Ti-Sn, Zr-Sn, and Hf-Sn heterodimetallic complexes: Stabilizing unsupported group 4-group 14 metal-metal bonds

Article abstract of DOI:10.1021/om010114z

Reaction of the tripodal amido complexes [MeSi{SiMe₂N(4-CH₃C₆H₄)}₃ ZrCl] and [MeSi{SiMe₂N(4-CH₃C₆H₄)}₃ HfCl] with LiSnPh₃ in toluene yielded the Zr-Sn and Hf-Sn complexes [MeSi{SiMe₂N(4-CH₃C₆H₄)}₃ ZrSnPh₃] (1) and [MeSi{SiMe₂N(4-CH₃C₆H₄)}₃ -HfSnPh₃] (2), while attempts to synthesize the corresponding Ti-Sn complex resulted in the oxidative coupling of the stannate to give Ph₃Sn-SnPh₃ and unidentified titanium species. More stable group 4-group 14 complexes were obtained by reaction of the triamido stannate complex [MeSi{SiMe₂N(4-CH₃C₆H₄)}₃ SnLi(OEt₂)] with the metallocene dichlorides [Cp₂MCl₂] of all three titanium group metals, giving [MeSi{SiMe₂N(4-CH₃C₆H₄)}₃ SnM(η⁵-C₅H₅)₂(Cl)] (M = Ti, 3; Zr, 4; Hf, 5). X-ray diffraction studies of 4 and 5 established Zr-Sn and Hf-Sn bond lengths of 3.02313(17) and 2.9956(3) A?, respectively.

Full text of DOI:10.1021/om010114z

Organometallics 2001, 20, 2505-2509
2505
Ti-Sn , Zr -Sn , a n d Hf-Sn Heter od im eta llic Com p lexes:
Sta bilizin g Un su p p or ted Gr ou p 4-Gr ou p 14 Meta l-Meta l
Bon d s
Matthias Lutz,†,‡ Bernd Findeis,† Matti Haukka,‡ Tapani A. Pakkanen,‡ and
Lutz H. Gade*,†
Laboratoire de Chimie Organome´tallique et de Catalyse (UMR 7513), Institut Le Bel,
Universite´ Louis Pasteur, 4 Rue Blaise Pascal, 67070 Strasbourg, France, and
Department of Chemistry, University of J oensuu, 80101 J oensuu, Finland
Received February 12, 2001
Reaction of the tripodal amido complexes [MeSi{SiMe2N(4-CH3C6H4)}3ZrCl] and [MeSi-
{SiMe2N(4-CH3C6H4)}3HfCl] with LiSnPh3 in toluene yielded the Zr-Sn and Hf-Sn
complexes [MeSi{SiMe2N(4-CH3C6H4)}3ZrSnPh3] (1) and [MeSi{SiMe2N(4-CH3C6H4)}3-
HfSnPh3] (2), while attempts to synthesize the corresponding Ti-Sn complex resulted in
the oxidative coupling of the stannate to give Ph3Sn-SnPh3 and unidentified titanium
species. More stable group 4-group 14 complexes were obtained by reaction of the triamido
stannate complex [MeSi{SiMe2N(4-CH3C6H4)}3SnLi(OEt2)] with the metallocene dichlorides
[Cp2MCl2] of all three titanium group metals, giving [MeSi{SiMe2N(4-CH3C6H4)}3SnM(η5-
C5H5)2(Cl)] (M ) Ti, 3; Zr, 4; Hf, 5). X-ray diffraction studies of 4 and 5 established Zr-Sn
and Hf-Sn bond lengths of 3.02313(17) and 2.9956(3) Å, respectively.
