Reactions of titanium hydrazinediido complexes with unsaturated organic substrates

Article abstract of DOI:10.1021/om900428d

Reaction of [Cp^*Ti(N^XylN){N-NPh ₂}(NH^t₂Bu)] (1a) with 1 molar equiv of phenylallene resulted in the formation of a mixture of the two metallacyclic compounds [Cp^*Ti(N^XylN) {κ

Full text of DOI:10.1021/om900428d

Organometallics 2009, 28, 4747–4757 4747
DOI: 10.1021/om900428d
Reactions of Titanium Hydrazinediido Complexes with Unsaturated
Organic Substrates
Katharina Weitershaus, Julio Lloret Fillol, Hubert Wadepohl, and Lutz H. Gade*
€
Anorganisch-Chemisches Institut, Universitat Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg,
Germany
Received May 22, 2009
Reaction of [Cp*Ti(NXylN){N-NPh2}(NHt2Bu)] (1a) with 1 molar equiv of phenylallene resulted in
the formation of a mixture of the two metallacyclic compounds [Cp*Ti(NXylN){κ2N(NPh2)-
C(CHPh)CH2}] (2a and 2b) in a molar ratio of 3:1. Comparison of the 13C and 15N NMR resonances
with the computed chemical shifts, along with an X-ray diffraction study of 2a, allowed the
assignment of the diastereomers as the cycloadducts derived from a (3,2)-cycloaddition of the allene
to the TidN bond. Upon reaction of 1a with phenylisothiocyanate, two complexes were formed in a
3:1 ratio. The major isomer, [Cp*Ti(NXylN){κ2-N(NPh2)C(NPh)S}] (4a), was isolated and identified
by X-ray diffraction to result from a [2þ2] cycloaddition of the CdS bond in PhNCS to the TidN
bond of the hydrazinediido unit, giving a four-membered metallacyclic ring with an S,N-coordina-
tion to the titanium center and an exocyclic CdN double bond. In the minor compound (4b) the two
nitrogen atoms of the thiourea unit formed in the cycloaddition are coordinated to the titanium
center. Isomerization between the cycloadducts occurs only in the direction 4b f 4a, and crossover
experiments indicate a dissociative mechanism (via a retro-cycloaddition) for the rearrangement. The
reaction of 1a with PhNCO gave analogous N,O- and N,N-coordinated cycloadducts. Finally, the
N,N-dimethyl hydrazinediido complexes reacted unspecifically with most organic azides at ambient
temperature. However, complex [Cp*Ti(NXylN){N-NMe2}(dmap)] (1c) underwent a clean and fast
reaction with trimethylsilylazide to give the N-silylated η2-hydrazido(1-) titanium azide [Cp*Ti-
(NXylN)(η2-NMe2-NSiMe3)(N3)] (8), in which the trimethylsilyl group of the azide is transferred to
the hydrazido ligand, while the azide is terminally coordinated to the titanium center.
Introduction
The focus of the study of the hydrazides of titanium has been
their significance as intermediates in hydrohydrazinations
of alkynes and related catalytic multicomponent reactions.
Mountford and co-workers reported several stoichiometric
reactions of unsaturated substrates, such as terminal and
internal alkynes, isocyanates, and CO2.2,4-6 They isolated,
inter alia, a model system for the postulated intermediate in
the hydrohydrazination of terminal alkynes and investigated
[2þ2] cycloadditions with isocyanates and CO2. On the other
hand, the reaction of a hydrazinediido complex with an
internal alkyne indicated reaction patterns involving N-N
bond cleavage of the hydrazide. The latter appears to be
more pronounced in the reactions of hydrazinediides of the
heavier group 4 metal analogues13-15 and opens up the
possibility to discover new types of reactions.
Despite the first synthesis of a titanium hydrazinediido
complex by Wiberg et al. as early as 1978,1 their coordination
chemistry and role in catalytic C-N coupling processes
have only begun to receive closer attention during the past
decade.2-10 This is remarkable in view of the large body of
published work on analogous imidotitanium complexes.11,12
*Corresponding author. Fax: (þ49)6221-545-609. E-mail: lutz.gade@
uni-hd.de.
(1) Wiberg, N.; Haering, H. W.; Huttner, G.; Friedrich, P. Chem. Ber.
1978, 111, 2708.
(2) Selby, J. D.; Schulten, C.; Schwarz, A. D.; Stasch, A.; Clot, E.;
Jones, C.; Mountford, P. Chem. Commun. 2008, 5101.
(3) Selby, J. D.; Manley, C. D.; Schwarz, A. D.; Clot, E.; Mountford,
P. Organometallics 2008, 27, 6479.
(4) Clulow, A. J.; Selby, J. D.; Cushion, M. G.; Schwarz, A. D.;
Mountford, P. Inorg. Chem. 2008, 47, 12049.
(5) Selby, J. D.; Manley, C. D.; Feliz, M.; Schwarz, A. D.; Clot, E.;
Mountford, P. Chem. Commun. 2007, 4937.
(6) Blake, A. J.; McInnes, J. M.; Mountford, P.; Nikonov, G. I.;
Swallow, D.; Watkin, D. J. J. Chem. Soc., Dalton Trans. 1999, 379.
(7) Li, Y.; Shi, Y.; Odom, A. L. J. Am. Chem. Soc. 2004, 126, 1794.
(8) Banerjee, S.; Odom, A. L. Organometallics 2006, 25, 3099.
(9) Patel, S.; Li, Y.; Odom, A. L. Inorg. Chem. 2007, 46, 6373.
(10) Thorman, J. L.; Woo, L. K. Inorg. Chem. 2000, 39, 1301.
(11) Mountford, P. Chem. Commun. 1997, 2127.
Recently, we have found that the titanium hydrazinediides
[Cp*Ti(NXylN){N-NR1R2}(L)] (R1=R2=Ph and L=NHt2Bu:
1a, R1=Ph, R2=Me and L=py: 1b, or R1=R2=Me and L=
dmap: 1c) are very active hydrohydrazination catalysts for
(13) Herrmann, H.; Lloret Fillol, J.; Wadepohl, H.; Gade, L. H.
Angew. Chem., Int. Ed. 2007, 46, 8426.
(14) Herrmann, H.; Lloret Fillol, J.; Gehrmann, T.; Enders, M.;
Wadepohl, H.; Gade, L. H. Chem.-Eur. J 2008, 14, 8131.
(15) Herrmann, H.; Wadepohl, H.; Gade, L. H. Dalton Trans. 2008,
2111.
(12) Gade, L. H.; Mountford, P. Coord. Chem. Rev. 2001, 216-217,
65.
r
2009 American Chemical Society
Published on Web 07/23/2009
pubs.acs.org/Organometallics

4748 Organometallics, Vol. 28, No. 16, 2009
Weitershaus et al.
Scheme 1. Synthesis of Compounds 2a, 2b, and 3a by [2þ2] Cycloaddition Reaction of Phenylallene to the Hydrazido Moietya
a Compound 3b in parentheses could not be isolated.
alkynes that operate at ambient temperature.16 The metalla-
cyclic compound [Cp*Ti(NXylN){κ2N(NMe2)C(Ph)CH}], ob-
tained by [2þ2] cycloaddition with phenylacetylene, was
sufficiently stable to allow its characterization by NMR spec-
troscopy in solution. However, in general it proved to be
difficult to isolate stable cycloadducts of alkynes with these
TidN-NR2 complexes.
In this study, we therefore focused our attention on the
reactivity of [Cp*Ti(NXylN){N-NR1R2}(L)] (1a,b,c) toward
other unsaturated substrates, namely, phenylallene and het-
eroallene derivatives, such as phenylisothiocyanate, phenyl-
isocyanate, and trimethylsilylazide. In all cases issues of
stereo- and regioselectivity in the cycloadditions had to be
addressed in the assignment of the molecular structures.
DFT-based modeling of the key complexes has been carried
out to support the assignment of the characterization data
and to provide insight into the bonding situation within the
cycloadducts.
similar for both compounds (11.8 Hz for complex 2a and
11.9 Hz for compound 2b). The exocyclic olefinic CH proton
deriving from phenylallene is detected at 5.60 ppm for
compound 2a and at 5.50 ppm for 2b. These chemical shifts
are in agreement with previously reported data for azatita-
nacyclobutanes.19
A series of ROESY-NMR spectra displayed the cross-
relaxation between the exocyclic olefinic proton of 2a with
the ortho-protons on the phenyl rings of the NNPh2 fragment
as well as a cross-peak between the metalated CH2 unit and
the ortho-protons of the xylyl group on the (NXylN) ligand.
These intramolecular cross-relaxation patterns are consis-
tent with the molecular structure of 2a, as represented in
Scheme 1.
The minor isomer of the mixture, compound 2b, was
found to possess a very similar NMR chemical shift pattern
to complex 2a, suggesting an isomeric structure with similar
connectivities. However, ambiguities remained concerning
the exact chemical structure of compound 2b, which proved
to be an interesting object of study for a combined experi-
mental and theoretical approach. This involved the cal-
culation of the 13C and 15N NMR chemical shifts of 2a along
with other diastereomers (DFT GIAO-B3PW91 hybrid
functional; see Experimental Section and Supporting
Information) based on their DFT-computed structures
(B3PW91 with a 6-31G(d) basis set; see the following
section). The best fit between experimental and calculated
NMR data is found for the isomeric structure 2b depicted in
Figure 1, which differs from 2a in the relative orientation of
the ancillary amidinate ligand with respect to the TiCCN
metallacycle.
Results and Discussion
[2þ2] Cycloadditions of Titanium Hydrazinediido Com-
plexes with Phenylallene. Reaction of [Cp*Ti(NXylN)-
{N-NPh2}(NHt2Bu)] (1a)16-18 with 1 molar equiv of pheny-
lallene at room temperature immediately resulted in the
formation of a mixture of two metallacyclic compounds,
[Cp*Ti(NXylN){κ2N(NPh2)C(CHPh)CH2}] (2a and 2b), in a
molar ratio of 3:1, as determined by NMR spectroscopy
(Scheme 1).
Whereas the elemental analysis of the crystalline mixture
of the two isomers confirmed the overall formulation of the
product, its two diastereomeric forms proved to be impos-
sible to separate on a preparative scale. It was only by chance
that a few single crystals of diastereomer 2a, which were
suitable for X-ray diffraction, could be isolated (vide infra).
