation of toluene.
Compared to the dibenzyl, both methyl derivatives are
thermally stable in solution. Additionally, as solids,
they are stable for at least 1 year in a fluorescent-lit
F igu r e 1. ORTEP view of L2TiNCMe3 drawn with 30%
thermal ellipsoids. Atoms C(1B) and C(2B) of the disor-
dered tert-butyl group are omitted for clarity.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for L2TiNCMe3
Ti-N(1)
Ti-N(3)
Ti-N(5)
2.152(7)
2.156(8)
1.656(9)
Ti-N(2)
2.147(7)
2.148(8)
1.46(2)
Ti-N(4)
N(5)-C(1A)
N(1)-Ti-N(2)
N(1)-Ti-N(4)
N(2)-Ti-N(3)
N(2)-Ti-N(5)
N(3)-Ti-N(5)
Ti-N(5)-C(1A)
64.4(3)
N(1)-Ti-N(3)
N(1)-Ti-N(5)
N(2)-Ti-N(4)
N(3)-Ti-N(4)
N(4)-Ti-N(5)
155.3(3)
101.3(4)
64.0(3)
64.0(3)
114.2(4)
105.4(3)
103.5(3)
114.2(4)
103.4(4)
166(1)
1
N2-filled drybox. Variable-temperature H NMR spec-
troscopic data of L2TiMe2 shows a singlet for the -SiMe3
groups at temperatures down to -80 °C, indicative of
rapid rotation of the amidinate ligands at an uncon-
gested metal center. The methyl ligands are observed
as a singlet at 1.96 ppm, which is significantly downfield
of the related parameter of Cp2TiMe2 (-0.17 ppm).41
Comparable Sc and Zr compounds38,42,43 also display this
trend, which can be attributed to relatively electron-
deficient metal centers (L2TiMe2 is formally a 12-
electron complex).
The Ti-C bonds of L2TiMe2 were found to be reactive
toward a variety of protic reagents (water, alcohols,
amines) in C6D6. Refluxing 1 equiv of tert-butylamine
with the dimethyl in benzene followed by crystallization
from hexanes yielded red-orange crystals of L2TiNCMe3
in 44% yield (Scheme 1). 1H NMR spectroscopic data
indicated a ratio of two amidinate ligands per tert-butyl
group, and crystal structure analysis revealed the five-
coordinate terminal imido functionality.44 An ORTEP
view of the molecular structure is shown in Figure 1,
and bond lengths and angles are given in Table 1. The
chelating amidinate ligands are bound to Ti with
statistically identical Ti-N (average 2.151 Å) bond
lengths. The imido functionality displays a short (1.656-
(9) Å) Ti-N bond comparable to reported values for
(TMEDA)TiCl2NPh (1.702 Å),45 [(TMEDA)TiCl2NC-
(Me)]2 (1.699(4) Å),45 Cp*TiCl(Py)NBut (1.698(4) Å),46
and Ti(η4-Me8taa)(NBut) (1.724(4) Å) (taa ) tetraaza-
[14]annulene).47 The tert-butyl group is disordered over
two positions (see Experimental Section for details)
giving somewhat unreliable bond lengths and angles for
the imido ligand. What is certain is that the imido
ligand is bent, with a Ti-N-C angle of 166(1)°. This
suggests that the shortness of the bond is possibly due
to low steric crowding instead of a true Ti-N triple
bond.
Compared to related zirconocene imido derivatives,48
the Ti-imido linkage appears to be relatively inert. In
C6D6 solutions, no reaction was observed with ditolyl-
acetylene or H2 (2 atm) at 50 °C overnight. Reactivity
was observed, however, between L2TiNCMe3 and ac-
etone in C6D6 (eq 1). Complete conversion to L2Ti(µ-
O)2TiL[η1-NC(Ph)N(SiMe3)2] occurred within 2 h. The
dititanium bis(µ-oxo) product was independently pre-
pared by reaction of (L2Ti)2(µ-N2) with O2 (see later).
Red u ction Ch em istr y of L2TiCl2. As shown in
Scheme 2, the 1% Na/Hg amalgam reduction of L2TiCl2
in THF proceeded smoothly overnight giving paramag-
netic L2TiCl(THF), which was isolated as green crystals
from hexanes. Isolated yields were low (<30%) due to
the high solubility of the product and the floculent
nature of the crystalline solid. Solid-state magnetic-
susceptibility measurements (µeff ) 1.6 µB) are consis-
(41) Samuel, E.; Rausch, M. D. J . Am. Chem. Soc. 1973, 95, 6263.
(42) Hagadorn, J . R.; Arnold, J . Organometallics 1996, 15, 984.
(43) Hagadorn, J . R.; Arnold, J . J . Chem. Soc., Dalton Trans. 1997,
3087.
(44) Mountford, P. Chem. Commun. 1997, 2127.
(45) Duchateau, R.; Williams, A. J .; Gambarotta, S.; Chiang, M. Y.
Inorg. Chem. 1991, 30, 4863.
(46) Bai, Y.; Noltemeyer, M.; Roesky, H. W. Z. Naturforsch. 1991,
46b, 1357.
(47) Dunn, S. C.; Bastanov, A. S.; Mountford, P. J . Chem. Soc.,
Chem. Commun. 1994, 2007.
(48) Walsh, P. J .; Hollander, F. J .; Bergman, R. G. J . Am. Chem.
Soc. 1988, 110, 8729.

1358 Organometallics, Vol. 17, No. 7, 1998
Hagadorn and Arnold
Sch em e 2
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for L2TiCl
Ti-Cl
2.328(1)
2.071(3)
2.051(3)
1.749(3)
1.745(3)
1.352(4)
1.347(4)
Ti-N(1)
2.164(3)
2.119(3)
1.749(3)
1.756(3)
1.315(4)
1.328(4)
Ti-N(2)
Ti-N(3)
Ti-N(4)
Si(1)-N(1)
Si(3)-N(3)
N(1)-C(7)
N(3)-C(20)
Si(2)-N(2)
Si(4)-N(4)
N(2)-C(7)
N(4)-C(20)
Cl-Ti-N(1)
94.68(8)
95.77(8)
64.3(1)
115.0(1)
104.8(1)
137.2(2)
134.4(2)
Cl-Ti-N(2)
144.45(9)
110.25(9)
168.5(1)
104.2(1)
65.5(1)
Cl-Ti-N(3)
Cl-Ti-N(4)
N(1)-Ti-N(2)
N(1)-Ti-N(4)
N(2)-Ti-N(4)
Ti-N(1)-Si(1)
Ti-N(3)-Si(3)
N(1)-Ti-N(3)
N(2)-Ti-N(3)
N(3)-Ti-N(4)
Ti-N(2)-Si(2)
Ti-N(4)-Si(4)
138.5(2)
134.7(2)
F igu r e 2. ORTEP view of L2TiCl drawn with 50% thermal
ellipsoids.
slight elongation for Ti-N(1) and Ti-N(3) due to their
positions trans to each other. Other metrical values
associated with the benzamidinate ligands are unre-
markable.
Unlike the related Lewis-base-containing compound
L2Ti(µ-Cl)2Li(TMEDA),34 L2TiCl appears to be a good
starting material for the preparation of Ti(III) alkyls
by salt-metathesis methodology. Reaction of the chlo-
ride with LiCH2SiMe3 in toluene (eq 2) gave a dark red
solution, which upon hexanes workup and crystalliza-
tion from HMDSO yielded the Ti(III) alkyl L2TiCH2-
SiMe3 in 64% yield. The related methyl derivative was
tent with a Ti(III) metal center. Recrystallization from
hexanes resulted in the growth of red crystals inter-
mixed with L2TiCl(THF). This proved to be the related
base-free chloride, which was conveniently prepared by
the 1% Na/Hg reduction of L2TiCl2 in toluene. Follow-
ing hexanes workup, paramagnetic crystals of L2TiCl
were isolated in 57% yield. Although excess Na is used
in the overnight reaction, further reduction to Ti(II)
appears to be slow under these conditions (see later).
Combustion analysis and magnetic-susceptibility mea-
surements (µeff ) 1.6 µB) are consistent with the
expected base-free product. X-ray crystallography re-
vealed the base-free chloride to be monomeric with five-
coordinate titanium. An ORTEP view is shown in
Figure 2, with bond angles and lengths given in Table
2. The structure can be contrasted with that of the
related titanocene derivative (Cp2TiCl)2, which is dimer-
ic with bridging chloride ligands (average Ti-Cl, 2.543
Å).49 As expected, the Ti-Cl bond (2.328(1) Å) is slightly
longer than the related parameter of the Ti(IV) dichlo-
ride L2TiCl2 (2.257(3) Å).24 The Ti-N bonds show a
prepared by the 1% Na/Hg reduction of L2Ti(Me)Cl in
THF (eq 3). Removal of the volatile materials affords a
(49) J ungst, R.; Sekutowski, D.; Davis, J .; Luly, M.; Stucky, G. Inorg.
Chem. 1977, 16, 1645.
1
paramagnetic red solid that appears (by H NMR) to

Titanium(II), -(III), and -(IV) Complexes
Organometallics, Vol. 17, No. 7, 1998 1359
contain coordinated THF, but the base can be easily
removed by prolonged evacuation or successive addition/
evaporation of toluene to the solid followed by crystal-
lization from HMDSO. X-ray crystallographic data39 of
the methyl derivative revealed a monomeric five-
coordinate titanium with an apparent agostic interac-
tion between Ti and one of the methyl C-H bonds (Ti-
H, 2.51(5) Å; Ti-C-H, 104(3)°).
O) (Me3tacn ) 1,4,7-trimethyl-1,4,7-triazacyclononane)
which display only weakly antiferromagnetic coupling
(J ) 7 cm-1 average).52
Use of the chelating diamine TMEDA in an additional
attempt to trap the Ti(II) intermediate led to unprec-
edented reactivity and the formation of two products.
The 1% Na/Hg reduction of L2TiCl2 in the presence of
excess TMEDA in toluene occurred overnight, giving a
dark purple-brown solution. Following hexanes workup
and cooling to -40 °C, yellow crystals of L2TiNSiMe3
were isolated in 24% yield (Scheme 2). Characterization
Further reduction of L2TiCl2 with 1% Na/Hg to a Ti-
(II) species occurs over 2-3 days in toluene. When the
reaction was carried out under N2, this was observed
as a change in color from red to blue-black. After 3 days
of stirring, 1H NMR spectroscopic analysis of the crude
solution revealed the absence of any starting material
or L2TiCl and the presence of a single diamagnetic
product. After removal of volatile materials, extraction
into hexanes, and cooling to -40 °C, blue-black crystals
of the dinitrogen complex (L2Ti)2(µ-N2) were isolated in
moderate yield (41% from 3 crops). The X-ray crystal
structure39 revealed five-coordinate titanium and the
end-on bonding mode of the bridging N2. The compound
is thermally robust and failed to react with H2 (6 atm),
CO (2 atm), ethylene (1atm), PMe3, or ditolylacetylene
in C6D6, even after heating to 70 °C for several days.