In tr od u ction
A fundamental difficulty in group 4-group 14 metal-
metal bond formation is the existence of energetically
low lying electron transfer reaction pathways from the
group 14 metal to the early transition metal. This prob-
lem is not unlike the situation in early-late hetero-
dinuclear transition metal complexes in which the
metals from the two ends of the d-block are directly
bonded to each other.7 In this case, the choice of a set
of chemically hard donor ligands on the early transition
metal effectively suppresses the redox reactivity, and
the integration of the donor functions into a polydentate
ligand system additionally stabilizes such compounds.8
The tripodal amido ligands developed by us9-11 were
found not only to be ideally suited for that purpose but
equally suitable as ligands for a group 14 metal complex
fragment.12 Triamidostannates were found to bind to
potentially highly oxidizing metal centers such as AgI,
AuII, and AuIII to give thermally stable heterometallic
compounds.13 The electronegative nitrogen substituents
at divalent group 14 metal centers thus appear to
During the past three decades an enormous number
of transition metal-group 14 heterodimetallic com-
pounds have been synthesized.1-3 Much of the interest
in this area derives from the fact that the formation and
transformation of transition metal-to-main group metal
bonds are crucial steps in a variety of metal-mediated
catalytic processes as well as in semiconductor growth.4,5
On going from the late to the early transition metals,
the polarity and, concomitantly, the reactivity of the
metal-metal bonds increase significantly.3 Whereas
group 4-silicon compounds have found wide-ranging
applications in some of these processes, their tin ana-
logues remain extremely rare and thus poorly studied
despite numerous efforts to develop their chemistry.1,6
A principal problem appears to be that many of the
synthetic strategies employed for M-Sn bond formation
do not work well when M is titanium, zirconium, or
hafnium.1-3
* Corresponding author. E-mail: gade@chimie.u-strasbg.fr.
† Universite´ Louis Pasteur.
‡ University of J oensuu.
(7) Reviews: (a) Stephan, D. W. Coord. Chem. Rev. 1989, 95, 41.
(b) Wheatley, N.; Kalck, P. Chem. Rev. 1999, 99, 3379. (c) Gade, L. H.
Angew. Chem., Int. Ed. 2000, 39, 2658.
(1) Holt, M. S.; Wilson, W. L.; Nelson, J . H. Chem. Rev. 1989, 89,
11.
(2) Mackay, K. M.; Nicholson, B. K. In Comprehensive Organo-
metallic Chemistry; Wilkinson, G. Stone, F. G. A.; Abel, E. W., Eds.;
Pergamon Press: New York, 1982; Vol. 6, p 1043.
(8) (a) Friedrich, S.; Memmler, H.; Gade, L. H.; Li, W.-S.; McPartlin,
M. Angew. Chem., Int. Ed. Engl. 1994, 33, 676. (b) Findeis, B.;
Schubart, M.; Platzek, C.; Gade, L. H.; Scowen, I. J .; McPartlin, M.
Chem. Commun. 1996, 219. (c) J ansen, G.; Schubart, M.; Findeis, B.;
Gade, L. H.; Scowen, I. J .; McPartlin, M. J . Am. Chem. Soc. 1998, 120,
7239.
(9) Gade, L. H.; Mahr, N. J . Chem. Soc., Dalton Trans. 1993, 489.
(10) (a) Gade, L. H.; Becker, C.; Lauher, J . W. Inorg. Chem. 1993,
32, 2308. (b) Memmler, H.; Gade, L. H.; Lauher, J . W. Inorg. Chem.
1994, 33, 3064.
(11) Schubart, M.; Findeis, B.; Gade, L. H.; Li, W.-S.; McPartlin,
M. Chem. Ber. 1995, 128, 329.
(12) (a) Hellmann, K. W.; Friedrich, S.; Gade, L. H.; Li, W.-S.;
McPartlin, M. Chem. Ber. 1995, 128, 29. (b) Memmler, H.; Kauper,
U.; Gade, L. H.; Stalke, D.; Lauher, J . W. Organometallics 1996, 15,
3637.