However, we were able to assign the molecular structures of
both 2a and 2b unambiguously by NMR spectroscopy.
On the basis of the 1H NMR spectra of the product
mixture possible regioisomers resulting from a (1,2)-cycload-
dition of the allene could be discounted due to the absence of
a characteristic dCH2 olefinic set of signals. Furthermore,
Four 13C and 15N resonances were found to be particularly
diagnostic. The experimentally determined chemical shifts
are given in Figure 1 along with the computed data (in
parentheses). Both 2a and 2b result from a (3,2)-cycloaddi-
tion and are clearly distinguished from potential isomers
derived from a (2,3)-cycloaddition (with respect to the TidN
bond), one of which is displayed as complex 2c along with its
computed chemical shifts.
Variable-temperature 1H NMR studies of the mixture of
2a and 2b indicated some exchange broadening at 100 °C;
however, thermal decomposition setting in at this tempera-
ture precluded the observation of complete coalescence.
A 2D exchange spectroscopy experiment (2D-EXSY) per-
formed at 25 °C confirmed the slow interconversion of both
diastereomers in solution, which suggests that both com-
pounds may be assumed to be in equilibrium at ambient
temperature.
1
the H NMR spectrum displays two major doublet reso-
nances at 3.11 and 2.17 ppm, which are assigned to the AB
system of the CH2 group of the major diastereomer 2a, while
a similar set of two signals at 3.01 and 1.77 ppm was assigned
to the minor isomer. The 2JH-H coupling constants are very
(16) Weitershaus, K.; Wadepohl, H.; Gade, L. H. Organometallics
2009, 28 (12), 3381.
(17) Ward, B. D.; Risler, H.; Weitershaus, K.; Bellemin-Laponnaz,
€
S.; Wadepohl, H.; Gade, L. H. Inorg. Chem. 2006, 45, 7777.
(19) Trosch, D. J. M.; Collier, P. E.; Bashall, A.; Gade, L. H.;
€
(18) Weitershaus, K.; Ward, B. D.; Kubiak, R.; Muller, C.; Wadepohl,
McPartlin, M.; Mountford, P.; Radojevic, S. Organometallics 2001,
20, 3308.
H.; Doye, S.; Gade, L. H. Dalton Trans. 2009, 23, 4586.

Article
Organometallics, Vol. 28, No. 16, 2009 4749
principal bond lengths and angles. The 2-aminopyrrolinato
ligand is symmetrically κ2-coordinated to the titanium atom
˚
[Ti-N(1) 2.128(2), Ti-N(2) 2.110(2) A; N(1)-Ti-N(2)
62.90(7)°] as found previously for this type of ligands.16-18
In the four-membered metallacycle, generated by a formal
[2þ2] (3,2)-cycloaddition of the hydrazinediide and phenyl-
allene, the exocyclic bond C(13)-C(15) clearly has double-
˚
bond character [1.350(3) A], while the C(13)-C(14) distance
˚
[1.505(3) A], within the metallacyclic ring, falls in the single-
bond range. All other bond lengths and angles are similar
to the previously reported metric parameters of cycloaddi-
tion products derived from allenes and titanium imido
compounds.19
Upon reacting [Cp*Ti(NXylN){N-N(Ph)Me}(py)] (1b) with
phenylallene, two isomeric complexes were formed in a 6:1
ratio (3a,b). From this mixture only the major compound,
[Cp*TiN(NXylN){κ2N(N(Ph)Me)C(CHPh)CH2}] (3a), could
be isolated in low yield (36%). As for 2a the 13C and 15N NMR
spectra along with a 1H ROESY experiment allowed the
structural assignment of 3a, which is displayed in Scheme 1.
The small amount in which the minor component 3b was
formed made a definitive structural assignment impossible.
However, it is assumed to be the analogue of the characterized
species 2b (Scheme 1).
DFT Study of the Cycloaddition Products of the Hydrazi-
nediido Complexes 1a and 1b with Phenylallene. To gain
insight into energetics and bonding of the isomers formed
in the reaction of phenylallene with the hydrazinediido
titanium complexes 1a and 1b, both structures were modeled
by DFT using the hybrid functional B3PW91 with a 6-31G(d)
basis set for all atoms.20-23
An analysis of the possible reaction products generated by
a [2þ2] cycloaddition of the allene to the hydrazido TidN
bond revealed four possible isomers, the computed energies
and free energies of which (relative to the lowest calculated
value) are represented in Table 1.
Figure 1. Computed molecular structures of possible (3,2)-cy-
cloaddition products to the TidN bond of 1a with phenylallene.
Experimental and theoretical NMR data of compounds 2a and
2b and the calculated (2,3)-cycloaddition product 2c (not ob-
served).
(20) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.;
Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.;
Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson,
G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken,
V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev,
O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala,
P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.;
Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas,
O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.;
Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.;
Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
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Wallingford, CT, 2004.
(21) (a) Carpenter, J. E.; Weinhold, F. J. Mol. Struct.
(THEOCHEM) 1988, 169, 41. (b) Carpenter, J. E. Ph.D. Thesis, University
of Wisconsin, Madison, WI, 1987. (c) Foster, J. P.; Weinhold, F. J. Am.
Chem. Soc. 1980, 102, 7211. (d) Reed, A. E.; Weinhold, F. J. Chem. Phys.
1983, 78, 4066. (e) Reed, A. E.; Curtiss, L. A.; Weinhold, F. Chem. Rev.
1988, 88, 899. (f ) Reed, A. E.; Weinhold, F. J. Chem. Phys. 1985, 83, 1736.
(h) Reed, A. E.; Weinstock, R. B.; Weinhold, F. J. Chem. Phys. 1985, 83,
735.
Figure 2. Molecular structure of complex 2a. Hydrogen atoms are
omitted for clarity and ellipsoids drawn at the 40% probability
level. Selected bond lengths (A) and angles (deg): Ti-N(1)
2.128(2), Ti-N(2) 2.110(2), Ti-N(3) 1.974(2), Ti-C(14)
2.186(2), Ti-Cent 2.048, N(3)-N(4) 1.411(2), C(13)-C(15)
1.350(3), C(13)-C(14) 1.505(3), C(13)-N(3) 1.394(3), N(1)-
Ti-N(2) 62.90(7), C(13)-N(3)-Ti 102.3(1), N(3)-Ti-C(14)
65.46(8), N(3)-C(13)-C(14) 102.1(2), C(13)-C(14)-Ti 89.7(1).
˚
(22) Dennington, R., II; Keith, T.; Millam, J.; Eppinnett, K.; Hovell,
W. L.; Gilliland, R. GaussView, Version 3.0; Semichem, Inc.: Shawnee
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As indicated above, it proved possible to obtain single
crystals of 2a that were suitable for X-ray diffraction analysis
and therefore allowed the confirmation of the structural
assignment based on spectroscopic methods. The molecular
structure of complex 2a is depicted in Figure 2, along with the

4750 Organometallics, Vol. 28, No. 16, 2009
Weitershaus et al.
Table 1. Relative Energies and Free Energies of the Calculated [2þ2] Phenylallene Cycloaddition Isomers
a The zero point-corrected standard reaction energy and free energy of the [2þ2] cycloaddition products are given in parentheses for the
thermodynamic reaction product.
(Figure 3, bottom left) showing that the nitrogen lone pair
orbital is delocalized into the titanium atom (10%) and into
the π-antibonding orbital of the C(15)dC(13) bond (8%).
Furthermore, natural population analysis also suggests the idea
of delocalization of the N(3) lone pair into the π-antibonding of
the C(15)dC(13) bond, which is reflected in the relatively low
negative charge on N(3) (-0.47 e) and the increased partial
charge on the C(15) carbon (-0.34 e) of the C(15)-C(13)-N(3)
subsystem (Figure 3, bottom right).
[2þ2] Cycloaddition of Phenylisothiocyanate to Complexes
1a and 1b. Upon reaction of N,N-diphenyl-substituted hy-
drazinediido complex [Cp*Ti(NXylN){N-NPh2}(tBuNH2)]
(1a) with phenylisothiocyanate, two new compounds were
formed in a 3:1 ratio (Scheme 2).
Both compounds were separated and isolated by frac-
tional crystallization from a concentrated diethyl ether solu-
Figure 3. Frontier Kohn-Sham molecular orbitals (NLMOs)
tion at -18 °C. The crystals of the major isomer in the pro-
of compound 2a.
duct mixture, [Cp*Ti(NXylN){κ2-N(NPh2)C(NPh)S}] (4a),
were suitable for X-ray diffraction, and its molecular struc-
The DFT-computed energies and Gibbs free energies
of the different isomers are in qualitative agreement with
ture is depicted in Figure 4.
As a result of a [2þ2] cycloaddition of the CdS bond in
the experimentally determined product ratio (the major
experimental isomer, “type a”, being lower in energy than the
PhNCS to the TidN bond of the hydrazinediido unit, a four-
membered metallacyclic ring with a S,N-coordination to the
“type b” isomers). The calculated differences in energy and
free energy for 2a and 2b of ΔEzp=1.7 kcal mol-1 and ΔG=
titanium center and an exocyclic CdN double bond [C(13)-
˚
3
N(5), 1.280(2) A] has been formed. The Ti-S distance
1.9 kcal mol-1, respectively, are consistent with a possible
˚
˚
3
[2.398(5) A] and the Ti-N(3) bond length [2.010(1) A] are
in the range reported previously for thiolatotitanium24 and
hydrazido(1-)-titanium species.25 The angles within the
metallacyclic ring are very similar to those found in the
equilibrium between them. On the other hand, the isomers
derived form a [2þ2] cycloaddition (with 2,3 orientation
relative to the TidN bond) are computed to be energetically
disfavored by at least 9.6 kcal mol-1, which is consistent
3
with their absence in the product mixtures.
(24) (a) Shaver, A.; McCall, J. M.; Bird, P. H.; Ansari, N. Organo-
metallics 1983, 2, 1894. (b) Alcock, N. W.; Clase, H. J.; Duncalf, D. J.; Hart,
S. C.; McCamley, A.; McCormack, P. J.; Taylor, P. C. J. Organomet. Chem.
2000, 605, 45. (c) Muller, E. G.; Watkins, S. F.; Dahl, L. F. J. Organomet.