Carrying out the 1% Na/Hg reduction of L2TiCl2 in
toluene under an atmosphere of CO gave a red-black
solution after 2 days. Hexanes workup of the solution
and cooling to -40 °C gave low yields of paramagnetic,
dark red crystals. Instead of the anticipated Ti(II)
dicarbonyl, the compound was determined by crystal-
lography to be (L2Ti)2(µ-O).39 Since carrying out the
reaction in the absence of CO (under argon) failed to
give this product, we felt it likely that the oxo ligand
was formed by the cleavage of CO. Additionally, it was
found to be highly reactive with O2, apparently yielding
multiple diamagnetic products in C6D6. To confirm the
CO bond cleavage, we carried out the reduction under
an atmosphere of C18O (eq 4). Electron-impact mass
1
by H NMR spectroscopy reveals two sharp singlets in
the -SiMe3 region with relative intensities of 36:9, and
its 13C{1H} NMR spectrum is very similar to that of L2-
TiNCMe3. Additionally, combustion analysis and EI-
MS data support its formulation. Further concentration
of the mother liquor and cooling yielded red-black
crystals of a second product LTi[η2-Me3SiNC(H)Ph][η3-
CH2N(Me)CH2CH2N(Me)2] in 42% yield. The solid-state
structure of the product was determined by X-ray
crystallography, revealing a seven-coordinate Ti bonded
to an amidinate ligand, an η2-imine, and a tridentate
cyclometalated TMEDA ligand.39 The long C-N(imine)
bond (1.446(8) Å) implies substantial metallaaziridine
character and formulation of the product as Ti(IV) as
opposed to Ti(II). The room-temperature 1H NMR
spectrum is complex, showing a multitude of broad
resonances, apparently due to hindered rotation and/
or the presence of diastereomers. On warming to 90
°C, however, the spectrum sharpens to give a pattern
consistent with the solid-state structure, with three
singlets for the inequivalent -SiMe3 groups and a
singlet for the imine hydrogen at 5.49 ppm. The
complexity of the room-temperature spectrum is inde-
pendent of concentration or the addition of TMEDA,
consistent with an intramolecular rearrangement.
Lew is-Ba se Ad d u ct s of (L2Ti)2(µ-N2). As stated
above, the bridging-dinitrogen complex (L2Ti)2(µ-N2) was
found to be unreactive toward a variety of σ-donor and
π-acceptor ligands. It was observed, however, that the
addition of a large excess of THF to a toluene solution
of the compound changed the color from dark blue to
green. Attempts to isolate a THF-containing product
by crystallization from THF/hexanes were unsuccessful,
and removal of the volatile materials afforded pure
starting material. By analogy to other Lewis-base
adducts mentioned below, we believe the green THF-
containing product to be [L2Ti(THF)]2(µ-N2) (eq 5). In
spectroscopy of this product confirmed CO as the sole
oxygen source for the µ-oxo ligand. Due to the low
isolated yields of the µ-oxo derivative, we presume that
additional products are formed during this reaction, but
to date we have been unable to isolate them and the
fate of the carbon atom remains to be determined.
Related reactions involving low-valent tantalum are
known to form oxo and dicarbide species,50 nonetheless,
in general, CO cleavage remains relatively rare.51 The
compound is paramagnetic (µeff ) 2.4 µB) with a mag-
netic moment that is consistent with two essentially
uncoupled d1-Ti centers. This value is similar to those
for (Me3tacn)2Ti2(NCO)4(µ-O) and (Me3tacn)2Ti2(NCS)4(µ-
contrast, addition of pyridine immediately gave a red
solution, which retained its color upon removal of
volatile materials under reduced pressure. Extraction
of the residue into hexanes and cooling to -30 °C yielded
dark red diamagnetic crystals in moderate yield. 1H
(50) LaPointe, R. E.; Wolczanski, P. T.; Mitchell, J . F. J . Am. Chem.
Soc. 1986, 108, 6382.
(51) For examples, see: Planalp, R. P.; Andersen, R. A.; Zalkin, A.
Organometallics 1983, 2, 16. Chisholm, M. H.; Hammond, C. E.;
J ohnston, V. J .; Streib, W. E.; Huffman, J . C. J . Am. Chem. Soc. 1992,
114, 7056. Arnold, J .; Tilley, T. D.; Rheingold, A. L.; Geib, S. J .; Arif,
A. M. J . Am. Chem. Soc. 1989, 111, 149-164 and references therein.
(52) J eske, P.; Wiegardt, K.; Nuber, B. Inorg. Chem. 1994, 33, 47.

1360 Organometallics, Vol. 17, No. 7, 1998
Hagadorn and Arnold
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [L2Ti(P y)]2(µ-N2)
Ti(1)-N(1)
Ti(1)-N(4)
Ti(1)-N(6)
Ti(2)-N(2)
Ti(2)-N(9)
Ti(2)-N(11)
N(1)-N(2)
1.799(4)
2.185(4)
2.111(4)
1.798(4)
2.251(4)
2.129(4)
1.264(5)
Ti(1)-N(3)
Ti(1)-N(5)
Ti(1)-N(7)
Ti(2)-N(8)
Ti(2)-N(10)
Ti(2)-N(12)
2.207(4)
2.337(4)
2.254(4)
2.156(4)
2.371(4)
2.233(4)
N(1)-Ti(1)-N(3)
N(1)-Ti(1)-N(5)
N(1)-Ti(1)-N(7)
N(3)-Ti(1)-N(5)
N(3)-Ti(1)-N(7)
N(4)-Ti(1)-N(6)
N(5)-Ti(1)-N(6)
N(2)-Ti(2)-N(8)
N(2)-Ti(2)-N(10)
N(2)-Ti(2)-N(12)
N(8)-Ti(2)-N(10)
N(8)-Ti(2)-N(12)
N(9)-Ti(2)-N(11)
N(10)-Ti(2)-N(11)
N(10)-Ti(2)-N(12)
Ti(1)-N(1)-N(2)
101.8(2) N(1)-Ti(1)-N(4)
161.2(2) N(1)-Ti(1)-N(6)
91.7(2) N(3)-Ti(1)-N(4)
95.3(1) N(3)-Ti(1)-N(6)
98.9(2) N(4)-Ti(1)-N(5)
101.8(1) N(4)-Ti(1)-N(7)
61.1(2) N(6)-Ti(1)-N(7)
102.7(2) N(2)-Ti(2)-N(9)
162.7(2) N(2)-Ti(2)-N(11)
90.3(2) N(8)-Ti(2)-N(9)
87.0(1) N(8)-Ti(2)-N(11)
154.5(1) N(9)-Ti(2)-N(10)
151.4(2) N(9)-Ti(2)-N(12)
60.3(1) N(10)-Ti(2)-N(11)
86.5(1) N(11)-Ti(2)-N(12)
173.0(3) Ti(2)-N(2)-N(1)
105.4(2)
103.6(2)
62.7(1)
153.1(2)
89.4(1)
77.8(1)
89.0(1)
104.0(2)
103.1(2)
62.0(1)
103.2(2)
93.2(1)
93.8(1)
60.3(1)
94.9(2)
174.4(3)
related metallocene derivative (Cp*2Ti)2(µ-N2)54 (1.165-
(14), 1.155(14) Å). This extreme reduction of the N2-
ligand correlates well with its relative nonlability
compared to metallocene derivatives (Cp*2Ti)2(µ-N2)55
and [Cp2Ti(PMe3)]2(µ-N2),56 which lose N2 at room
temperature. Analogous to the formation of the pyri-
dine adduct, addition of 2 equiv of XylylNC to (L2Ti)2-
(µ-N2) in toluene afforded the diamagnetic isocyanide
adduct [L2Ti(CNXylyl)]2(µ-N2), which was isolated as a
rose-colored floculent solid (50% yield) following hexanes
workup. Interestingly, the IR spectrum of this complex
shows a blue-shifted νCN at 2143 cm-1 compared to that
of free XylylNC (2115 cm-1). These data together with
the robust nature of the Ti2(µ-N2) core suggests sub-
stantial Ti(IV) character for the dinitrogen complexes.
Oxid a tion Rea ction s of (L2Ti)2(µ-N2). Several low-
valent group 4 metallocene derivatives have been suc-
cessfully used as precursors for the syntheses of com-
plexes containing metal-(group 16) bonds. Specific
examples include the oxidation of Cp*2Zr(CO)2 by
elemental sulfur in the presence of pyridine yielding the
Zr(IV) sulfido Cp*2Zr(S)Py57 and the formation of Cp*2-
Ti(O)Py from reaction of Cp*2Ti(C2H4) with N2O in THF/
pyridine.58 In exploring similar reactivity with (L2Ti)2-
(µ-N2), we found that it was readily oxidized by a variety
of oxygen and sulfur sources. The dinitrogen complex
reacted with dry oxygen in hexanes/pyridine (20:1),
immediately forming a clear orange solution. Removal
of volatile materials under reduced pressure afforded
an orange solid, which displayed NMR spectroscopic and
analytical data consistent with its formulation as the
peroxo derivative L2Ti(η2-O2)Py (Scheme 3). Due to
multiple bands in the region, we were unable to assign
the νO-O stretch in the infrared spectrum, however, the
seven-coordinate structure was confirmed by X-ray
crystallography.40
F igu r e 3. ORTEP view of [L2Ti(Py)]2(µ-N2) drawn with
50% thermal ellipsoids. Methyl groups are omitted for
clarity.