(3) Early examples of group 4-tin heterodimetallic complexes: (a)
Croutts, R. S. P.; Wailes, P. C. J . Chem. Soc., Chem. Commun. 1968,
260. (b) Kingston, B. F.; Lappert, M. F. J . Chem. Soc, Dalton Trans.
1972, 69. (c) Creemers, H. M.; Verbeek, J . C.; Noltes, H. G. J .
Organomet. Chem. 1968, 15, 125. The first structurally characterized
Ti-Sn bond: Zheng, W.; Stephan, D. W. Inorg. Chem. 1988, 27, 2386.
(4) Cornils, B., Herrmann, W. A., Eds. Applied Homogeneous
Catalysis with Organometallic Compounds; VCH: Weinheim, 1996.
(5) Stringfellow, G. B.; Buchan, N. I.; Larsen, C. A. In Materials
Research Society Symposia Proceedings; Hull, R., Gibson, J . M., Smith,
D. A., Eds.; Materials Research Society: Pittsburgh, PA, 1987; Vol.
94, p 245.
(6) Woo, H. G.; Tilley, T. D. Comments Inorg. Chem. 1990, 10, 37.
10.1021/om010114z CCC: $20.00 © 2001 American Chemical Society
Publication on Web 05/10/2001

2506 Organometallics, Vol. 20, No. 12, 2001
Lutz et al.
Sch em e 1. Syn th eses of th e Zr -Sn a n d Hf-Sn
Com p lexes 1 a n d 2
Sch em e 2. Syn th eses of th e Gr ou p 4-Gr ou p 14
Com p lexes 3-5
F igu r e 1. Molecular structure of compound 4. The prin-
cipal bond lengths and angles are listed in Table 1.
With the aim of obtaining heterodinuclear complexes
of greater stability, the inverse coupling strategy was
chosen. To this end, the previously characterized tri-
amido stannate complex [MeSi{SiMe2N(4-CH3C6H4)}3-
SnLi(OEt2)]13 was reacted with the metallocene dichlo-
rides [Cp2MCl2] of all three titanium group metals.
Nucleophilic substitution of one of the chloro ligands in
the metallocene dichlorides occurred cleanly in all three
cases, yielding the corresponding dinuclear complexes
as thermally stable solids (Scheme 2).
Elemental analyses as well as the NMR spectroscopic
data are consistent with their formulation as [MeSi-
{SiMe2N(4-CH3C6H4)}3SnM(η5-C5H5)2(Cl)] (M ) Ti, 3;
Zr, 4; Hf, 5), and the molecular structures are shown
in Scheme 2. As with compounds 1 and 2 we had
difficulties in our attempts to record 119Sn NMR spectra
of these complexes. We noticed this difficulty previously
in compounds in which the transition metal-tin bond
is very polar and in which the tin atom is coordinated
to amido-N atoms.
To obtain insight into the detailed molecular struc-
tures of this type of complexes and to compare the
analogous zirconium and hafnium species, single-crystal
X-ray structure analyses of both 4 and 5 were carried
out. Their molecular structures are depicted in Figures
1 and 2, and a comparative listing of their metric
parameters is given in Table 1.
The structures are isomorphic and were solved as
racemic twins in the orthorhombic space group P212121.
Since the molecular structures of 4 and 5 are virtually
identical, they will be discussed together. The tripod-
amide-tin unit is characterized by its rigid cage struc-
ture as found in related tin complexes previously
characterized by us. The peripheral tolyl groups adopt
a “lamp shade” arrangement to make space for the
Cp2MCl fragment bonded through a metal-metal bond.
The Zr-Sn bond length in 4 of 3.02313(17) Å is
significantly longer than the sum of the covalent radii
of the two metals as given by Pauling (≈2.85 Å).14
However, it is in the same range as the Zr-Sn distances
in [Zr(CO)5(SnMe3)2]2- [3.011(3) Å] and [Zr(CO)4(dppe)-
stabilize the metals with respect to oxidation by a
heterometal center to which they are bonded.