Chem. 1976, 111, 73. (d) Firth, A. V.; Stephan, D. W. Inorg. Chem. 1998, 37,
4732. (e) Kim, J. T.; Park, J. W.; Koo, S. M. Polyhedron 2000, 19, 1139.
(f ) Fenwick, A. E.; Fanwick, P. E.; Rothwell, I. P. Organometallics 2003, 22,
535.
(25) (a) Latham, I. A.; Leigh, G. J.; Huttner, G.; Jibril, I. J. Chem.
Soc., Dalton Trans. 1986, 385. (b) Hughes, D. L.; Jimenez-Tenorio, M.;
Leigh, G. J.; Walker, D. G. J. Chem. Soc., Dalton Trans. 1989, 2389.
(c) Kim, S.-J.; Jung, I. N.; Yoo, B. R.; Cho, S.; Ko, J.; Kim, S. H.; Kang, S. O.
Organometallics 2001, 20, 1501. (d) Yoon, S. C.; Bae, B. A.; Sub, I.-H.;
Park, J. T. Organometallics 1999, 18, 2049. (e) Zippel, T.; Amdt, P.; Ohff, A.;
Spannenberg, A.; Kempe, R.; Rosenthal, U. Organometallics 1998, 17,
4429. (f ) Hill, J. E.; Fanwick, P. E.; Rothwell, I. P. Inorg. Chem. 1991, 30,
In order to obtain some insight into the electronic structure of
the metallacycle in complex 2a resulting from the [2þ2] cycload-
dition and, in particular, the role of the nitrogen lone pair, the
relevant Kohn-Sham molecular orbitals were analyzed.23 The
conjugation of the double bond C(13)dC(15) with the lone pair
of the hydrazido nitrogen atom N(3) is reflected in three different
frontier MOs depicted at the top of Figure 3. The in-phase
conjugated HOMO-14 clearly represents the π-bonding inter-
action between C(15)-C(13)-N(3), while HOMO-10 itself is a
nonbonding C(15)-C(13)-N(3) fragment orbital with a node
in the central carbon atom. The HOMO of complex 2a is also a
π-orbital possessing a node between the C(15)dC(13) and the N.
This analysis has been extended by means of an NLMO study
€
1143. (g) Goetze, B.; Knizek, J.; Noth, H.; Schnick, W. Eur. J. Inorg. Chem.
2000, 1849.

Article
Organometallics, Vol. 28, No. 16, 2009 4751
structurally characterized phenylallene cycloaddition pro-
duct (2a), except that the endocyclic angle at S [80.40(5)°] is
more acute than the corresponding angle in 2a [C(13)-
C(14)-Ti, 89.7(1)°], due to the greater Ti-S distance in 4a
compared to the corresponding Ti-C bond length in 2a.
Whereas the molecular structure of 4a is thus unambigu-
ously established in the solid state, the connectivities in
solution of the isomeric metallacyclic compounds 4a and
4b were determined using 15N and 13C NMR spectroscopy
(Figure 5). The 15N chemical shift of the nitrogen atom N(5)
was found to be particularly characteristic. Coordination to
the titanium atom shifted the resonance of this nucleus
toward lower field, whereas the nitrogen atoms located in
the exocyclic position are observed at significantly higher
field. Thus, the N(5) of the major N,S-coordinated pro-
duct (4a) is detected at 245.1 ppm, while N(3) was found at
266.2 ppm. In contrast, in the minor compound (4b) the two
nitrogen atoms are coordinated to the titanium center, and
both signals are shifted toward higher frequency (N(3): 281.9
ppm and N(5): 271.1 ppm), which is consistent with the
proposed N,N coordination of the thiourea unit formed in
the cycloaddition (Figure 5).
Another characteristic signal that helps to differentiate
between both modes of ligation is the 13C NMR signal of the
carbon atom that is located in the metallacycle ring system.
This resonance is detected at 154.9 ppm in the major product
(4a), whereas the signal belonging to this carbon for the
minor product (4b) resonates at 198.1 ppm. These assign-
ments were additionally supported by the calculated DFT-
GIAO chemical shifts, which were found to be in good
agreement with the measured values (Figure 5). The case at
Figure 4. Molecular structure of complex 4a. Hydrogen atoms
are omitted for clarity and ellipsoids drawn at the 40% prob-
˚
ability level. Selected bond lengths (A) and angles (deg): Ti-
N(1) 2.136(1), Ti-N(2) 2.063 (1), Ti-N(3) 2.010(1), Ti-S 2.398
(5), Ti-Cent 2.047, N(3)-N(4) 1.409(2), C(13)-S 1.782(1),
C(13)-N(5) 1.280(2), C(13)-N(3) 1.374(2), N(1)-Ti-N(2)
64.30(5), N(3)-C(13)-S 104.3(1), C(13)-S-Ti 80.40(5),
C(13)-N(3)-Ti 106.50(9), N(3)-Ti-S 68.58(4).
Figure 5. Computed molecular structures of compounds 4a and
4b along with selected experimental and theoretical NMR data
of both complexes.
Scheme 2. [2þ2] Cycloaddition Reactions of Phenylisothiocyanate and Phenylisocyanate to the Hydrazinediido Compounds
[Cp*Ti(NXylN){N-NPh2}(NH2t Bu)] (1a) and [Cp*Ti(NXylN){N-N(Ph)Me}(py)] (1b), resulting in the formation of two isomeric metalla-
cyclic compoundsa
a Compounds in parentheses could not be isolated.

4752 Organometallics, Vol. 28, No. 16, 2009
Weitershaus et al.
Scheme 3. Interconversion of 4a and 4b and Their Relative
Energies and Free Energies
hand clearly demonstrates the usefulness of DFT methods as
an additional tool for the assignment and thus structural
elucidation for isomeric complexes in a case in which X-ray
data were not available for both species.
Finally, we note that by means of a NOESY experiment it
was possible to determine the relative disposition of the
N
4a and 4b, which was found to be similar to the orientation
established in the X-ray diffraction study. The ortho-protons
of the NNPh2 fragment display a NOESY cross-peak with
the NCH2 protons of the NXylN fragment, while such cross-
relaxation is absent for the xylyl group.
Figure 6. Molecular structure of complex 7b. Hydrogen atoms
are omitted for clarity and ellipsoids drawn at the 40% prob-
ability level. Selected bond lengths (A) and angles (deg): Ti-
N(1) 2.123(2), Ti-N(2) 2.070(2), Ti-N(3) 2.058(1), Ti-N(4)
1.984(2), Ti-Cent 2.043, N(3)-C(13) 1.397(2), N(4)-C(13)
1.379(2), C(13)-O(1) 1.222(2), N(3)-N(4) 1.391(2), N(1)-
Ti-N(2) 64.12(6), N(3)-Ti-N(5) 64.62(6), C(13)-N(5)-Ti
94.6(1), C(13)-N(4)-Ti 98.5(1).
XylN amidinato ligand in solution for both compounds
˚
Both isomers 4a and 4b were stable in solution for weeks at
ambient temperature, and no interconversion was observed.
However, previous studies had shown that titanium cycload-
dition products could undergo retro-cycloaddition.6 There-
fore, a solution of the minor isomer (4b) in deuterated
compound 4a did not lead to an exchange of the phenyl-
isothiocyanate for the tolylisothiocyanate-derived unit. This
demonstrates that 4a is not only thermodynamically more
stable than 4b but also kinetically more robust.
1
benzene was heated to 40 °C and monitored by H NMR
[2þ2] Cycloadditions of 1a,b and Phenylisocyanate. The
reaction of [Cp*Ti(NXylN){N-NPh2}(tBuNH2)] (1a) with
PhNCO resulted in the formation of two isomers in a 1:12
ratio. In contrast to the reactions discussed above, all
spectroscopic evidence indicates that the major compound
formed in this cycloaddition was the N,N-coordinated iso-
mer (6b), which could be separated from the minor compo-
nent by fractional crystallization and was isolated in an
overall yield of 30% (Scheme 2). GIAO-DFT calculations
of the 13C and 15N NMR spectroscopic data also corroborate
the structural assignment. Heating the major compound to
40 °C did not affect the product, while heating 6b to 70 °C
resulted in the formation of a complex product mixture,
possibly due to oxo-complex formation, the composition of
which could not be established.
The analogous [2þ2] cycloaddition of phenylisocyanate
to [Cp*Ti(NXylN){N-N(Ph)Me}(py)] (1b) also gave a mix-
ture of two isomers, compounds 7a and 7b (Scheme 2),
which were formed in a 2:1 ratio. In this case the 13C and
15N NMR data did not allow an unambiguous determina-
tion of the structures in solution. However, a partial
assignment of the 13C NMR data was possible. For exam-
ple the resonance of the ring carbon (of the urea unit in the
metallacycle) is shifted to lower frequency in the case of the
major N,O-coordinated isomer 7a (155.8 ppm) compared
to the minor N,N-coordinated isomer 7b, which resonates
at 164.4 ppm. The assignment of these resonances is again
spectroscopy. A slow transformation of the minor isomer
(4b) into the major isomer (4a) was observed with partial
degradation of the product. Additionally, heating of the
major isomer did not lead to an evolution in the reverse
direction. This indicates that the formation of both isomers
in the preparation of 4a,b is kinetically controlled, a notion
that is also consistent with the thermodynamic data of
the isomers computed by DFT methods (ΔEzp(4a-4b) =
5.5 kcal mol-1; ΔG(4a-4b)=5.2 kcal mol-1) and represen-
3
3
ted in Scheme 3 and Table 2.
Upon performing the cycloaddition of PhNCS with
[Cp*Ti(NXylN){N-N(Ph)Me}(py)] (1b), only the major iso-
mer 5a could be isolated (Scheme 2). However, an NMR-
tube experiment indicated the formation of a minor isomer
(∼15%). The connectivity of the major compound was
established by 1H-15N HMBC, 1H-13C HMBC, and
1H-13C HSQC NMR spectroscopy. Compound 5a was
found to display very similar 1H, 13C, and 15N NMR
spectral patterns to complex 4a, and the structural assign-
ment depicted in Scheme 2 was again backed up by a DFT
NMR(GIAO) study.