NMR data showed a pyridine-to-amidinate ratio of 1:2,
and IR spectroscopy revealed a stretch at 1602 cm-1
which is characteristic of coordinated Py. X-ray crystal-
lography confirmed the product to be [L2Ti(Py)]2(µ-N2)
(eq 6), with an intact Ti2N2 core. An ORTEP view is
shown in Figure 3, with bond distances and angles given
in Table 3. Shown in Figure 4 are a few other structur-
ally characterized complexes containing the Ti2(µ-N2)
core. Compared to the five-coordinate Ti centers of (L2-
Ti)2(µ-N2), the metal centers of the Py adduct are much
more crowded. This is reflected in increased Ti-N bond
lengths to the µ-N2 ligand (Ti(1)-N(1), 1.799(4) Å; Ti-
(2)-N(2), 1.798(4) Å). The µ-N2 ligand is highly reduced
in the diamagnetic complex, with a long N(1)-N(2) bond
of 1.264(5) Å that is slightly shorter than that of (L2-
Ti)2(µ-N2) (1.275(6) Å) and {[(Me3Si)2N]Ti(TMEDA)Cl}-
(µ-N2)53 (1.289(9) Å) but much longer than that of the
(54) Sanner, R. D.; Duggan, D. M.; McKenzie, T. C.; Marsh, R. E.;
Bercaw, J . E. J . Am. Chem. Soc. 1976, 98, 8358.
(55) Bercaw, J . E. J . Am. Chem. Soc. 1974, 96, 5087.
(56) Berry, D. H.; Procopio, L. J .; Carroll, P. J . Organometallics 1988,
7, 570.
(57) Howard, W. A.; Parkin, G. Organometallics 1993, 12, 2363.
(58) Smith, M. R.; Matsunaga, P. T.; Andersen, R. A. J . Am. Chem.
Soc. 1993, 115, 7049.
(53) Duchateau, R.; Gambarotta, S.; Beydoun, N.; Bensimon, C. J .
Am. Chem. Soc. 1991, 113, 8986.

Titanium(II), -(III), and -(IV) Complexes
Organometallics, Vol. 17, No. 7, 1998 1361
F igu r e 4. Comparison of the core structures of a few Ti2(µ-N2) complexes. See refs 39, 52, 53.
Sch em e 3
When the above reaction was repeated in the absence
of pyridine (in C6D6), a yellow-orange solution formed
immediately that displayed a complex H NMR spec-
At that temperature, 1H NMR spectroscopy revealed
only three signals in the -SiMe3 region, which is
consistent with the solid-state structure (assuming fast
ligand rotation).
1
trum with at least eight partially overlapping peaks in
the -SiMe3 region. Use of excess N2O in place of
oxygen, likewise, formed the same product. The reac-
tion was found to proceed cleanest, however, when
carried out with oxygen (1 atm) on powdered (L2Ti)2(µ-
N2). After exposure to oxygen for a few minutes a bright
yellow solid formed, which displayed spectroscopic data
(IR, NMR) identical to that of the product observed in
the solution reactions. Combustion data was consistent
with the empirical formula (L2TiO)n, and the solid-state
structure was determined to explain the nature of the
complex spectroscopic data. This revealed the product
to be L2Ti(µ-O)2TiL[η1-NC(Ph)N(SiMe3)2], which con-
tains an η1-iminoamine ligand formed by an unusual
silyl group migration at an amidinate ligand. The
bridging-oxo complex failed to react with several equiva-
lents of pyridine and is stable at 100 °C in toluene-d8.
Reaction of (L2Ti)2(µ-N2) with an excess of pyridine
N-oxide in toluene/pyridine (20:1) gave a lavender
solution after stirring overnight. Upon workup in Et2O
and cooling to -30 °C, crystals of the terminal oxo L2-
Ti(O)OPy were isolated in moderate yield. At 75 °C in
C6D6, the complex undergoes partial decomposition to
L2Ti(µ-O)2TiL[η1-NC(Ph)N(SiMe3)2] overnight, but the
reaction appears to be hindered by the Py-O released.
The structure of the complex was determined by X-ray
crystallography, and an ORTEP view is shown in Figure
5, with bond lengths and angles displayed in Table 4.
The complex features a pseudo-octahedral metal center.
The Ti-oxo bond (1.654(2) Å) is comparable to related
parameters of Cp*2Ti(O)(4-phenylpyridine) (1.665(3)
Å),58 (OEP)TiO (1.613(5) Å) (OEP ) octaethylporphy-
rin),59 and (2,6-iPr2-C6H4O)Ti(O)(NC5H4-4-NC4H8)2 (1.657-

1362 Organometallics, Vol. 17, No. 7, 1998
Hagadorn and Arnold
reflecting the size of the persulfido ligand. This is likely
responsible for the lack of reactivity that L2Ti(η2-S2)
displays toward pyridine.
The persulfido complex was found to react slowly with
metallic mercury in toluene. After the mixture was
stirred vigorously for 17 h, the initially teal solution
became red with a good amount of insoluble gray
precipitate, presumably HgS. Filtration and removal
of the volatile materials under reduced pressure af-
forded an orange solid that displayed a complex 1H
NMR spectrum similar to that described for L2Ti(µ-
O)2TiL[η1-NC(Ph)N(SiMe3)2], so it seemed likely that we
had prepared the sulfur-containing analogue. Addition-
ally, IR spectroscopic data revealed a strong absorbance
at 1518 cm-1, which we assign as νCdN of the η1-NC-
(Ph)N(SiMe3)2 ligand. Crystallization of the solid from
Et2O gave crystals that analyzed for the formula (L2-
TiS)n, and the X-ray structure confirmed that the
complex was indeed L2Ti(µ-S)2TiL[η1-NC(Ph)N(SiMe3)2].
An ORTEP diagram is shown in Figure 7, with metrical
parameters given in Table 6. Structurally, the complex
is very similar to the bridging-oxo analogue (Figure 8)
with a planar Ti2S2 core (torsion angle Ti(1)-S(1)-Ti-
(2)-S(2) ) 1.06(5)°) and alternating Ti-S bond lengths.
The Ti-S-Ti angles (average 89.7°) are relatively acute,
yet the Ti-Ti distance of 3.27 Å is considerably longer
than in the oxo derivative (2.75 Å). The η1-iminoamine
ligand, bound to the five-coordinate Ti, is bent with a
Ti-N-C angle of 158.0(3)° and a short Ti-N bond of
1.831(4) Å. The shortness of the bond suggests multiple
bond character,61 as a pure single bond is expected to
be about 1.96 Å. Additionally, the disilylamine group
appears to favor being coplanar with the N(7)-C(46)
double bond (torsion angles Si(7)-N(8)-C(46)-N(7),
19.0(5)°; Si(8)-N(8)-C(46)-N(7), 26.1(3)°), possibly re-
sulting in a delocalized Ti-N-C-N system.
F igu r e 5. ORTEP view of L2Ti(O)OPy drawn with 50%
thermal ellipsoids.
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for L2Ti(O)OP y
Ti-O(1)
1.654(2)
2.153(2)
2.394(3)
1.348(3)
1.335(4)
1.352(4)
Ti-O(2)
2.036(2)
2.173(3)
2.081(3)
1.331(4)
1.309(4)
Ti-N(1)
Ti-N(2)
Ti-N(3)
Ti-N(4)
N(1)-C(7)
N(3)-C(20)
O(2)-N(5)
N(2)-C(7)
N(4)-C(20)
O(1)-Ti-O(2)
O(1)-Ti-N(2)
O(1)-Ti-N(4)
O(2)-Ti-N(2)
O(2)-Ti-N(4)
N(1)-Ti-N(3)
N(2)-Ti-N(3)
N(3)-Ti-N(4)
98.5(1)
103.7(1)
97.4(1)
93.39(9)
95.45(9)
86.57(9)
99.02(9)
60.36(9)
O(1)-Ti-N(1)
O(1)-Ti-N(3)
O(2)-Ti-N(1)
O(2)-Ti-N(3)
N(1)-Ti-N(2)
N(1)-Ti-N(4)
N(2)-Ti-N(4)
Ti-O(2)-N(5)
103.1(1)
157.3(1)
151.05(9)
80.54(9)
63.1(1)
100.5(1)
155.7(1)
125.5(2)
(6) Å).60 The elongated Ti-N(3) bond length (2.394(3)
Å) compared to the other Ti-N bonds (average 2.136
Å) is attributed to the strong trans influence of the oxo
ligand. Comparison to the related sulfido derivative L2-
Ti(S)Py reveals very similar metrical trends but a less
pronounced trans influence (Figure 8). The amidinate
ligands are bonded in the typical bidentate manner with
the titanium sitting essentially in the NCN planes.
Excess sulfur was found to react with (L2Ti)2(µ-N2)
in toluene giving a teal solution within 1 h. The volatile
materials were stripped off, and the residue was crys-
tallized from hexanes yielding the persulfido derivative
L2Ti(η2-S2) in good yield. 1H NMR spectroscopic data
shows a sharp singlet for the -SiMe3 groups indicative
of a sterically uncongested metal center. The solid-state
structure was determined by X-ray crystallography.
Each asymmetric unit contains two independent mol-
ecules shown as ORTEP views in Figure 6, with bonds
and angles given in Table 5. The two molecules each
feature pseudo-octahedral titanium with nearly identi-
cal conformations. Titanium-sulfur bonds vary only
slightly in length, ranging from 2.308(2) to 2.317(2) Å.
The S-S bonds are statistically identical with values
of 2.074(2) and 2.075(2) Å. As shown in Figure 8, the
S-Ti-S angles (average 53.3°) are larger that the
related parameter of L2Ti(η2-O2)Py (O-Ti-O, 46.6°),
As shown in Scheme 3, the reaction of L2Ti(η2-S2) with
mercury in the presence of pyridine allowed for the
trapping of the terminal sulfido derivative L2Ti(S)Py.
Following hexanes workup, the product was isolated as
orange-red crystals from Et2O/hexanes in 23% yield.
Infrared spectroscopy showed an absorbance at 1601
cm-1, which is characteristic of coordinated pyridine,
1
and H NMR spectroscopic data (in C6D6) confirmed an
amidinate-to-pyridine ratio of 2:1. When several equiva-
lents of the base were added to a L2Ti(S)Py solution, a
single broadened signal was observed for the ortho-
pyridine protons, revealing rapid exchange. Heating a
C6D6 solution of the sulfido to 85 °C for 1 h resulted in
ca. 50% conversion to L2Ti(µ-S)2TiL[η1-NC(Ph)N(SiMe3)2].
Heating for an additional 12 h resulted in almost no
change, possibly due to the presence of free pyridine in
solution inhibiting further reaction. A dissociative
mechanism was supported by attempting the same
thermolysis in the presence of 9 equiv of free pyridine,
which resulted in almost no loss of the terminal sulfido
after heating for 1 h.