The aim of this study was to investigate whether the
use of tripodal amido ligands in the complex fragments
of either the group 4 or the group 14 metal would lead
to stable heterodinuclear compounds whose isolation
and complete structural characterization would be pos-
sible.
Resu lts a n d Discu ssion
Reaction of the previously reported tripodal amido
complexes [MeSi{SiMe2N(4-CH3C6H4)}3ZrCl] and [MeSi-
{SiMe2N(4-CH3C6H4)}3HfCl]11 with LiSnPh3 in toluene
yielded, after workup, the yellow, microcrystalline Zr-
Sn and Hf-Sn complexes [MeSi{SiMe2N(4-CH3C6H4)}3-
ZrSnPh3] (1) and [MeSi{SiMe2N(4-CH3C6H4)}3HfSnPh3]
(2) (Scheme 1). Attempts to synthesize the correspond-
ing Ti-Sn complex resulted in the oxidative coupling
of the stannate to give Ph3Sn-SnPh3 and unidentified
titanium species, reflecting the generally greater ten-
dency of titanium complexes to be reduced to Ti(III)
intermediates than their heavier homologues.
The identity of compounds 1 and 2 was established
by elemental analysis and their 1H,13C, and29Si NMR
spectra. The signal patterns in the latter indicate 3-fold
molecular symmetry and support the structural propos-
als displayed in Scheme 1. As expected, both compounds
are highly air and moisture sensitive and, if redissolved
in polar solvents such as diethyl ether or THF, slowly
decompose to give Ph3Sn-SnPh3 as the only identifiable
species.
(13) (a) Findeis, B.; Gade, L. H.; Scowen, I. J .; McPartlin, M. Inorg.
Chem. 1997, 36, 960. (b) Findeis, B.; Contel, M.; Gade, L. H.; Laguna,
M.; Gimeno, M. C.; Scowen, I. J .; McPartlin, M. Inorg. Chem. 1997,
36, 2386.
(14) Pauling, L. The Nature of the Chemical Bond, 2nd ed.; Cornell
University Press: Ithaca, NY, 1960.

Ti-Sn, Zr-Sn, and Hf-Sn Complexes
Organometallics, Vol. 20, No. 12, 2001 2507
of 2.9956(3) Å is contracted by almost 0.03 Å with
respect to the analogous Zr-Sn bond and very similar
to the Hf-Sn bond lengths determined in [(η6-C6H5-
CH3)2Hf(SnMe3)2] reported by Green and co-workers.17
There is one previous example in which two analogous
Zr-Sn and Hf-Sn complexes were structurally char-
acterized by X-ray diffraction, and this revealed a very
similar relationship between the metal-metal bond
lengths in both complexes. A decade ago, Ellis’ group
reported the syntheses and structures of [(Ph3Sn)4M-
(CO)4] (M ) Zr, Hf) and found Zr-Sn and Hf-Sn
distances of 3.086(1) and 3.063(1) Å, respectively.18 The
large intermetallic distances in these compounds are
due to the low oxidation state of the group 4 metal and
the high coordination number of 8.
A view along the metal-metal bond axis in 4 and 5
(Figure 2) illustrates the staggered arrangement of the
ligands coordinated to the two distorted (pseudo)tetra-
hedrally coordinated metal centers. The fact that the
intramolecular rotation around the M-Sn bond could
not be frozen out in low-temperature NMR studies
indicates that the barrier to such a rotation is lower
than 10 kcal‚mol-1. A closer inspection of the orientation
of the tolyl groups with respect to the ligands coordi-
nated at the Zr/Hf center in the crystal structures
reveals that the two tolyl substituents bonded to N(1)
and N(3) are slightly rotated toward each other, appar-
ently to optimize π-arene‚‚‚‚H interactions with the two
Cp rings at the group 4 metal.19 No such interaction is
possible for the third tolyl group at N(2), which lies
between the two Cp rings of the early transition metal
complex fragment.