As described above, the isomerization between the
cycloadducts occurs only in the direction 4/5b f 4/5a
(Scheme 3), which is consistent with the computed free
energies. A crossover experiment was carried out to illustrate
the nature of the isomerization. By monitoring a mixture of
1
compound 4b and 10 equiv of tolylisothiocyanate by H
supported by a GIAO-DFT study (see Supporting
NMR spectroscopy at 40 °C, the formation of the isomer 4a,
free phenylisothiocyanate, and a new set of signals assigned
to the tolylisothiocyanate-derived analogue of 4a was
observed. This indicates a dissociative mechanism (via a
retro-cycloaddition) for the rearrangement of 4/5b f 4/5a.
However, performing the same experimental procedure with
Information). Further support for the possible existence
of both N,N-bonded isomers (6b and 7b) stems from
the related cycloaddition product [Ti{(NPh2)C(O)-
N(Tol)}(Me4taa)] reported by Mountford and co-workers.
For the latter, only the N,N-bonded isomer was observed
and isolated.6

Article
Organometallics, Vol. 28, No. 16, 2009 4753
Table 2. Relative Energies and Free Energies of the Calculated [2þ2] Phenylthioisocyanate Cycloaddition Isomers
a The zero point-corrected standard reaction energy and free energy of the [2þ2] cycloaddition products are given in parentheses for the
thermodynamic reaction product.
Single crystals of the minor diastereomer 7b were obtained
from a concentrated diethyl ether solution of the mixture of
isomers at room temperature. Its molecular structure is
depicted in Figure 6 along with selected bond lengths and
angles. The proposed N,N-coordination of the urea unit
ligated to the titanium atom is confirmed by an X-ray
diffraction study. The exocyclic C(13)-O(1) bond [1.222(2)
Table 3. Relative Energies and Free Energies of the Calculated
[2þ2] Phenylisocianate Cycloaddition Isomers
˚
A] is typical for a carbonyl unit. All Ti-nitrogen bonds [Ti-
˚
N, 1.984(2)-2.123(2) A] are in the range of amido-type single
bonds.26 The bite-angle of the metalated urea unit of
64.62(6)° is similar to that of the 2-aminopyrrolinato ligand
[N(1)-Ti-N(2) 64.12(6)°].
Upon heating the mixture of 7a and 7b to 40 °C, the
intensity of the signals assigned to the minor isomer de-
creased, while those of the major isomer grew in intensity.
The process was found to be irreversible, and this indicates
that the observed product ratio is not thermodynamically
controlled. This interpretation is also in agreement with the
DFT-computed free energies for the two diastereomeric
complexes. Indeed, the DFT energies of the phenylisocya-
nate derivatives 6 and 7 (Table 3) suggest again kinetic
control of the [2þ2] cycloaddition. Notably, the difference
in energy/free energy between 6a,b and 7a,b is reduced with
respect to the phenylisothiocyanate derivatives (4a,b and 5a,
a The zero point-corrected standard reaction energy and free energy
of the [2þ2] cycloaddition products are given in parentheses for the
thermodynamic reaction product.
[Cp*Ti(NXylN){N-N(Ph)Me}(py)] (1b) reacted with aryl,
adamantyl, or trimethylsilyl azides at room temperature and
formed complex product mixtures at elevated temperatures.
Only the N,N-dimethyl hydrazinediido complex [Cp*Ti-
(NXylN){N-NMe2}(dmap)] (1c) reacted with organic azides
at ambient temperature, albeit unspecifically in most cases.
However, complex 1c underwent a clean and fast reaction with
trimethylsilylazide The reaction product was identified as the
b) ((ΔEzp(6a-6b)=1.0 kcal mol-1; ΔG=1.3 kcal mol-1
;
3
3
3
(ΔEzp(7a-7b): ΔE=1.5 kcal mol-1; ΔG=1.3 kcal mol-1).
3
In other words, the energy differences for the phenylisothio-
cyanate adducts are more pronounced than that for the
corresponding phenylisocyanate derivatives.
N-silylated η2-hydrazido(1-) titanium azide [Cp*Ti(NXyl
-
N)(η2-NMe2-NSiMe3)(N3)] (8) (Scheme 4) on the basis of its
analytical and spectroscopic data. In particular the intense IR
band observed at 2066 cm-1 is characteristic for terminal
azides.28
Reaction of 1a-c with Organic Azides: Isolation of an N-
Silylated η2-Hydrazido(1-) Titanium Azide. We recently re-
ported the [3þ2] cycloaddition of organic azides, such as
trimethylsilylazide and adamantylazide, with a zirconium
hydrazinediido complex.27 In this reaction a five-membered
{ZrN4} metallacyclic compound was obtained that fragmen-
ted upon heating, liberating N2 and generating a side-on
bonded diazenide. This reactivity pattern was not observed
with the titanium hydrazido complexes discussed in this work.
Their reactivity toward azides was found to be strongly
dependent on the substitution on Nβ of the hydrazido
ligand. Neither [Cp*Ti(NXylN){N-NPh2}(tBuNH2)] (1a) nor
Due to difficulties encountered in the separation of the
product from the liberated donor ligand 4-dimethylamino-
pyridine, the isolation of the pure compound was only
achieved in low yield. Single crystals of [Cp*Ti(NXylN)(η2-
NMe2-NSiMe3)(N3)] (8), which were suitable for X-ray
diffraction, were obtained from a concentrated hexane solu-
tion at 4 °C. Its molecular structure is depicted in Figure 7
along with selected bond lengths and angles.
In complex 8 the trimethylsilyl group of the azide has been
transferred to the hydrazido ligand, which is converted to a
side-on coordinated hydrazido(-1) ligand, while the azide is
terminally coordinated to the titanium center. This ligand is
(26) (a) Allen, F. H.; Kennard, O. Chem. Des. Automation News 1993,
8, 1–31. (b) Fletcher, D. A.; McMeeking, R. F.; Parkin, D. J. Chem. Inf.
Comput. Sci. 1996, 36, 746.
(27) Gehrmann, T.; Lloret Fillol, J.; Wadepohl, H.; Gade, L. H.
Angew. Chem., Int. Ed. 2009, 48, 2152.
(28) Meyer, K. E.; Walsh, P. J.; Bergman, R. G. J. Am. Chem. Soc.
1995, 117, 474.

4754 Organometallics, Vol. 28, No. 16, 2009
Weitershaus et al.
identification of diastereomeric products the modeling and
computation of 13C and 15N NMR data have been of parti-
cular importance. The latter especially is thought to gain
increasing significance in future studies in this field. Compared
to imidotitanium complexes the chemistry of the correspond-
ing hydrazinediides (as well as their heavier group 4 metal
analogues) is still comparatively underdeveloped and merits
further systematic studies, which are ongoing in our lab.
Experimental Section
All manipulations of air- and moisture-sensitive species were
performed under an atmosphere of argon using standard Schlenk
and glovebox techniques. Solvents were predried over molecular
sieves and dried over Na/K alloy (pentane, diethyl ether), Na
(toluene), or K (THF, hexane), distilled, and stored over potas-
sium mirrors (pentane, hexane, diethyl ether, and toluene) in
Teflon valve ampules. Deuterated solvents were dried over K
(benzene-d6, toluene-d8) or CaH2 (dichloromethane-d2), vacuum
distilled, and stored under argon in Teflon valve ampules. The
ligand HNXylN and the hydrazido compounds [Cp*Ti(NXylN)-
{N-NPh2}(tBuNH2)] (1a), [Cp*Ti(NXylN){N-N(Ph)Me}(py)]
(1b), and [Cp*Ti(NXylN){N-NMe2}(dmap)] (1c) were prepared
as we described previously.16-18 All other reagents were pur-
chased from commercial suppliers. Samples for NMR spectros-
copy were prepared under argon in 5 mm Wilmad tubes equipped
with J. Young Teflon valves. NMR spectra were recorded on
Bruker Avance II 400 or Bruker Avance III 600 NMR spectro-
meters. NMR spectra are quoted in ppm and were referenced
internally relative to the residual protio-solvent (1H) or solvent
(13C) resonances orexternallyto Si(CH3)4 (29Si) and NH3(l) (15N).
Whenever necessary, NMR assignments were confirmed by the
Figure 7. Molecular structure of complex 8. Hydrogen atoms
are omitted for clarity and ellipsoids drawn at the 40% prob-
ability level. Selected bond lengths (A) and angles (deg): N(1)-
Ti 2.145(2), N(2)-Ti 2.213(2), N(3)-Ti 2.176(2), N(4)-Ti
1.951(2), N(3)-N(4) 1.446(2), N(4)-Si(1) 1.758(2), N(5)-Ti
2.088(2), N(5)-N(6) 1.198(2), N(6)-N(7) 1.160(2), Ti-Cent
2.114, N(1)-Ti-(N2) 60.58(5), N(3)-Ti-N(4) 40.55(6), Ti-
N(5)-N(6) 135.91(1), N(5)-N(6)-N(7) 177.3(2).
˚
Scheme 4. Reaction of [Cp*Ti(NXylN){N-NMe2}(dmap)] (1c)
with Trimethylsilylazide, Resulting in the Formation of a
Complex with a Side-on Bonded Hydrazido(-1) Ligand and a
Terminal Azide
1
1
use of two-dimensional H-1H or H-13C correlation experi-
ments. 15N NMR data were obtained by two-dimensional
1H correlated experiments or by direct detection using a cryo-
genically cooled direct-detection NMR probe (QNP CryoProbe).
Microanalyses were performed by the analytical services in the
€
Chemistry Department of the Universitat Heidelberg. IR spectra
were recorded on a Varian 3100 Exalibur spectrometer as KBr
pellets. Infrared data are quoted in cm-1
.