Su m m a r y a n d Con clu sion s
We have shown that the BTBA ligand is capable of
supporting a wide range of unusual titanium chemistry
(59) Guilard, R.; Latour, J .-M.; Lecomte, C.; Marchon, J .-C.; Protas,
J .; Ripoll, D. Inorg. Chem. 1978, 17, 1228.
(60) Hill, J . E.; Fanwick, P. E.; Rothwell, I. P. Inorg. Chem. 1989,
28, 3602.
(61) Giolando, D. M.; Kirschbaum, K.; Graves, L. J .; Bolle, U. Inorg.
Chem. 1992, 31, 3887.

Titanium(II), -(III), and -(IV) Complexes
Organometallics, Vol. 17, No. 7, 1998 1363
F igu r e 6. ORTEP view of two independent molecules of L2Ti(η2-S2) drawn with 50% thermal ellipsoids.
ane (HMDSO), N,N,N′,N′-tetramethylethylenediamine (TME-
DA), and pyridine (Py) were distilled from Na under argon.
Carbon monoxide was used directly from cylinders without
purification. 2,6-Dimethylphenyl isocyanide (XylylNC) was
purchased from Fluka and used as received. Elemental sulfur
and pyridine N-oxide (PyO) were purchased from Aldrich and
used as received. Oxygen was passed through a column of
Drierite prior to use. The compounds L2TiCl2,24,34 LiCH2-
SiMe3,62 and Me2Mg63,64 were prepared according to literature
procedures. PhCH2MgCl was prepared by the addition of
PhCH2Cl to a Mg suspension in Et2O. Melting points were
determined in sealed capillary tubes under nitrogen and are
uncorrected. 1H and 13C{1H} NMR spectra were recorded at
ambient temperatures unless stated otherwise. Chemical
shifts (δ) are given relative to residual protium in the deuter-
ated solvent at δ 7.15 and 7.24 for C6D6 and CDCl3, respec-
tively. IR samples were prepared as mineral oil mulls and
taken between KBr plates. Elemental analyses and mass
spectral data were determined within the College of Chemis-
try, University of California, Berkeley. Magnetic moments
were determined using a J ohnson-Mathey MSB-1 balance
unless stated otherwise. Single-crystal X-ray structure de-
terminations were performed at CHEXRAY, University of
California, Berkeley.
L2Ti(Me)Cl. Benzene (125 mL) was added to a 250-mL
round-bottomed flask containing L2TiCl2 (6.19 g, 9.58 mmol)
forming a clear orange solution. At 0 °C, an ethereal solution
of Me2Mg (15.5 mL, 4.79 mmol) was added dropwise, forming
F igu r e 7. ORTEP view of L2Ti(µ-S)2TiL[η1-NC(Ph)N-
(SiMe3)2] drawn with 50% thermal ellipsoids. Methyl
groups are omitted for clarity.
a
red solution. After addition, the mixture was stirred
in a variety of oxidation states. In several instances,
the L2Ti compounds show reactivity comparable to that
seen in related Cp2Ti derivatives but with some notable
differences; most of these may be attributed to the less
electron-rich nature of the BTBA series of compounds
relative to Cp systems. The unusual 1,3-silyl migration
chemistry to form η1-NC(Ph)N(SiMe3)2 species and the
C-N bond cleavage reactions to form imido complexes
reinforces the notion, well-documented in Cp chemistry,
that examples of completely “innocent” spectator ligands
are rare. Further reactivity studies of new complexes
will be presented in future publications.
overnight at room temperature. The volatile materials were
then removed under reduced pressure, and the red-pink solid
was extracted with CH2Cl2 (125 mL). Filtration through a
Celite pad on a fritted disk followed by concentration to 80
mL and cooling to -40 °C afforded dark red crystals of
analytically pure product (4.3 g, 72%). Mp: 191-194 °C. 1H
NMR (C6D6, 300 MHz): δ 7.30-7.25 (m, 4H), 7.02-6.98 (m,
6H), 2.26 (s, 3H), 0.18 (s, 36H). 13C{1H} NMR (C6D6, 75.5
MHz): δ 183.0, 139.8, 129.2, 126.3, 74.7, 2.3. IR: 1418 (s),
1247 (m), 1164 (w), 1076 (w), 1032 (w), 996 (m), 973 (m), 922
(w), 841 (s, br), 790 (m), 761 (m), 739 (m), 702 (m), 509 (m)
cm-1. Anal. Calcd for C27H49ClN4Si4Ti: C, 51.85; H, 7.90; N,
8.96. Found: C, 51.73; H, 7.73; N, 8.94.
L2TiMe2. To a clear orange solution of L2TiCl2 (3.00 g, 4.65
mmol) in diethyl ether (200 mL) was added a diethyl ether
solution of Me2Mg (16.0 mL, 4.65 mmol) dropwise over 40 min.
After the mixture was stirred overnight, the volatile materials
Exp er im en ta l Section
Gen er a l Con sid er a tion s. Standard Schlenk-line and
glovebox techniques were used. Tetrahydrofuran (THF), di-
ethyl ether, and hexanes were distilled from sodium/benzophe-
none under nitrogen. Dichloromethane and tert-butylamine
were distilled from CaH2 under nitrogen. C6D6 was vacuum
transferred from sodium/benzophenone. Hexamethyldisilox-
(62) Tessier-Youngs, C.; Beachley, O. T. Inorg. Synth. 1984, 24, 95.
(63) Coates, G. E.; Heslop, J . A. J . Chem. Soc. A 1968, 514.
(64) Andersen, R. A.; Wilkinson, G. J . Chem. Soc., Dalton Trans.
1977, 809.

1364 Organometallics, Vol. 17, No. 7, 1998
Hagadorn and Arnold
F igu r e 8. Comparison of the core structures.
Ta ble 5. Selected Bon d Dista n ces (Å) a n d An gles
Ta ble 6. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for L2Ti(η2-S2)
(d eg) for L2Ti(µ-S)2TiL[η1-NC(P h )N(SiMe3)2]
Ti(1)-S(1)
Ti(1)-S(2)
Ti(1)-N(1)
Ti(1)-N(2)
Ti(1)-N(3)
Ti(1)-N(4)
S(1)-S(2)
2.308(2)
2.310(2)
2.101(4)
2.093(4)
2.107(4)
2.092(4)
2.074(2)
Ti(2)-S(3)
Ti(2)-S(4)
Ti(2)-N(5)
Ti(2)-N(6)
Ti(2)-N(7)
Ti(2)-N(8)
S(3)-S(4)
2.317(2)
2.312(2)
2.111(4)
2.101(4)
2.100(4)
2.090(4)
2.075(2)
Ti(1)-S(1)
Ti(1)-N(1)
Ti(1)-N(3)
Ti(2)-S(1)
Ti(2)-N(5)
Ti(2)-N(7)
Si(8)-N(8)
N(2)-C(7)
N(4)-C(20)
N(6)-C(33)
N(8)-C(46)
2.310(1)
2.138(3)
2.183(3)
2.302(1)
2.170(3)
1.831(4)
1.794(4)
1.329(5)
1.332(5)
1.330(5)
1.367(5)
Ti(1)-S(2)
Ti(1)-N(2)
Ti(1)-N(4)
Ti(2)-S(2)
Ti(2)-N(6)
Si(7)-N(8)
N(1)-C(7)
N(3)-C(20)
N(5)-C(33)
N(7)-C(46)
2.284(1)
2.149(3)
2.135(3)
2.366(1)
2.094(3)
1.809(4)
1.337(5)
1.329(5)
1.335(5)
1.301(5)
S(1)-Ti(1)-S(2)
S(1)-Ti(1)-N(1)
S(1)-Ti(1)-N(2)
S(1)-Ti(1)-N(3)
S(1)-Ti(1)-N(4)
S(2)-Ti(1)-N(1)
S(2)-Ti(1)-N(2)
S(2)-Ti(1)-N(3)
S(2)-Ti(1)-N(4)
N(1)-Ti(1)-N(2)
N(1)-Ti(1)-N(3)
N(1)-Ti(1)-N(4)
N(2)-Ti(1)-N(3)
N(2)-Ti(1)-N(4)
N(3)-Ti(1)-N(4)
53.37(6)
102.3(1)
151.9(1)
99.7(1)
S(3)-Ti(2)-S(4)
S(3)-Ti(2)-N(5)
S(3)-Ti(2)-N(6)
S(3)-Ti(2)-N(7)
S(3)-Ti(2)-N(8)
S(4)-Ti(2)-N(5)
S(4)-Ti(2)-N(6)
S(4)-Ti(2)-N(7)
S(4)-Ti(2)-N(8)
N(5)-Ti(2)-N(6)
N(5)-Ti(2)-N(7)
N(5)-Ti(2)-N(8)
N(6)-Ti(2)-N(7)
N(6)-Ti(2)-N(8)
N(7)-Ti(2)-N(8)
53.25(5)
102.7(1)
156.3(1)
98.9(1)
99.6(1)
95.6(1)
S(1)-Ti(1)-S(2)
S(1)-Ti(1)-N(2)
S(1)-Ti(1)-N(4)
S(2)-Ti(1)-N(2)
S(2)-Ti(1)-N(4)
N(1)-Ti(1)-N(3)
N(2)-Ti(1)-N(3)
N(3)-Ti(1)-N(4)
S(1)-Ti(2)-N(5)
S(1)-Ti(2)-N(7)
S(2)-Ti(2)-N(6)
N(5)-Ti(2)-N(6)
N(6)-Ti(2)-N(7)
Ti(1)-S(2)-Ti(2)
Si(7)-N(8)-Si(8)
91.21(5) S(1)-Ti(1)-N(1)
92.8(1)
91.34(9)
103.7(1)
157.0(1)
63.3(1)
154.5(1)
96.9(1)
89.37(5)
141.5(1)
87.9(1)
100.6(1)
102.4(1)
102.0(1)
149.3(1)
65.2(1)
155.0(2)
99.5(1)
99.5(1)
100.3(1)
107.1(1)
100.3(1)
144.6(1)
64.9(1)
156.3(1)
103.0(1)
97.8(1)
155.7(1)
104.8(1)
98.0(1)
94.4(1)
99.0(1)
88.8(1)
62.9(1)
142.4(1)
105.1(1)
141.5(1)
63.8(1)
101.2(1)
S(1)-Ti(1)-N(3)
S(2)-Ti(1)-N(1)
S(2)-Ti(1)-N(3)
N(1)-Ti(1)-N(2)
N(1)-Ti(1)-N(4)
N(2)-Ti(1)-N(4)
S(1)-Ti(2)-S(2)
S(1)-Ti(2)-N(6)
S(2)-Ti(2)-N(5)
S(2)-Ti(2)-N(7)
N(5)-Ti(2)-N(7)
Ti(1)-S(1)-Ti(2)
107.1(2)
64.9(1)
106.8(1)
65.1(1)
113.4(1)
110.3(1)
90.18(5)
were removed under reduced pressure. The resulting red-
brown paste was extracted with CH2Cl2 (100 mL). Filtration
through a Celite pad on a fritted disk followed by concentration
to 40 mL and cooling to -40 °C gave the product as analytically
pure large red crystals (1.7 g, 60%). Mp: 151-155 °C. 1H
NMR (C6D6, 300 MHz): δ 7.30-7.25 (m, 4H), 7.05-7.00 (m,
6H), 1.96 (s, 6H), 0.15 (s, 36H). 13C{1H} NMR (C6D6, 75.5
MHz): δ 184.0, 140.7, 128.8, 128.3, 126.2, 69.1, 2.4. IR: 1427
(s), 1261 (m), 1247 (m), 1127 (w), 976 (s), 920 (w), 840 (s, br),
788 (m), 759 (m), 740 (m), 715 (m), 702 (m), 523 (m) cm-1. Anal.