[Cp*Ti(NXylN){K2N(NPh2)C(CHPh)CH2}] (2a,b). To a solu-
tion of [Cp*Ti(NXylN){N-N(Ph)2}(tBuNH2)] (1a) (216 mg,
0.34 mmol) in toluene (3 mL) was added a solution of pheny-
lallene (40 mg, 0.34 mmol) in toluene (1 mL), leading to an
immediate change of color from green to deep red. After stirring
the reaction mixture at room temperature for 1 h all volatiles were
removed in vacuo. The residue was dissolved in pentane, and a
mixture of [Cp*Ti(NXylN){κ2N(NPh2)C(CHPh)CH2}] (2a and
2b) in a 3:1 ratio crystallized as red powder at -18 °C (130 mg,
0.20 mmol, 60%). Single crystals of the major isomer (2a) were
received from a concentrated pentane solution at -18 °C.
close to linear [N(5)-N(6)-N(7), 177.3(2)°], in correspondence
with the structures of other azido complexes (range 171.0-
179.6°, mean 177.7° for seven examples in the CSD).26 The
angle Ti-N(5)-N(6) was found to be 135.91(1)°, which is
similar to the data reported previously for titanium complexes
with terminal azide ligands.29 Finally, the side-on coordinated
hydrazido(-1) ligand is slightly unsymmetrically bonded
˚
to the titanium center, the Ti-N(4) bond [1.951(2) A] being
˚
shorter than the Ti-N(3) bond [2.176(2) A].
1
Conclusions
2a: H NMR (600.1 MHz, benzene-d6, 295 K): δ 1.36-1.31
(m, 2 H, NCH2CH2), 1.73 (s, 15 H, C5Me5), 2.16 (s, 6 H,
C6H3Me2), 2.17 (sh, 1 H, TiCH2C), 2.27-2.21 (m, 1 H,
The aim of this study has been the characterization of
[2þ2] cycloadducts that serve as models for intermediates in
Ti-catalyzed C-N coupling reactions involving hydrazines
as substrates. Whereas the cycloadduct with phenylallene is
of direct relevance to the hydrohydrazination of allenes, the
reactions with heteroallenes have shed some light on the
regiochemistry of such formal cycloaddition steps. In the
2
NCCH2), 2.48-2.42 (m, 1 H, NCCH2), 3.11 (d, JH-H
=
11.8 Hz, 1 H, TiCH2C), 3.20-3.15 (m, 1 H, NCH2), 3.43-
3.39 (m, 1 H, NCH2), 5.60 (s, 1 H, TiCH2C(CHPh)), 6.57 (s, 1 H,
para-C6H3Me2), 6.62 (s, 2 H, ortho-C6H3Me2), 6.83 (tr, 3JH-H
=
7.3 Hz, 1 H, para-Ph,), 6.88-6.79 (br m, 2 H, para-NPh2), 7.12-
7.06 (m, 6 H, meta-NPh2 and meta-Ph), 7.41-7.35 (br m, 4 H,
3
ortho-NPh2), 7.48 (d, JH-H=7.6 Hz, 2 H, ortho-Ph) ppm.
13C{1H} NMR (150.9 MHz, benzene-d6, 295 K): δ 12.0 (C5Me5),
21.6 (C6H3Me2), 23.3 (NCH2CH2), 30.9 (NCCH2), 53.1 (NCH2),
65.3 (TiCH2C), 90.4 (TiCH2C(CHPh)), 120.6 (ortho-C6H3Me2),
122.7 (para-Ph), 124.5 (para-C6H3Me2), 126.0 (C5Me5), 128.0
(ortho- and meta-Ph, overlapping with benzene-d6), 128.9 (ortho-
NPh2), 129.0 (para-NPh2), 138.4 (meta-C6H3Me2), 141.2 (ipso-
Ph), 146.4 (ipso-NPh2), 147.1 (TiCH2C), 148.6 (ipso-C6H3Me2),
171.0 (NCN) ppm, (meta-NPh2) not obsd. 15N NMR (60.8 MHz,
(29) (a) Carmalt, C. J.; Cowley, A. H.; Culp, R. D.; Jones, R. A.; Sun,
Y.-M.; Fitts, B.; Whaley, S.; Roesky, H. W. Inorg. Chem. 1997, 36, 3108.
(b) de Gil, E. R.; de Burguera, M.; Rivera, A. V.; Maxfield, P. Acta
Crystallogr. (B) 1997, 33, 578. (c) Gross, M. E.; Siegrist, T. Inorg. Chem.
1992, 31, 4898. (d) Honzicek, J.; Vinklarek, J.; Erben, M.; Cisarova, I. Acta
Crystallogr. (E) 2004, 60, m1090. (e) Haiges, R.; Boatz, J. A.; Schneider, S.;
Schroer, T.; Yousufuddin, M.; Christe, K. O. Angew. Chem., Int. Ed. 2004,
43, 3148.

Article
Organometallics, Vol. 28, No. 16, 2009 4755
benzene-d6, 295 K): δ 187.3 (NCN-Xyl), 194.5 (NCN-Xyl), 293.5
(N(NPh2)) ppm, (N(NPh2)) not obsd. IR (KBr, cm-1) mixture of
both isomers: 3016 (w), 2949 (w), 2910 (m), 2856 (m), 1586 (s),
1488 (s), 1377 (m), 1291 (s). Anal. Found (calcd for C43H48N4Ti)
mixture of both isomers: C, 76.8 (77.2); H, 7.4 (7.2); N, 8.1 (8.4).
2b: 1H NMR (600.1 MHz, benzene-d6, 295 K): δ 1.6-1.56 (m,
2 H, NCH2CH2), 1.77 (s, 15 H, C5Me5), 1.77 (1 H, TiCH2C,
overlapping with C5Me5), 1.80-1.77 (m, 1 H, NCCH2, over-
lapping with C5Me5 and TiCH2C), 2.13 (s, 6 H, C6H3Me2),
2.27-2.12 (m, 1 H, NCCH2, overlapping with NCCH2 of the
major isomer), 3.01 (d, 2JH-H=11.9 Hz, 1 H, TiCCH2), 3.10-
3.05 (m, 1 H, NCH2), 3.22-3.16 (1 H, NCH2, overlapping with
NCH2 of the major isomer), 5.50 (s, 1 H, TiCH2C(CHPh)), 6.46
(s, 2 H, ortho-C6H3Me2), 6.48 (s, 1 H, para-C6H3Me2), 6.91-
6.88 (m, 1 H, para-Ph), 6.88-6.79 (br m, 2 H, para-NPh2,
overlapping with para-NPh2 of the major isomer), 7.12-7.06
(m, 4 H, meta-NPh2, overlapping with meta-NPh2 and meta-Ph
of the major isomer), 7.15 (m, 2 H, meta-Ph), 7.41-7.35 (m, 4 H,
ortho-NPh2, overlapping with ortho-NPh2 of the major isomer),
7.53 (d, 3JH-H=10.3 Hz, 2 H, ortho-Ph) ppm. 13C{1H} NMR
(150.9 MHz, benzene-d6, 295 K): δ 12.2 (C5Me5), 21.5
(C6H3Me2), 24.6 (NCH2CH2), 29.3 (NCCH2), 51.7 (NCH2),
64.9 (TiCH2), 90.9 (TiCH2C(CHPh)), 120.4 (ortho-C6H3Me2),
122.8 ( para-Ph), 123.8 (para-C6H3Me2), 125.9 (C5Me5),
128.0 (ortho-Ph), 129.2 (ortho-NPh2, meta-NPh2, meta-Ph, or
para-NPh2), 129.3 (ortho-NPh2, meta-NPh2, meta-Ph, or para-
NPh2), 129.5 (ortho-NPh2, meta-NPh2, meta-Ph, or para-NPh2),
141.0 (ipso-Ph), 147.4 (TiCH2C), 148.0 (ipso-NPh2), 148.6 (ipso-
C6H3Me2), 172.2 (NCN) ppm. 15N NMR (60.8 MHz, benzene-d6,
295 K): δ 194.0 (NCN-Xyl), 282.7 (N(NPh2)) ppm, (NCN-Xyl),
(N(NPh2)) not obsd.
was added phenylisothiocyanate (71 μL, 0.59 mmol) in toluene
(1 mL), leading to an immediate change of color from green to deep
brown. The reaction mixture was stirred for 1 h at room tempera-
ture before all volatiles were removed in vacuo. The residue was
washed with diethyl ether, yielding a microcrystalline solid of a
mixture of two isomers, [Cp*Ti(NXylN){κ2N(NPh2)CN(Ph)S}]
(4a) and [Cp*Ti(NXylN){κ2N(NPh2)C(S)N(Ph)}] (4b), in a 3:1
ratio. Suitable crystals for X-ray diffraction of the major isomer
(4a) were obtained from a concentrated diethyl ether solution
at -18 °C (150 mg, 40% yield). The supernatant solution was
removed by filtration. The minor isomer (4b) was isolated by
evaporation of the supernatant solution (50 mg, 13% yield).
1
[Cp*Ti(NXylN){K2N(NPh2)CN(Ph)S}] (4a). H NMR (600.1
MHz benzene-d6, 295 K): δ 1.07-1.01 (m, 1 H, NCH2CH2),
1.40-1.34 (m, 1 H, NCH2CH2), 1.71 (s, 15 H, C5Me5), 2.16 (s, 6
H, C6H3Me2), 2.24-2.20 (m, 1 H, NCCH2), 2.42-2.36 (m, 1 H,
NCCH2), 3.56-3.52 (m, 1 H, NCH2), 3.76-3.72 (m, 1 H,
NCH2), 6.56 (s, 1 H, para-C6H3Me2), 6.58 (tr, 3JH-H=7.2 Hz,
1 H, para-NPh2), 6.82 (s, 2 H, ortho-C6H3Me2), 6.93-6.88 (m,
2 H, meta-NPh2 and m, 1 H, para-NPh), 6.96 (tr, 3JH-H=7.3 Hz,
3
1 H, para-NPh2), 7.10 (d, JH-H =8.2 Hz, 2 H, ortho-NPh2),
7.19-7.16 (m, 2 H, meta-NPh), 7.23-7.20 (m, 2 H, meta-NPh2),
3
3
7.36 (d, JH-H = 7.8 Hz, 2 H, ortho-NPh), 7.69 (d, JH-H
=
7.9 Hz, 2 H, ortho-NPh2) ppm. 13C{1H} NMR (150.9 MHz,
benzene-d6, 295 K): δ 12.4 (C5Me5), 21.5 (C6H3Me2), 22.8
(NCH2CH2), 30.5 (NCCH2), 54.1 (NCH2), 114.2 (ortho-NPh2),
118.3 (para-NPh2), 120.7 (ortho-C6H3Me2), 122.5 (para-NPh),
123.6 (para-NPh2), 124.2 (ortho-NPh), 124.7 (ortho-NPh2),
125.2 (para-C6H3Me2), 128.4 (meta-NPh), 128.7 (meta-NPh2),
128.9 (meta-NPh2), 129.9 (C5Me5), 138.4 (meta-C6H3Me2),
146.8 (ipso-NPh2), 146.9 (ipso-NPh2), 147.2 (ipso-C6H3Me2),
149.5 (ipso-NPh), 154.9 (NCS), 168.6 (NCN) ppm. 15N NMR
(60.8 MHz, benzene-d6, 295 K): δ 126.9 (NPh2), 193.2 (NCN-
Xyl), 201.1 (NCN-Xyl), 245.1 (NPh), 266.2 (TiNCS) ppm. IR
(KBr, cm-1): 3058 (w), 2911 (w), 2869 (w), 1598 (s), 1588 (s),
1555 (s), 1525 (s), 1491 (s), 1328 (m), 1316 (m), 1294 (m), 1262
(m), 1162 (m), 1098 (m), 1023 (m). Anal. Found (calcd for
C41H45N5STi) mixture of both isomers: C, 71.2 (71.6); H, 6.7
(6.6); N, 10.1 (10.2).
[Cp*Ti(NXylN){K2N(N(Ph)Me)C(CHPh)CH2}] (3a). To a solu-
tion of [Cp*Ti(NXylN){N-N(Ph)Me}(py)] (361 mg, 0.63 mmol)
in toluene (5 mL) was added a solution of phenylallene (74 mg,
0.63 mmol) in toluene (1 mL), leading to an immediate change of
color from red to deep red. After stirring the reaction mixture for
1 h at room temperature all volatiles were removed in vacuo. The
residue was washed with pentane, and the supernatant solution
was removed by filtration from the insoluble residue. The solid was
dried in vacuo to yield the product as a deep red powder (136 mg,
[Cp*Ti(NXylN){K2N(NPh2)C(S)N(Ph)}] (4b). 1H NMR (600.1
MHz, benzene-d6, 295 K): δ 1.01-0.94 (m, 1 H, NCH2CH2),
1.35-1.28 (m, 1 H, NCH2CH2), 1.63 (s, 15 H, C5Me5), 2.03-
1.98 (m, 1 H, NCCH2), 2.06 (s, 6 H, C6H3Me2), 2.16-2.10 (m,
1 H, NCCH2), 3.54-3.50 (m, 1 H, NCH2), 3.61-3.57 (m, 1 H,
NCH2), 6.58 (tr, 3JH-H=7.2 Hz, 1 H, para-NPh2), 6.62 (s, 1 H,
para-C6H3Me2), 6.70 (s, 2 H, ortho-C6H3Me2), 7.00-6.94 (m,
4 H, para-NPh2, meta-NPh, and para-NPh), 7.16-7.13 (m, 2 H,
meta-NPh2 overlapping with benzene-d6), 7.24-7.21 (m, 2 H,
1
0.22 mmol, 36%). H NMR (600.1 MHz, benzene-d6, 295 K):
δ 1.03 (m, 1 H, NCH2CH2), 1.27 (m, 1 H, NCH2CH2), 1.85 (s,
15 H, C5Me5), 2.12 (m, 1 H, NCCH2), 2.17 (s, 6 H, C6H3Me2), 2.30
(m, 1 H, NCCH2), 2.44 (d, 2JH-H=5.9 Hz, 1 H, TiCH2C), 2.88
(m, 1 H, NCH2), 3.09 (s, 6 H, N(Ph)Me), 3.27 (br m, 1 H,
TiCH2C), 3.34 (m, 1 H, NCH2), 5.52 (s, 1 H, TiCH2C(CHPh)),
6.57 (s, 1 H, para-C6H3Me2), 6.61 (s, 2 H, ortho-C6H3Me2),
6.70 (m, 1 H, para-N(Ph)Me), 6.78 (m, 2 H, ortho-N(Ph)Me),
6.91 (m, 2 H, meta-N(Ph)Me), 7.15 (m, 1 H, para-NPh, over-
lapping with benzene-d6), 7.25 (m, 2 H, meta-NPh), 7.59 (d,
3JH-H=6.7 Hz, 2 H, ortho-NPh) ppm. 13C{1H} NMR (150.8 MHz,
benzene-d6, 295 K): δ 12.2 (C5Me5), 21.6 (C6H3Me2), 23.1
(NCH2CH2), 30.4 (NCCH2), 41.1 (N(Ph)Me), 53.6 (NCH2),
67.4 (TiCH2C), 89.3 (br, TiCH2C(CHPh)), 112.9 (ortho-N-
(Ph)Me), 117.2 ( para-N(Ph)Me), 120.8 (ortho-C6H3Me2), 122.7
(meta-N(Ph)Me), 124.5 ( para-C6H3Me2), 125.3 (C5Me5), 126.5
(ortho-NPh), 128.0 (meta-NPh, overlapping with benzene-d6),
129.3 ( para-NPh), 138.2 (meta-C6H3Me2), 141.8 (TiCH2C-
(CHPh)), 149.1 (ipso-C6H3Me2), 150.3 (ispo-N(Ph)Me), 152.2
(ipso-NPh), 171.2 (NCN) ppm. 15N NMR (60.8 MHz, benzene-
d6, 295 K): δ 106.0 (N(Ph)Me), 185.9 (NCN-Xyl), 301.9 (NN-
(Ph)Me) ppm; (NCN-Xyl) not obsd. IR (KBr, cm-1): 2952 (w),
2910 (m), 2854 (w), 1593 (s), 1577 (s), 1561 (s), 1525 (s), 1497 (m),
1441 (m), 1375 (w), 1320 (w), 1293 (m), 1186 (m), 1162 (m),
1150 (m), 1096 (m), 1029 (m), 1012 (m), 834 (w), 815 (m), 785 (s),
743 (m), 693 (s). Anal. Found (calcd for C38H46N4Ti): C, 74.6
(75.2); H, 7.7 (7.6); N, 9.0 (9.2).
3
meta-NPh2), 7.62 (d, JH-H = 8.0 Hz, 2 H, ortho-NPh), 7.82
3
(d, JH-H = 7.9 Hz, 2 H, ortho-NPh2) ppm. 13C{1H} NMR
(150.9 MHz, benzene-d6, 295 K): δ 12.4 (C5Me5), 21.2
(C6H3Me2), 22.6 (NCH2CH2), 29.7 (NCCH2), 55.0 (NCH2),
113.9 (para-NPh2), 118.0 (ortho-NPh2), 123.5 (ortho-C6H3Me2),
123.8 (para-NPh2, meta-NPh or para-NPh), 124.4 (para-NPh2,
meta-NPh or para-NPh), 125.9 (ortho-NPh2), 126.0 (ortho-
NPh), 127.1 (para-C6H3Me2), 127.5 (meta-NPh2), 128.0 (para-
NPh2, meta-NPh, or para-NPh, overlapping with benzene-d6),
128.9 (C5Me5), 129.7 (meta-NPh2), 138.8 (meta-C6H3Me2),
146.5 (ipso-NPh2), 147.0 (ipso-NPh2), 148.2 (ipso-C6H3Me2),
149.7 (ipso-NPh), 172.1 (NCN), 198.1 (NCS) ppm. 15N NMR
(60.8 MHz, benzene-d6, 295 K): δ 126.7 (NPh2), 194.8 (NCN-
Xyl), 200.4 (NCN-Xyl), 271.7 (N(Ph)), 283.9 (N(NPh2)) ppm. IR
(KBr, cm-1): 3055 (w), 3031 (w), 2962 (m), 2911 (m), 2861 (m),
1590 (s), 1525 (s), 1492 (s), 1292 (S), 1223 (s), 1184 (s), 1095 (m),
1025 (m).
[Cp*Ti(NXylN){K2N(N(Ph)Me)CN(Ph)S}] (5a). To a solution
of [Cp*Ti(NXylN){N-N(Ph)Me}(py)] (1b) (387 mg, 0.68 mmol)
in toluene (5 mL) was added phenylisothiocyanate (81 μL,
0.67 mmol) in toluene (1 mL), leading to an immediate change
of color from red to deep brown. The reaction mixture was
[Cp*Ti(NXylN){K2N(NPh2)CN(Ph)S}] (4a) and [Cp*Ti(NXylN)-
{κ2N(NPh2)-C(S)N(Ph)}] (4b). To a solution of [Cp*Ti(NXylN)-
{N-N(Ph)2}(tBuNH2)] (1a) (371 mg, 0.59 mmol) in toluene (5 mL)

4756 Organometallics, Vol. 28, No. 16, 2009
Weitershaus et al.
stirred for 1 h at room temperature before all volatiles were
removed in vacuo. The residue was washed with diethyl ether,
yielding a microcrystalline solid of [Cp*Ti(NXylN){κ2N(N(Ph)-
Me)CN(Ph)S}] (5a) (212 mg, 0.34 mmol, 50%). 1H NMR (600.1
MHz, benzene-d6, 295 K): δ 0.75-0.67 (m, 1 H, NCH2CH2),
1.32-1.24 (m, 1 H, NCH2CH2), 1.85 (s, 15 H, C5Me5), 2.12 (s,
6 H, C6H3Me2), 2.19-2.11 (m, 1 H, NCCH2), 2.31-2.25 (m,
1 H, NCCH2), 3.27-3.23 (m, 1 H, NCH2), 3.32 (s, 3 H, N(Ph)-
Me), 3.42-3.37 (m, 1 H, NCH2), 6.52 (s, 1 H, para-C6H3Me2),
The residue was dissolved in diethyl ether, and a microcrystal-
line solid of both compounds 7a and 7b in a 2:1 ratio was
obtained at -18 °C. The supernatant solution was removed
by filtration, and the residue was dried in vacuo (yield: 344 mg,
0.55 mmol, 65%). Single crystals of [Cp*Ti(NXylN){κ2N(N(Ph)-
Me)C(O)N(Ph)}] (7b) could be obtained from a concentrated
diethyl ether solution at -18 °C.