Calcd for C28H52N4Si4Ti: C, 55.59; H, 8.66; N, 9.26. Found:
C, 55.57; H, 8.39; N, 9.38.
L2Ti(CH2P h )2. Toluene (100 mL) was added to L2TiCl2
(5.00 g, 7.74 mmol) forming an orange-red solution. After the
mixture was cooled to -78 °C, an Et2O solution of PhCH2MgCl
(9.86 mL, 15.5 mmol) was added dropwise over 5 min. The
flask was shielded from light and allowed to warm to ambient
temperature over a 5 h, forming a purple solution. After the
mixture was stirred for an additional 2 h, the volatile materials
were removed under reduced pressure. The dark solid was
89.22(5) Ti(2)-N(7)-C(46) 158.0(3)
122.0(2) Si(7)-N(8)-C(46) 113.9(3)
N(7)-C(46)-N(8) 123.4(4)
Si(8)-N(8)-C(46) 123.6(3)
extracted with Et2O (150 mL) and filtered. Cooling of the Et2O
extract to -30 °C afforded 1.38 g of product as dark purple
crystals. The dark solid, which did not extract into the Et2O,
was extracted with toluene (45 mL) and filtered. Cooling of
the toluene extract to -30 °C yielded 1.18 g of product as small,
dark purple crystals. Total yield: 44%. Mp: 126-127 °C. 1H
NMR (C6D6, 300 MHz): δ 7.45 (d, J ) 7.1 Hz, 4H), 7.31 (t, J
) 7.6 Hz, 4H), 7.2-6.9 (m, 12H), 3.90 (br, 2H), 3.09 (br, 2H),
0.02 (s, 36H). 13C{1H} NMR (C6D6, 75.5 MHz): δ 187.1, 154.0,
140.6, 129.1, 128.6, 128.3, 127.3, 121.9, 105.5, 3.9, 2.5. IR:
3064 (w), 1594 (m), 1450 (vs, br), 1247 (s), 1207 (m), 1157 (w),
1075 (w), 1029 (w), 995 (m), 975 (s), 920 (w), 840 (vs), 787 (m),
741 (m), 712 (m), 546 (w), 503 (m) cm-1
40H60N4Si4Ti: C, 63.45; H, 7.99; N, 7.40. Found: C, 63.34;
H, 8.04; N, 7.22.
. Anal. Calcd for
C

Titanium(II), -(III), and -(IV) Complexes
Organometallics, Vol. 17, No. 7, 1998 1365
L2TiNCMe3. To a 100-mL round-bottomed flask charged
with L2TiMe2 (2.25 g, 3.72 mmol) and benzene (50 mL) was
added tert-butylamine (0.41 mL, 3.9 mmol). The mixture was
heated to reflux overnight, then the volatiles were removed
under reduced pressure. The resulting red solid was extracted
with hexanes (50 mL) and filtered. Concentration to 25 mL
and cooling to -40 °C gave the product as large orange crystals
(1.04 g, 43.3%). Mp: 156-158 °C. 1H NMR (C6D6, 300
MHz): δ 7.38-7.33 (m, 4H), 7.07-7.03 (m, 6H), 1.33 (s, 9H),
0.20 (s, 36H). 13C{1H} NMR (C6D6, 75.5 MHz): δ 180.8, 141.2,
129.0, 128.2, 127.7, 70.8, 33.5, 3.2. IR: 1437 (s), 1408 (s), 1246
(s), 1208 (w), 1168 (w), 1211 (w), 1002 (sh), 987 (m), 922 (w),
THF. The residue was taken up in HMDSO and concentrated
to 20 mL. Cooling to -40 °C yielded red crystals (2.1 g, 69%)
of product. Recrystallization from HMDSO gave analytically
pure product. Mp: 120-122 °C. 1H NMR (C6D6, 300 MHz):
δ 10.93 (br, 4H), 8.48 (br, 4H), 7.77 (br, 2H), 1.21 (br, 36H).
IR: 1498 (m), 1448 (s, br), 1284 (s, br), 1258 (sh), 1245 (s),
1170 (w), 1094 (w), 1073 (w), 1032 (w), 1002 (sh), 982 (s), 917
(m), 844 (s, br), 785 (m), 758 (s), 718 (m), 701 (m), 682 (m),
604 (w), 533 (m), 505 (m) cm-1
. Anal. Calcd for C27H49N4-
OSi4Ti: C, 54.97; H, 8.37; N, 9.50. Found: C, 54.64; H, 8.55;
N, 9.27. µeff ) 1.6 µB.
(L2Ti)2(µ-N2). To a 500-mL round-bottomed flask contain-
ing L2TiCl2 (15.0 g, 23.3 mmol) and Na/Hg (4.45 g Na, 190
mmol) was added toluene (250 mL). After the mixture was
stirred for 3 days, a dark blue-black solution had formed. The
volatile materials were removed under reduced pressure. The
resulting black solid was extracted with warm toluene (150
mL) and filtered through Celite on a fritted disk. Concentra-
tion of the dark blue solution to 100 mL and cooling to -30 °C
gave the product as blue-black crystals. Total yield from 3
crops: 5.6 g, 41%. Mp: 268 °C (dec). 1H NMR (C6D6, 300
MHz): δ 7.56 (br, 4H), 7.15-7.08 (m, 6H), 0.22 (br, 36H). 13C-
{1H} NMR (C6D6, 75.5 MHz): δ 178.3, 141.6, 129.1, 127.7, 2.9
(br). IR: 1305 (w, br), 1259 (sh), 1246 (s), 1170 (w), 1074 (w),
1031 (w), 1002 (sh), 984 (s), 920 (w), 844 (s, br), 786 (w), 763
(m), 721 (w), 700 (w), 604 (w), 509 (m), 495 (sh) cm-1. Anal.
843 (s, br), 787 (w), 760 (m), 720 (w), 702 (w), 509 (m) cm-1
.
Anal. Calcd for C30H55N5Si4Ti: C, 55.78; H, 8.58; N, 10.84.
Found: C, 55.70; H, 8.61; N, 10.70.
L2TiCl(THF )‚0.5(p en ta n e). A 100-mL round-bottomed
flask was charged with L2TiCl2 (1.00 g, 1.55 mmol) and 1%
Na/Hg (0.071 g Na, 3.10 mmol). At -78 °C, tetrahydrofuran
(35 mL) was added and the solution was allowed to warm to
room temperature. After the mixture was stirred overnight,
the volatiles were removed under reduced pressure. The
resulting red-brown oil was extracted with pentane (50 mL)
and filtered. Concentration to 15 mL followed by cooling to
-40 °C gave the product as forest green flakes (0.30 g, 27%).
Mp: 107-108 °C. 1H NMR (C6D6, 300 MHz): δ 8.73 (br, 8H),
7.56 (br, 4H), 7.20 (br, 2H), 3.57 (br, 4H), 1.2 (m, 3H, pentane),
0.86 (t, 3H, pentane), 0.53 (br, 36H). IR: 1499 (w), 1245.3
(s), 1167 (w), 1074 (w), 1007 (m), 979 (s), 920 (w), 844 (s, br),
784 (w), 756 (m), 723 (w), 702 (w), 690 (w), 500 (m) cm-1. Anal.
Calcd for C32.5H60ClN4OSi4Ti: C, 54.33; H, 8.42; N, 7.80.
Found: C, 54.06; H, 8.66; N, 7.70. µeff ) 1.6 µB.
L2TiCl. A 100-mL round-bottomed flask was charged with
L2TiCl2 (2.00 g, 3.10 mmol) and 1% Na/Hg (0.142 g Na, 6.19
mmol). Toluene (45 mL), cooled to -78 °C, was added, and
the solution was allowed to warm slowly to room temperature.
After the mixture was stirred overnight, the volatiles were
removed under reduced pressure. The resulting red-gray
residue was extracted with pentane (100 mL) and filtered.
Concentration to 40 mL followed by cooling to -40 °C gave
the product as dark red crystals. Total yield from two crops:
1.1 g, 57%. Mp: 174-175 °C. 1H NMR (C6D6, 300 MHz): δ
10.42 (br, 4H), 8.49 (br, 4H), 7.63 (br, 2H), 1.28 (br, 36H). IR:
1600 (w), 1500 (m), 1247 (s), 1168 (w), 1074 (w), 1030 (w), 982
(s), 921 (w), 837 (s, br), 786 (m), 760 (s), 726 (m), 702 (m), 524
(m), 504 (sh) cm-1. Anal. Calcd for C26H46ClN4Si4Ti: C, 51.16;
H, 7.60; N, 9.18. Found: C, 50.83; H, 7.72; N, 9.06. µeff ) 1.6
µB.
L2TiCH2SiMe3. To a 100-mL round-bottomed flask charged
with (L2TiCl)2 (0.75 g, 0.61 mmol) and LiCH2SiMe3 (0.116 g,
1.22 mmol) was added toluene (20 mL), forming a clear dark
red solution. After the mixture was stirred overnight, the
volatile materials were removed under reduced pressure. The
resulting dark red residue was extracted with hexanes (40 mL)
and filtered. The hexanes were then removed under reduced
pressure and HMDSO (15 mL) was added. Concentration to
3 mL and cooling to -40 °C gave the product as red crystals
(0.52 g, 64%). Mp: 110-112 °C. 1H NMR (C6D6, 300 MHz):
δ 10.82 (br, 4H), 8.36 (br, 4H), 7.77 (br, 2H), 0.95 (br, 36H),
0.10 (br, 9H). IR: 1260 (sh), 1247 (s), 1168 (w), 1073 (w), 983
(s), 917 (w), 844 (s, br), 785 (w), 759 (m), 721 (w), 701 (m), 604
(w), 518 (m) cm-1. Anal. Calcd for C30H57N4Si5Ti: C, 54.42;
H, 8.68; N, 8.46. Found: C, 54.09; H, 8.63; N, 8.48. µeff ) 1.6
µB.