[Cp*Ti(NXylN){K2N(N(Ph)Me)CN(Ph)O}] (7a). 1H NMR
(600.1 MHz, benzene-d6, 295 K): δ 1.04-0.98 (m, 1 H,
NCH2CH2), 1.31-1.25 (m, 1 H, NCH2CH2), 1.85 (s, 15 H,
C5Me5), 2.21-2.10 (m, 2 H, NCCH2), 2.21 (s, 6 H, C6H3Me2),
3.22-3.19 (m, 1 H, NCH2), 3.48 (s, 3 H, N(Ph)Me), 3.52-3.48
3
6.62-6.57 (m, 1 H, para-N(Ph)Me), 6.71 (d, JH-H =8.0 Hz,
2 H, ortho-N(Ph)Me), 6.73 (s, 2 H, ortho-C6H3Me2), 6.90 (tr,
3JH-H = 7.0 Hz, 1 H, para-NPh), 7.04-7.01 (m, 2 H, meta-
3
N(Ph)Me), 7.20-7.17 (m, 2 H, meta-NPh), 7.38 (d, JH-H
=
(m, 1 H, NCH2), 6.60 (s, 1 H, para-C6H3Me2), 6.85 (tr, 3JH-H
=
7.6 Hz, 2 H, ortho-NPh) ppm. 13C{1H} NMR (150.9 MHz,
benzene-d6, 295 K): δ 12.6 (C5Me5), 21.5 (C6H3Me2), 22.5
(NCH2CH2), 30.5 (NCCH2), 42.0 (N(Ph)Me), 53.7 (NCH2),
112.3 (ortho-N(Ph)Me), 116.6 (para-N(Ph)Me), 120.2 (ortho-
C6H3Me2), 122.4 (para-NPh), 124.2 (ortho-NPh), 124.9 (para-
C6H3Me2), 128.0 (meta-NPh, overlapping with benzene-d6),
128.8 (meta-N(Ph)Me), 129.5 (C5Me5), 138.4 (meta-C6H3Me2),
147.2 (ispo-C6H3Me2), 149.6 (ispo-NPh), 150.2 (ipso-N(Ph)Me),
153.1 (NCS), 168.7 (NCN) ppm. 15N NMR (60.8 MHz, benzene-
d6, 295 K): δ 192.8 (NCN-Xyl), 242.4 (NPh), 272.8 (TiNCS) ppm,
(NCN-Xyl), (N(Ph)Me) not obsd. IR (KBr, cm-1): 2949 (m), 2911
(m), 2862 (m), 1596 (s), 1566 (s), 1525 (s), 1497 (s), 1375 (w), 1318
(w), 1292 (m), 1191 (w), 1099 (m), 1026 (w), 993 (w), 918 (w), 787
(w), 760 (m), 745 (m), 693 (s). Anal. Found (calcd for
C36H38N5STi): C, 68.4 (69.1); H, 6.9 (6.9); N, 10.9 (11.2).
7.1 Hz, 1 H, para-NPh), 6.92 (s, 2 H, ortho-C6H3Me2), 6.95 (tr,
3JH-H=7.3 Hz, 1 H, para-N(Ph)Me), 7.38-7.31 (m, 4 H, meta-
N(Ph)Me and meta-NPh), 7.41-7.40 (m, 2 H, ortho-NPh), 8.04
(d, 3JH-H=7.6 Hz, 2 H, ortho-N(Ph)Me) ppm. 13C{1H} NMR
(150.9 MHz, benzene-d6, 295 K): δ 12.2 (C5Me5), 21.5 (C6H3-
Me2), 23.4 (NCH2CH2), 29.1 (NCCH2), 41.6 (N(Ph)Me), 54.6
(NCH2), 114.0 (ortho-NPh), 116.8 (para-NPh), 120.9 (ortho-
C6H3Me2), 121.3 (ortho-N(Ph)Me), 121.6 (para-N(Ph)Me),
125.6 (para-C6H3Me2), 129.0 and 128.5 (meta-N(Ph)Me and
meta-NPh, overlapping with benzene-d6), 130.2 (C5Me5), 138.6
(meta-C6H3Me2), 147.5 (ipso-N(Ph)Me), 149.4 (ipso-C6H3Me2),
153.3 (ipso-NPh), 155.8 (NCO), 170.5 (NCN) ppm. 15N NMR
(60.8 MHz, benzene-d6, 295 K): δ 192.6 (NCN-Xyl), 221.6
(N(N(Ph)Me) ppm, (N(N(Ph)Me), (NPh), (NCN-Xyl) not obs.
IR (KBr, cm-1) mixture of both isomers: 2965 (w), 2911 (m),
2860 (w), 1657 (s), 1596 (s), 1530 (s), 1498 (s), 1445 (s), 1376 (m),
1309 (s), 1299 (s), 1183 (m), 1103 (m). Anal. Found (calcd for
C36H43N5OTi) mixture of both isomers: C, 70.7 (70.9); H, 7.2
(7.1); N, 11.3 (11.5).
[Cp*Ti(NXylN){K2N(NPh2)C(O)N(Ph)}] (6b). To a solution
of [Cp*Ti(NXylN){N-N(Ph)2}(tBuNH2)] (1a) (440 mg, 0.70
mmol) in toluene (5 mL) was added phenylisocyanate (76 μL,
0.70 mmol) in toluene (1 mL), leading to an immediate change of
color from green to deep brown. The reaction mixture was
stirred for 1 h at room temperature before all volatiles were
removed in vacuo. The residue was suspended in diethyl ether,
and supernatant solution was removed by filtration. The residue
was dried in vacuo, yielding a dark brown microcrystalline solid
of [Cp*Ti(NXylN){κ2N(NPh2)C(O)N(Ph)}] (6b) (150 mg, 0.22
mmol, 31%). 1H NMR (600.1 MHz, CD2Cl2, 295 K): δ 1.18-
1.24 (m, 1 H, NCH2CH2), 1.77-1.84 (m, 1 H, NCH2CH2,
overlapping with C5Me5), 1.81 (s, 15 H, C5Me5), 2.02-2.09
(m, 1 H, NCCH2), 2.23 (s, 6 H, C6H3Me2), 2.61-2.67 (m, 1 H,
NCCH2), 3.60-3.65 (m, 1 H, NCH2), 4.00-4.04 (m, 1 H,
[Cp*Ti(NXylN){K2N(N(Ph)Me)C(O)N(Ph)}] (7b). 1H NMR
(600.1 MHz, benzene-d6, 295 K): δ 1.29-1.26 (m, 2 H,
NCH2CH2), 1.79 (s, 15 H, C5Me5), 1.90-1.84 (m, 1 H, NCCH2),
2.02 (s, 6 H, C6H3Me2), 2.32-2.23 (m, 1 H, NCCH2), 3.16 (s, 3
H, N(Ph)Me), 3.18-3.12 (m, 1 H, NCH2), 3.51-3.46 (m, 1 H,
NCH2), 6.57 (s, 2 H, ortho-C6H3Me2), 6.66-6.57 (m, 2 H, para-
N(Ph)Me and para-C6H3Me2), 6.65 (m, 2 H, ortho-N(Ph)Me),
3
6.95 (tr, JH-H = 7.2 Hz, 1 H, para-NPh), 7.05-7.02 (m,
2 H, meta-N(Ph)Me), 7.21-7.19 (m, 2 H, meta-NPh), 7.55 (d,
3JH-H=7.1 Hz, 2 H, ortho-NPh) ppm. 13C NMR (150.9 MHz,
benzene-d6, 295 K): δ 12.2 (C5Me5), 21.2 (C6H3Me2), 22.2
(NCH2CH2), 29.3 (NCCH2), 54.8 (NCH2), 65.9 (N(Ph)Me),
114.9 (ortho-N(Ph)Me), 116.5 (meta-N(Ph)Me), 120.5 (meta-
NPh), 121.3 (para-NPh), 123.1 (ortho- or para-C6H3Me2), 123.7
(ortho-NPh), 126.6 (ortho- or para-C6H3Me2), 128.0 (C5Me5,
overlapping with benzene-d6), 128.8 (para-N(Ph)Me), 138.6
(meta-C6H3Me2), 147.9 (ipso-C6H3Me2), 149.4 (ipso-NPh),
164.4 (NCO), 171.2 (NCN) ppm, (ipso-N(Ph)Me) not obsd.
15N NMR (60.8 MHz, benzene-d6, 295 K): δ 190.9 (NCN-Xyl),
267.3 (N(N(Ph)Me), (N(N(Ph)Me), (NPh), (NCN-Xyl) not
obsd.
3
NCH2), 6.54 (s, 1 H, para-C6H3Me2), 6.63 (d, JH-H = 10.0
Hz, 2 H, ortho-Ph), 6.77 (s, 2 H, ortho-C6H3Me2), 6.93-6.97 (m,
3 H, meta- and para-Ph), 7.07 (d, 3JH-H=8.2 Hz, ortho-Ph), 7.12
- 7.18 (m, 4 H, meta-, para- and para-Ph), 7.36-7.39 (m, 2 H,
meta-Ph), 7.43-7.45 (m, 2 H, ortho-Ph) ppm. 13C{1H} NMR
(150.9 MHz, CD2Cl2, 295 K): δ 12.8 (C5Me5), 21.5 (C6H3Me2),
23.1 (NCH2CH2), 29.8 (NCCH2), 55.1 (NCH2), 113.4 (ortho-
Ph), 122.4 (meta-Ph or para-Ph), 123.2 (ortho-C6H3Me2), 124.0
(ortho-Ph), 124.4 (meta-Ph or para-Ph), 124.8 (meta-Ph or para-
Ph), 125.7 (ortho-Ph), 126.6 (para-C6H3Me2), 128.2 (meta- or
para-Ph), 128.7 (meta- or para-Ph), 129.4 (C5Me5), 129.5 (meta-
Ph) 139.0 (meta-C6H3Me2), 147.4 (ispo-C6H3Me2 and ipso-Ph),
147.9 (ipso-Ph), 149.1 (ipso-Ph), 166.9 (NCO), 171.4 (NCN)
ppm. 15N NMR (60.8 MHz, CD2Cl2, 295 K): δ 192.9 (NCN-
Xyl), 242.4 (NPh), 253.9 (NNPh2) ppm, (NCN-Xyl), (NNPh2)
not obs. IR (KBr, cm-1): 3059 (w), 3030 (w), 2949 (w), 2913 (w),
2873 (w), 1659 (s), 1588 (s), 1527 (s), 1493 (s), 1481 (s), 1330 (m),
1314 (s), 1301 (m), 1190 (s), 1181 (s), 1096 (w), 1026 (w), 985 (m),
767 (m), 743 (m), 704 (s), 695 (s). Anal. Found (calcd for
C41H45N5OTi): C, 73.7 (73.3); H, 6.8 (6.8); N, 9.9 (10.4).
[Cp*Ti(NXylN)(η2-NMe2-NSiMe3)(N3)] (8). To a solution of
[Cp*Ti(NXylN){N-NMe2}(dmap)] (1c) (495 mg, 0.9 mmol) in
hexane (5 mL) was added slowly a solution of trimethylsilylazide
(73 μL, 0.9 mmol) in hexane (5 mL), leading to an immediate
change of color from red to bright orange. After half an hour
stirring at room temperature all volatiles were removed in vacuo
and the residue was dissolved in pentane. The supernatant
solution was removed by filtration from the undissolved dmap,
and the product was obtained by crystallization at 4 °C (yield:
40 mg, 0.07 mmol, 8%). Single crystals were obtained from a
[Cp*Ti(NXylN){K2N(N(Ph)Me)CN(Ph)O}] (7a) and [Cp*Ti-
(NXylN){κ2N(N(Ph)Me)-C(O)N(Ph)}] (7b). To a solution of
[Cp*Ti(NXylN){N-N(Ph)Me}(py)] (1b) (494 mg, 0.87 mmol) in
toluene (5 mL) was added phenylisocyanate (94 μL, 0.87 mmol)
in toluene (1 mL), leading to an immediate change of color from
red to deep brown. The reaction mixture was stirred for 1 h at
room temperature before all volatiles were removed in vacuo.
concentrated hexane solution at 4 °C. H NMR (600.1 MHz,
1
benzene-d6, 295 K): δ 0.30 (s, 9 H, SiMe3), 1.61-1.51 (m, 2 H,
NCH2CH2), 1.97 (s, 15 H, C5Me5), 2.08-2.01 (m, 1 H, NCCH2),
2.28 (s, 6 H, C6H3Me2), 2.33-2.26 (m, 1 H, NCCH2, overlapping
with C6H3Me2), 2.55 (s, 3 H, NMe2), 2.82 (s, 3 H, NMe2), 3.62-
3.55 (m, 1 H, NCH2), 3.83-3.79 (m, 1 H, NCH2), 6.53 (s, 2 H,
para-C6H3Me2), 6.56 (s, 1 H, ortho-C6H3Me2) ppm. 13C{1H}

Article
Organometallics, Vol. 28, No. 16, 2009 4757
Table 4. Details of the Crystal Structure Determinations of the Complexes 2a, 4a, 7b, and 8
2a
4a
7b
8
formula
cryst syst
space group
C
43H48N4Ti
C41H45N5STi
monoclinic
P21/n
12.5567(11)
18.8324(17)
15.3320(14)
95.934(2)
3606.2(6)
4
C36H43N5OTi
orthorhombic
Pbca
16.971(2)
15.809(2)
23.901(2)
C27H45N7SiTi
monoclinic
P21/c
12.007(2)
16.755(3)
14.366(2)
91.997(3)
2888.2(8)
4
monoclinic
C2/c
˚
a/A
38.976(5)
10.178(1)
20.072(3)
114.283(2)
7258(2)
8
˚
b/A
˚
c/A
β/deg
3
˚
V/A
6412(1)
8
Z
Mr
F000
668.75
2848
1.224
0.271
0.7456, 0.6898
2.0 to 26.4
687.78
1456
1.267
0.332
0.7464, 0.7031
2.0 to 32.3
609.65
2592
1.263
0.303
0.7464, 0.6713
2.0 to 30.0
543.69
1168
1.250
0.366
0.7461, 0.6867
1.7 to 30.6
dc/Mg m-3
3
μ(Mo KR) /mm-1
max., min. transmn factors
θ range/deg
index ranges (indep set) h,k,l
reflns measd
-48 ... 44, 0 ... 12, 0 ... 25 -18 ... 18, 0 ... 28, 0 ... 22 0 ... 23, -22 ... 0, -33 ... 0 -48 ... 44, 0 ... 12, 0 ... 25
67 378
7421 [0.0861]
5085
449
1.029
87 398
121 656
70 475
unique [Rint
]
12171 [0.0389]
9722
440
9383 [0.0553]
6762
396
8869 [0.0881]
5933
337
obsd [I g 2σ(I)]
params refined
GooF on F2
1.112
1.136
1.066
R indices [F > 4σ(F)] R(F), wR(F2) 0.0411, 0.0821
0.0431, 0.1124
0.0611, 0.1262
0.640, -0.281
0.0448, 0.1048
0.0813, 0.1376
0.532, -0.370
0.0476, 0.1134
0.0807, 0.1245
0.495, -0.374
R indices (all data) R(F), wR(F2)
0.0805, 0.0992
0.299, -0.357
-3
˚
largest residual peaks/e A
3
NMR (150.9 MHz, benzene-d6, 295 K): δ 4.1 (SiMe3), 12.7
(C5Me5), 21.7 (C6H3Me2), 24.3 (NCH2CH2), 30.1 (NCCH2),
52.8 (NMe2), 52.9 (NCH2), 53.9 (NMe2), 120.2 (ortho-C6H3Me2),
122.5 (para-C6H3Me2), 125.0 (C5Me5), 138.0 (meta-C6H3Me2),
150.6 (ipso-C6H3Me2), 172.8 (NCN) ppm. 29Si (79.5 MHz, ben-
zene-d6, 295 K): δ 4.39 (SiMe3) ppm. IR (KBr, cm-1): 2951 (m),
2911 (m), 2858 (m), 2066 (s), 1619 (sh), 1599 (m), 1532 (m), 1353
(m), 1248 (m). Anal. Found (calcd for C27H45N7SiTi þ DMAP):
C, 61.6 (61.3); H, 8.3 (8.3); N, 18.4 (18.9)..
X-ray Crystal Structure Determinations. Crystal data and
details of the structure determinations are listed in Table 4.
Intensity data were collected at low temperature with a Bruker
AXS Smart 1000 CCD diffractometer (Mo KR radiation,
˚
graphite monochromator, λ=0.71073 A). Data were corrected
for air and detector absorption and Lorentz and polarization
effects;32 absorption by the crystal was treated with a semiem-
pirical multiscan method.33
The structures were solved by the heavy atom method com-
bined with structure expansion by direct methods applied to
difference structure factors (complexes 2a, 4a, and 8)35 or by
conventional direct methods (complex 7b)36,37 and refined by
full-matrix least-squares methods based on F2 against all unique
reflections.37,38 All non-hydrogen atoms were given anisotropic
displacement parameters.
Hydrogen atoms were generally placed at calculated positions
and refined with a riding model. When justified by the quality of
the data, the positions of some hydrogen atoms (those on C(14)
and C(15) in complex 2a) were taken from difference Fourier
syntheses and refined.
Computational Studies
All molecular structures were optimized using the B3PW91
hybrid functional with a 6-31G(d) basis set21 for all atoms
using the GAUSSIAN03 program package.20 The natural
population analyses were performed with the NBO 3.0 facil-
ities,23 and all the orbital visualizations have been obtained with
the GaussView program.22 The molecular systems were opti-
mized using X-ray diffraction data as input. Stationary points
were verified by frequency analysis.
Theoretical NMR Shifts. All the structures used for the NMR
calculations have been carried out from DFT-optimized struc-
tures with the B3PW91 hybrid functional with a 6-31G(d) basis
set for all atoms with the GAUSSIAN03 program package:
NMR calculations have been performed with GIAO-B3PW91
hybrid functional30 with a 6-311þþG(2d, 2p) basis set for N, a
6-311þþG(d,p) basis set for S, O, C, H, and a 6-311þþG-
(2df,2p) basis set for Ti.31 The 15N NMR shifts have been
calibrated by linear regression between all the available experi-
mental data and the chemical shifts obtained from the Gaussian
output (see Supporting Information).
Acknowledgment. We thank the Deutsche Forschungs-
gemeinschaft forfunding (SFB623) and the EU fora Marie
Curie postdoctoral fellowship (to J.L.F.).
Supporting Information Available: Crystallographic informa-
tion in CIF format. This material is available free of charge via
the Internet at http://pubs.acs.org.
(32) SAINT; Bruker AXS, 2007.
(33) Blessing, R. H. Acta Crystallogr. 1995, A51, 33.
(34) Sheldrick, G. M. SADABS; Bruker AXS, 2004-2008.
(35) Beurskens, P. T. In Crystallographic Computing 3; Sheldrick,
G. M., Kr€uger, C., Goddard R., Eds.; Clarendon Press: Oxford, UK, 1985;
p 216. Beurskens, P. T.; Beurskens, G.; de Gelder, R.; Smits, J. M. M.;
Garcia-Granda, S.; Gould, R. O. DIRDIF-2008; Radboud University,
Nijmegen, The Netherlands, 2008.
(30) (a) McWeeny, R. Phys. Rev. 1926, 126, 1028. (b) Ditchfield, R.
Mol. Phys. 1974, 27, 789. (c) Dodds, J. L.; McWeeny, R.; Sadlej, A. J. Mol.
Phys. 1980, 41, 1419. (d) Wolinski, K.; Hilton, J. F.; Pulay, P. J. Am. Chem.
Soc. 1990, 112, 8251.
(31) (a) Krishnan, R.; Binkley, J. S.; Seeger, R.; Pople, J. A. J. Chem.
Phys. 1980, 72, 650. (b) Blaudeau, J.-P.; McGrath, M. P.; Curtiss, L. A.;
Radom, L. J. Chem. Phys. 1997, 107, 5016. (c) McLean, A. D.; Chandler,
G. S. J. Chem. Phys. 1980, 72, 5639.
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(36) Sheldrick, G. M. SHELXS-97; University of Gottingen: Germany,
1997.
(37) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.
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(38) Sheldrick, G. M. SHELXL-97; University of Gottingen, 1997.