L2TiMe. Tetrahydrofuran (40 mL) was added to L2Ti(Me)-
Cl (3.25 g, 5.20 mmol) and Na/Hg (0.48 g Na, 20.8 mmol) in a
100-mL round-bottomed flask. After the mixture was stirred
overnight, the volatile materials were removed under reduced
pressure. The red-brown solid was extracted with hexanes (80
mL) and filtered through a Celite pad on a fritted disk. The
volatiles were removed under reduced pressure, and the
residue was evacuated overnight to remove any remaining
Calcd for
C52H92N10Si8Ti2: C, 53.03; H, 7.87; N, 11.89.
Found: C, 52.74; H, 7.85; N, 11.91.
(L2Ti)2(µ-O). Manipulations were carried out under argon.
Toluene (100 mL) was added to a 250-mL round-bottomed flask
containing L2TiCl2 (2.00 g, 3.10 mmol) and Na/Hg (0.71 g Na,
31 mmol). The flask was briefly evacuated and then backfilled
with CO. After the mixture was stirred for 2 days, the volatile
materials were removed under reduced pressure. The result-
ing black solid was extracted with hexanes (100 mL) and
filtered through a pad of Celite on a fritted disk. Concentra-
tion to 30 mL and cooling to -40 °C gave the product as red-
black crystals (0.38 g, 18%). Mp: 275 °C (dec). 1H NMR (C6D6,
300 MHz): δ 10.0 (v br), 7.58 (br, 4H), 6.65 (br, 2H), 2.0-0.2
(50H). IR: 1407 (s), 1259 (sh), 1248 (s), 1172 (w), 982 (s), 918
(w), 848 (s, br), 791 (s), 761 (s), 721 (m), 700 (m), 605 (w), 510
(m) cm-1. Anal. Calcd for C64H120N8OSi8Ti2: C, 53.57; H, 7.95;
N, 9.61. Found: C, 53.20; H, 8.16; N, 9.51. µeff ) 2.4 µB. EI-
MS 1165 (M+) (correct isotope pattern was observed).
(L2Ti)2(µ-18O). The above reaction was carried out on a one-
half scale using C18O (95% 18O). Mp: 275 °C (dec). EI-MS
1167 (M+) (correct isotope pattern for the 18O incorporated
product was observed).
Red u ction of L2TiCl2 in th e P r esen ce of TMEDA. All
manipulations were carried out under Ar. Toluene (40 mL)
and TMEDA (2.3 mL, 16 mmol) were added to a 100-mL round-
bottomed flask containing L2TiCl2 (1.00 g, 1.55 mmol) and Na/
Hg (0.21 g Na, 9.2 mmol). After the mixture was stirred
overnight, the volatiles were removed under reduced pressure.
The purple-brown residue was extracted with hexanes (40 mL)
and filtered through a Celite pad on a fritted disk. Concentra-
tion to 3 mL and cooling to -40 °C yielded yellow crystals (0.25
g, 24% based on Ti) of L2TiNSiMe3. Concentration of the
mother liquor to 2 mL and cooling to -40 °C yielded red-black
crystals (0.39 g, 42% based on Ti) of LTi[η2-Me3SiNC(H)Ph]-
[η3-CH2N(Me)CH2CH2N(Me)2]. Recrystallization of both prod-
ucts from hexanes yielded analytically pure samples.
L2TiNSiMe3: Mp 162-163 °C; 1H NMR (C6D6, 300 MHz) δ
7.37-7.31 (m, 4H), 7.05-6.98 (m, 6H), 0.29 (s, 9H), 0.20 (s,
36H); 13C{1H} NMR (C6D6, 75.5 MHz) δ 181.8, 140.6, 129.4,
128.2, 3.8, 2.9; MS (EI) m/z (relative intensity) 661 (M+, 87),
572 (20), 558 (10), 543 (20), 399 (53), 304 (10), 280 (10), 263
(12), 247 (10), 176 (57), 73 (100); IR 1425 (s, br), 1245 (s), 1166
(w), 1111 (s), 1074 (sh), 1030 (m), 1002 (m), 986 (s), 926 (w),
842 (s, br), 789 (m), 757 (s), 701 (m), 637 (w), 603 (w), 511 (m)
cm-1
. Anal. Calcd for C29H55N5Si5Ti: C, 52.61; H, 8.37; N,

1366 Organometallics, Vol. 17, No. 7, 1998
Hagadorn and Arnold
10.58. Found: C, 52.41; H, 8.43; N, 10.40. LTi[η2-Me3SiNC-
C52H92N8O2Si8Ti2: C, 52.85; H, 7.85; N, 9.48. Found: C, 52.39;
H, 7.84; N, 9.26.
1
(H)P h ][η3-CH2N(Me)CH2CH2N(Me)2]: Mp 101-103 °C; H
NMR (C6D6, 300 MHz, 90 °C): δ 7.43-7.38 (m, 2H), 7.30-
7.24 (m, 2H), 7.13 (m, 1H), 7.08-7.01 (m, 3H), 6.94-6.85 (m,
1H), 5.49 (s, 1H), 3.09 (br, 2H), 2.74 (br, 3H), 2.61-2.55 (m,
2H), 2.36 (br, 2H), 2.13 (s, 6H), 0.29 (s, 9H), -0.03 (s, 9H),
-0.29 (s, 9H); 13C{1H} NMR (C6D6, 75.5 MHz, 80 °C) δ 155.1,
140.5, 128.7, 128.1, 126.9, 122.4, 121.1, 111.8, 58.0, 56.1, 46.9,
45.8, 2.3, 2.0; IR 1587 (s), 1432 (s, br), 1377 (m), 1277 (w), 1244
(s), 1219 (m), 1169 (w), 1148 (w), 1126 (m), 1070 (m), 984 (s),
940 (w), 910 (w), 836 (s, br), 785 (w), 757 (m), 744 (m), 708
(m), 675 (w), 640 (w), 609 (w), 558 (w), 536 (m), 505 (m), 482
(m) cm-1. Anal. Calcd for C29H53N5Si3Ti: C, 57.68; H, 8.85;
N, 11.60. Found: C, 57.81; H, 9.05; N, 11.48.
L2Ti(O)OP y. Hexanes (20 mL) and pyridine (1 mL) were
added to (L2Ti)2(µ-N2) (0.26 g, 0.22 mmol) forming a dark red
solution. This solution was added to solid PyO (0.10 g, 1.1
mmol) in a 100-mL round-bottomed flask. Toluene (20 mL)
was added to help dissolve the PyO. After the mixture was
overnight, the volatile materials were removed under reduced
pressure, affording a rose solid. The solid was extracted with
Et2O (30 mL) and filtered. Concentration to 20 mL and cooling
to -30 °C afforded the product as pale lavender crystals (0.11
g, 37%). Recrystallization from Et2O gave analytically pure
colorless crystals. Mp: 167-169 °C (dec). 1H NMR (C6D6, 300
MHz): δ 9.29 (br, 2H), 7.40 (m, 4H), 7.15-7.05 (m, 6H), 6.29
(t, 1H), 6.22 (t, 2H), 0.25 (s, 36H). IR: 1529 (s), 1460 (vs, br),
1435 (s), 1378 (s), 1242 (s), 1217 (s), 1167 (m), 1071 (w), 1010
(w), 981 (s), 929 (m), 909 (s), 841 (vs, br), 789 (m), 759 (s), 722
(m), 701 (m), 673 (w), 605 (w), 578 (m), 500 (m) cm-1. Anal.
[L2Ti(P y)]2(µ-N2). Pyridine (74 µL, 0.91 mmol) was added
to a dark blue solution of (L2Ti)2(µ-N2) (0.27 g, 0.23 mmol) in
toluene (20 mL). Immediately, a deep red solution formed.
After the mixture was stirred overnight, the volatile materials
were removed under reduced pressure, affording a red solid.
The solid was extracted with hot hexanes (50 mL) and filtered.
Cooling to -30 °C gave the product as red blocks. Total yield
from 2 crops: 0.132 g, 43.3%. Mp: 142 °C (dec). 1H NMR
(C6D6, 300 MHz, 60 °C): δ 9.10 (v br, 4H), 7.43 (br, 8H), 7.15-
6.90 (m), 0.20 (s, 72H). IR: 1602 (w), 1498 (m), 1460 (br, vs),
1376 (s), 1244 (m), 1166 (w), 1071 (w), 981 (s), 922 (w), 842
(br, s), 784 (w), 757 (m), 702 (m), 494 (m) cm-1. Anal. Calcd
for C62H102N12Si8Ti2: C, 55.74; H, 7.69; N, 12.58. Found: C,
56.05; H, 7.83; N, 12.42.
Calcd for
C31H51N5O2Si4Ti: C, 54.28; H, 7.49; N, 10.21.
Found: C, 54.22; H, 7.55; N, 10.11.
L2Ti(η2-S2). Toluene (25 mL) was added to (L2Ti)2(µ-N2)
(0.21 g, 0.18 mmol) and S8 (79 mg, 0.31 mmol) forming a dark
blue solution. Within a few minutes, the solution became teal.
After 45 min, the volatiles were removed under reduced
pressure giving a teal solid. The solid was extracted with
hexanes (35 mL). A small amount of pale solid was filtered
off, likely unreacted sulfur. Upon concentration, more pale
solid formed. The solution was then filtered again, concen-
trated to 10 mL, and cooled to -30 °C. The product was
isolated as green-black blocks (0.14 g, 62%). An analytically
pure sample was obtained by recrystallization from hexanes.
Mp: 178-180 °C. 1H NMR (C6D6, 300 MHz): δ 7.22-7.19 (m,
4H), 7.00-6.90 (m, 6H), 0.11 (s, 36H). IR: 1456 (vs, br), 1417
(s), 1399 (s), 1376 (s), 1258 (m), 1243 (s), 1163 (m, br), 1074
(w), 1031 (w), 1004 (m), 978 (s), 922 (w), 844 (vs, br), 784 (w),
763 (s), 745 (w), 707 (s), 668 (w), 522 (m), 513 (m) cm-1. Anal.
Calcd for C26H46N4S2Si4Ti: C, 48.87; H, 7.26; N, 8.77. Found:
C, 49.02; H, 7.34; N, 8.66.
[L2Ti(CNXylyl)]2(µ-N2). Toluene (15 mL) was added to (L2-
Ti)2(µ-N2) (0.26 g, 0.22 mmol) and XylylNC (57 mg, 0.43 mmol)
forming a dark red solution. After 30 min, the volatile
materials were removed under reduced pressure, affording a
dark red solid. The solid was extracted with warm hexanes
(30 mL) and filtered. Concentration to 20 mL and cooling to
-30 °C gave the product as a rose solid (0.16 g, 50%). Mp:
137 °C (dec). 1H NMR (C6D6, 300 MHz, 50 °C): δ 7.57 (m,
8H), 7.19-7.08 (m), 6.68 (br, 6H), 2.36 (br, 12H), 0.25 (s, 72H).
IR: 2143 (s), 1510 (m), 1454 (br, vs), 1371 (s), 1360 (s), 1241
(m), 1169 (w), 1001 (w), 978 (s), 913 (w), 843 (br, s), 776 (m),
L2Ti(µ-S)2TiL[η1-NC(P h )N(SiMe3)2]. Toluene (20 mL)
was added to L2Ti(η2-S2) (0.20 g, 0.31 mmol) and Hg (11 g) in
a 100-mL round-bottomed flask, forming a teal solution. After
the mixture was stirred for 17 h, the solution became red. The
volatile materials were removed under reduced pressure. The
solid was extracted with hexanes (35 mL) and filtered through
Supercel on a fritted disk. The clear, orange-red solution was
stripped to dryness, affording an orange solid (0.10 g, 53%).
Crystallization from Et2O yielded analytically pure product
in ca. 20% yield. Mp: 228-230 °C. 1H NMR (CDCl3, 300
MHz): δ 8.17-8.12 (m, 2H), 7.41-7.25 (m, 18H), 0.25 (s, 18H),
0.24 (s, 9H), -0.08 (br, 18H), -0.16 (s, 9H), -0.30 (v br, 18H).
IR: 1518 (s), 1459 (vs, br), 1377 (s), 1294 (m), 1281 (m), 1257
(w), 1243 (m), 1168 (w), 1143 (w), 1073 (w), 1030 (w), 1002
(m), 988 (m), 976 (m), 920 (w), 843 (s, br), 767 (m), 722 (m),
655 (w), 501 (m), 488 (w) cm-1. Anal. Calcd for C52H92N8S2-
Si8Ti2: C, 51.45; H, 7.64; N, 9.23. Found: C, 51.36; H, 7.75;
N, 9.21.
L2Ti(S)P y. Mercury (15 g) was added to a dark green
solution of L2Ti(η2-S2) (0.32 g, 0.50 mmol), pyridine (0.40 g,
4.9 mmol), and toluene (25 mL). After the mixture was stirred
overnight, the solution became orange-red. The volatile
materials were removed under reduced pressure, and the solid
was extracted with hexanes (40 mL). The solution was filtered
through Supercel on a fritted disk, and the hexanes were
removed under reduced pressure. Crystallization form Et2O/
hexanes at -30 °C yielded the product as small orange-red
crystals (80 mg, 23%). Mp: 221-227 °C. 1H NMR (C6D6, 300
MHz): δ 9.53 (br, 2H), 7.36 (m, 4H), 7.10-7.00 (m, 6H), 6.95
(br, 1H), 6.67 (br, 2H), 0.20 (s, 36H). IR: 1601 (m), 1499 (m),
1463 (vs, br), 1426 (s), 1379 (s), 1246 (s), 1215 (w), 1167 (w),
1068 (w), 1002 (w), 992 (w), 977 (s), 842 (s, br), 791 (w), 760
(m), 722 (m), 699 (w), 631 (w), 520 (m), 501 (m) cm-1. Anal.
755 (m), 722 (w), 698 (w) cm-1
70H110N12Si8Ti2‚hexane: C, 59.80; H, 8.19; N, 11.01. Found:
C, 60.01; H, 8.24; N, 10.97.
.
Anal. Calcd for
C
L2Ti(η2-O2)P y. Pyridine (1 mL) was added to a hexanes
solution (20 mL) of (L2Ti)2(µ-N2) (0.35 g, 0.30 mmol) forming
a dark red solution. The flask was evacuated briefly and then
backfilled with dry O2 (2 psig). Within 20 s, a clear orange
solution had formed. After 2 min, the volatile materials were
removed under reduced pressure, giving an orange solid (0.28
g, 69%). The product can be crystallized from Et2O in ca. 40%
yield. Mp: 128-132 °C. 1H NMR (C6D6, 300 MHz): δ 9.17
(d, 2H), 7.24 (m, 4H), 7.01 (m, 6H), 6.93 (t, 1H), 6.61 (t, 2H),
0.12 (s, 36H). IR: 1601 (m), 1501 (m), 1461 (vs, br), 1384 (s,
br), 1244 (s), 1216 (w), 1168 (w), 1151 (w), 1073 (w), 1040 (w),
1008 (w), 981 (s), 887 (s), 842 (s, br), 792 (m), 758 (m), 743
(m), 720 (m), 701 (m), 633 (w), 613 (m), 573 (m), 500 (m) cm-1
.
Anal. Calcd for C31H51N5O2Si4Ti: C, 54.28; H, 7.49; N, 10.21.
Found: C, 54.59; H, 7.60; N, 10.11.
L2Ti(µ-O)2TiL[η1-NC(P h )N(SiMe3)2]. A sample of (L2Ti)2-
(µ-N2) (0.19 g, 0.16 mmol) was ground to a powder using a
mortar and pestle. This blue powder was loaded into a
Schlenk tube and evacuated. Upon filling the tube with dry
1
O2 (2 psig), the solid became a bright yellow. After 5 min, H
NMR spectroscopy of the sample (in C6D6) revealed it to be
completely converted to the product (0.15 g, 79%). Mp: 225-
229 °C. 1H NMR (toluene-d8, 300 MHz, 100 °C): δ 8.09 (d,
2H), 7.5-6.9 (m), 0.34 (s), 0.19 (br), 0.19 (s), 0.00 (br) (total 72
H for -SiMe3 region). IR: 1575 (w), 1546 (s), 1499 (m), 1460
(vs, br), 1374 (s), 1243 (s, br), 1173 (w, br), 1122 (w), 1074 (w),
981 (m), 917 (w), 843 (vs, br), 765 (m), 722 (m), 677 (m), 651
(m), 613 (m), 595 (m), 504 (m), 487 (m) cm-1. Anal. Calcd for

Titanium(II), -(III), and -(IV) Complexes
Organometallics, Vol. 17, No. 7, 1998 1367
Ta ble 7. Cr ysta l Da ta a n d Collection P a r a m eter s (L ) P h C(NSiMe3)2)
L2TiNCMe3 L2TiCl [L2Ti(Py)]2(µ-N2) L2Ti(O)OPy
L2Ti(η2-S2)
compd
L2Ti(µ-S)2TiL[η1-
NC(Ph)N(SiMe3)2]
formula
fw
C
30H55N5Si4Ti
C26H46N4Si4TiCl C62H102N12Si8Ti2 C31H51N5Si4TiO2 C26H46N4Si4TiS2 C52H92N8Si8Ti2S2
689.36
610.37
1336.05
686.02
639.04
1213.96
space group
temp (°C)
a (Å)
P21/n (No. 14)
-105
11.438(3)
29.93(1)
11.530(4)
3847(2)
P1h (No. 2)
Cc (No. 9)
-135
18.4660(4)
14.3878(2)
29.4826(6)
7529.0(4)
P21/c (No. 14)
-99
15.7453(1)
11.5487(1)
21.7934(2)
3824.47(5)
P21/n (No. 14)
-114
20.0421(4)
15.7823(2)
24.1409(5)
7109.1(3)
P1h (No. 2)
-142
-93
12.1926(4)
12.7951(3)
13.1292(5)
1708.1(2)
66.031(1)
74.957(1)
66.799(1)
2
12.9999(2)
14.076(2)
20.9523(1)
3446.2(1)
105.438(1)
104.062(1)
100.199(1)
2
b (Å)
c (Å)
V (Å3)
R (deg)
â (deg)
γ (deg)
Z
102.93(2)
106.019(1)
105.186(1)
111.409(1)
4
4
4
8
d
calc (g/cm3)
1.116
1.187
1.179
1.191
1.194
1.170
diffractometer
Enraf-Nonius
CAD-4
Siemens
SMART
Mo KR (λ )
0.710 73 Å)
graphite
Siemens
SMART
Mo KR (λ )
0.710 73 Å)
graphite
CCD area
detector
ω, 0.3°
Siemens
SMART
Mo KR (λ )
0.710 73 Å)
graphite
CCD area
detector
ω, 0.3°
Siemens
SMART
Mo KR (λ )
0.710 73 Å)
graphite
CCD area
detector
ω, 0.3°
Siemens
SMART
Mo KR (λ )
0.710 73 Å)
graphite
CCD area
detector
ω, 0.3°
radiation
Mo KR (λ )
0.710 73 Å)
monochromator graphite
detector
crystal scintillation CCD area
counter
θ-2θ, ∆θ ) 0.70
+ 0.35 tan θ
5.49 (θ, deg/min)
-h,-k,(l
detector
ω, 0.3°
scan type,
width
scan speed
reflections
measured
2θ range (deg)
30 s/frame
hemisphere
30 s/frame
hemisphere
10 s/frame
hemisphere
10 s/frame
hemisphere
20 s/frame
hemisphere
3-45
0.372
0.86, 1.00
0.70 × 0.60 ×
0.40
3-46.5
0.490
0.825, 0.985
0.17 × 0.11 ×
0.07
3-46.5
0.383
0.848, 0.917
0.15 × 0.13 ×
0.04
3-46.5
0.382
0.771, 0.942
0.40 × 0.23 ×
0.21
3-46.5
0.514
0.763, 0.966
0.39 × 0.14 ×
0.12
3-46.5
0.469
0.797, 0.977
0.41 × 0.07 ×
0.07
µ (mm-1
)
T
min, Tmax
cryst dimens
(mm)
no. of reflns
measd
5759
8198
15 878
15 692
29 535
14 503
no. of unique
reflns
no. of
5298
3618
5725
3946
7706
6086
5767
3737
10 577
5066
9671
6127
observations
no. of params
R, Rw (%)
GOF
359
11.3, 12.8
5.850
325
4.11, 4.82
1.426
755
3.45, 4.00
1.293
388
3.51, 4.16
1.426
667
3.69, 3.94
1.142
649
4.20, 4.56
1.331
Calcd for C31H51N5SSi4Ti: C, 54.27; H, 7.49; N, 10.21.
Found: C, 54.26; H, 7.57; N, 10.11.
X-r a y Cr ysta llogr a p h y. Table 7 lists a summary of crystal
data and collection parameters for all structurally character-
ized compounds. Specific details of individual data collection
and solution are given below.
left 5298 unique reflections in the final data set. The structure
was solved and refined with the teXsan67 software package
using direct methods68 and expanded using Fourier tech-
niques.69 Disorder in the tert-butyl group was modeled as one-
half occupancy in two positions, leading to four one-half-
occupancy carbon atoms (C(1A), C(1B), C(2A), C(2B)), which
were refined isotropically. All remaining non-hydrogen atoms
were refined anisotropically. Hydrogen atoms were assigned
idealized positions (not included for tert-butyl group) and were
included in structure factor calculations but were not refined.
The p-factor, used to reduce the weight of intense reflections,
was set to 0.030 throughout the refinement. The analytical
forms of the scattering factor tables for the neutral atoms were
used,70 and all scattering factors were corrected for both the
real and imaginary components of anomalous dispersion.71
L2TiCl. Crystals suitable for X-ray diffraction studies were
grown over several days at -30 °C from hexanes solution. A
L2TiNCMe3. Crystals suitable for X-ray diffraction studies
were grown from hexanes at -20 °C. A large crystal was cut
to the appropriate size (0.70 × 0.60 × 0.40 mm) and mounted65
on a glass fiber using Paratone-N hydrocarbon oil. The crystal
was transferred to an Enraf-Nonius CAD-4 diffractometer,
centered in the beam, and cooled to -105 °C by a nitrogen-
flow low-temperature apparatus, which had been previously
calibrated by a thermocouple placed at the same position as
the crystal. Automatic peak search and indexing procedures
yielded a primitive monoclinic cell.
The 5694 raw intensity data were converted to structure
factor amplitudes and their esd’s by correction for scan speed,
background, and Lorentz and polarization effects. Inspection
of intensity standards revealed an overall decay of 36%. The
data were corrected for this decay. Inspection of the azimuthal
scan data66 showed a variation Imin/Imax ) 0.86 for the average
curve. An empirical correction was applied to the data using
DIFABS. Inspection of the systematic absences uniquely
indicated space group P21/n (No. 14). Removal of the system-
atically absent and averaging of redundant data (Rint ) 16.8%)
(67) teXsan: Crystal Structure Analysis Package; Molecular Struc-
ture Corp.: The Woodlands, TX, 1992.
(68) Hai-Fu, F. Structure Analysis Programs with Intelligent Control;
Hai-Fu, F., Ed.; Rigaku Corp.: Tokyo, 1991.
(69) Beurskens, P. T.; Admiraal, G.; Beuskens, G.; Bosman, W. P.;
Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smkalla, C.
DIRDIF92: The DIRDIF Program System; Technical Report of the
Crystallography Laboratory; Beurskens, P. T., Admiraal, G., Beuskens,
G., Bosman, W. P., Garcia-Granda, S., Gould, R. O., Smits, J . M. M.,
Smkalla, C., Eds.; University of Nijmegen: Nijmegen, The Nether-
lands, 1992.
(65) Hope, H. Experimental Organometallic Chemistry; Wayda, A.
L., Darensbourg, M. Y., Eds.; American Chemical Society, Conference
Proceedings; Washington, DC, 1987; Vol. 357, p 257.
(66) Reflections used for azimuthal scans were located near ø ) 90°,
and the intensities were measured at 10° increments of rotation of
the crystal about the diffraction vector.
(70) Cromer, D. T.; Waber, J . T. In International Tables for X-ray
Crystallography; The Kynoch Press: Birmingham, England, 1974; Vol.
IV, Table 2.2B.
(71) Cromer, D. T.; Waber, J . T. In International Tables for X-ray
Crystallography; The Kynoch Press: Birmingham, England, 1974; Vol.
IV, Table 2.3.1.

1368 Organometallics, Vol. 17, No. 7, 1998
Hagadorn and Arnold
large crystal was cut to the appropriate size (0.17 × 0.11 ×
0.07 mm) and mounted as above. The crystal was transferred
to a Siemens SMART diffractometer/CCD area detector,72
centered in the beam, and cooled to -142 °C by a nitrogen
flow low-temperature apparatus, which had been previously
calibrated by a thermocouple placed at the same position as
the crystal. Preliminary orientation matrix and cell constants
were determined by collection of 60 10-s frames, followed by
spot integration and least-squares refinement. A hemisphere
of data was collected using 0.3° ω scans at 30 s per frame.
The raw data were integrated (xy spot spread ) 1.60°; z spot
spread ) 0.60°) and the unit cell parameters refined (4311
reflections with I >10σ(I)) using SAINT.73 Data analysis was
performed using XPREP.74 Absorption correction was applied
using SADABS (Tmin ) 0.825, Tmax ) 0.985).75 The unit cell
parameters indicated a triclinic cell. The choice of the centric
space group was confirmed by the successful refinement of the
model. The data were corrected for Lorentz and polarization
effects, but no correction for crystal decay was applied.
The 8198 reflections measured were averaged (Rint ) 2.45%),
yielding 7706 unique reflections. The structure was solved and
refined with the teXsan67 software package using direct
methods68 and expanded using Fourier techniques.69 All non-
hydrogen atoms were refined anisotropically. Hydrogen atoms
were assigned idealized positions and were included in struc-
ture factor calculations but were not refined.
[L2Ti(P y)]2(µ-N2). Crystals suitable for X-ray diffraction
studies were grown over several days at -40 °C from hexanes
solution. A large crystal was cut to the appropriate size (0.15
× 0.13 × 0.04 mm) and mounted as above. Data collection,
integration, analysis, and processing were carried out analo-
gously to that described for L2TiCl. The unit cell parameters
indicated a C-centered monoclinic cell; systematic absences
were consistent with C2/c (No. 15) and Cc (No. 9). The choice
of the acentric space group was confirmed by the successful
refinement of the model. The data were corrected for Lorentz
and polarization effects, but no correction for crystal decay was
applied.
were carried out analogously to that described for L2TiCl. The
unit cell parameters indicated a primitive monoclinic cell;
systematic absences indicated space group P21/c (No. 14). The
data were corrected for Lorentz and polarization effects, but
no correction for crystal decay was applied.
The 15 692 reflections measured were averaged (Rint
)
3.30%), yielding 5767 unique reflections. The structure was
solved and refined with the teXsan software package using
direct methods and expanded using Fourier techniques. All
non-hydrogen atoms were refined anisotropically. Hydrogen
atoms were assigned idealized positions and were included in
structure factor calculations but were not refined.
L2Ti(η2-S2). Crystals suitable for X-ray diffraction studies
were grown over several days at -40 °C from hexanes. A large
crystal was cut to the appropriate size (0.39 × 0.14 × 0.12
mm) and mounted on a quartz capillary using Paratone-N
hydrocarbon oil. Data collection, integration, analysis, and
processing were carried out analogously to that described for
L2TiCl. The unit cell parameters indicated a primitive mono-
clinic cell; systematic absences indicated space group P21/n
(No. 14). The data were corrected for Lorentz and polarization
effects, but no correction for crystal decay was applied.
The 29 535 reflections measured were averaged (Rint
)
5.63%), yielding 10 577 unique reflections. The structure was
solved and refined with the teXsan software package using
direct methods and expanded using Fourier techniques. All
non-hydrogen atoms were refined anisotropically. Hydrogen
atoms were assigned idealized positions and were included in
structure factor calculations but were not refined.
L2Ti(µ-S)2TiL[η1-NC(P h )N(SiMe3)2]. Crystals suitable for
X-ray diffraction studies were grown over several days at 25
°C from Et2O. A crystal was cut to the appropriate size (0.41
× 0.07 × 0.07 mm) and mounted as above. Data collection,
integration, analysis, and processing were carried out analo-
gously to that described for L2TiCl. The unit cell parameters
indicated a triclinic cell; the choice of the centric space group
P1h (No. 2) was confirmed by the successful refinement of the
structure. The data were corrected for Lorentz and polariza-
tion effects, but no correction for crystal decay was applied.
The 15 878 reflections measured were averaged (Rint
)
The 14 503 reflections measured were averaged (Rint
)
4.54%), yielding 7706 unique reflections. The structure was
solved and refined with the teXsan67 software package using
direct methods68 and expanded using Fourier techniques.69 All
non-hydrogen atoms were refined anisotropically. Hydrogen
atoms were assigned idealized positions and were included in
structure factor calculations but were not refined. The Flack
parameter refined to 0.0442, indicating that the correct
absolute structure was used.
2.95%), yielding 9671 unique reflections. The structure was
solved and refined with the teXsan software package using
direct methods and expanded using Fourier techniques. All
non-hydrogen atoms were refined anisotropically. Hydrogen
atoms were assigned idealized positions and were included in
structure factor calculations but were not refined.
Ack n ow led gm en t. We thank the Petroleum Re-
search Fund, administered by the American Chemical
Society, for funding and the Sloan Foundation for the
award of a fellowship to J .A.
L2Ti(O)OP y. Crystals suitable for X-ray diffraction studies
were grown over several days at -40 °C from Et2O. A crystal
of the appropriate size (0.40 × 0.23 × 0.21 mm) was mounted
as above. Data collection, integration, analysis, and processing
(72) SMART: Area-Detector Software Package; Siemens Industrial
Automation, Inc.: Madison, WI, 1993.
(73) SAINT: Area-Detector Integration Program, 4.024 ed.; Siemens
Industrial Automation, Inc.: Madison, WI, 1995.
(74) XPREP: Part of the SHELXTL Crystal-Structure Determination
Package, 5.03 ed.; Siemens Industrial Automation: Madison, WI, 1994.
(75) SADABS: Siemens Area-Detector Absorption Correction; Si-
emens Industrial Automation, Inc.: Madison, WI, 1996.
Su p p or tin g In for m a tion Ava ila ble: ORTEP views and
tables of positional and thermal parameters and bond dis-
tances and angles for all crystallographically characterized
compounds (49 pages). Ordering information is given on any
current masthead page.
OM970933C