Despite the long Zr-Sn and Hf-Sn bonds, both
compounds 4 and 5 are remarkably stable. When they
were heated at reflux in toluene, no appreciable decom-
position was observed, and as solids they may be briefly
handled in air, very likely due to the effective shielding
of the highly polar metal-metal bond by the surround-
ing bulky ligand periphery.
F igu r e 2. Molecular structure of compound 5. The prin-
cipal bond lengths and angles are listed in Table 1.
Ta ble 1. P r in cip a l Bon d Len gth s (Å) a n d
In ter bon d An gles (d eg) of Com p ou n d s 4 a n d 5
4
5
Sn(1)-N(1)
Sn(1)-N(2)
Sn(1)-N(3)
Sn(1)-Zr(1)
Zr(1)-Cl(1)
Zr(1)-C(28)
Zr(1)-C(29)
Zr(1)-C(30)
Zr(1)-C(31)
Zr(1)-C(32)
Zr(1)-C(33)
Zr(1)-C(34)
Zr(1)-C(35)
Zr(1)-C(36)
Zr(1)-C(37)
2.0973(14) Sn(1)-N(1)
2.0846(14) Sn(1)-N(2)
2.0913(14) Sn(1)-N(3)
3.02313(17) Sn(1)-Hf(1)
2.096(3)
2.081(3)
2.082(3)
2.9956(3)
2.3807(9)
2.464(5)
2.485(4)
2.505(4)
2.481(5)
2.465(5)
2.479(5)
2.466(5)
2.495(5)
2.497(4)
2.511(5)
2.4043(4)
Hf(1)-Cl(1)
2.4895(19) Hf(1)-C(28)
2.5206(19) Hf(1)-C(29)
2.5209(19) Hf(1)-C(30)
2.510(2)
2.484(2)
2.489(2)
2.476(2)
2.501(2)
2.5216(19) Hf(1)-C(36)
2.522(2) Hf(1)-C(37)
Hf(1)-C(31)
Hf(1)-C(32)
Hf(1)-C(33)
Hf(1)-C(34)
Hf(1)-C(35)
N(2)-Sn(1)-N(3) 98.00(6)
N(1)- Sn(1)-N(2) 100.43(6)
N(1)-Sn(1)-N(3) 101.65(6)
N(2)-Sn(1)-Zr(1) 115.48(4)
N(3)-Sn(1)-Zr(1) 119.25(4)
N(1)-Sn(1)-Zr(1) 118.48(4)
N(2)-Sn(1)-N(3) 97.80(13)
N(1)- Sn(1)-N(2) 100.20(13)
N(1)-Sn(1)-N(3) 101.60(14)
N(2)-Sn(1)-Hf(1) 115.14(9)
N(3)-Sn(1)-Hf(1) 119.60(9)
N(1)-Sn(1)-Hf(1) 118.81(9)
Sn(1)-Zr(1)-Cl(1) 99.197(11) Sn(1)-Hf(1)-Cl(1) 98.21(2)
Con clu sion
SnMe3]- [3.061(2) Å] reported by Ellis and co-workers.15
This observation is remarkable since the latter com-
pounds are low oxidation state zirconium complexes
with high coordination numbers and thus are expected
to possess longer Zr-Sn bonds than those in 4. It is
quite likely that the length of the metal-metal bond in
4 is largely dictated by the repulsion of the ligand
spheres of the two metal atoms. We note that metal-
metal distances in the ZrSn2 complex [Cp2Zr{Sn(CH-
(SiMe3)2}2] containing two stannylene units bonded to
zirconium, which has been reported by Piers et al., are
significantly shorter [2.8715(11) Å].16 This is consistent
with there being a partial double bond character of the
metal-metal bonding in this compound.
This study has shown that the strategy that was
successfully employed for the stabilization of tin-
transition metal bonds involving potentially oxidizing
heterometal centers works equally well in the synthesis
of novel group 4-group 14 metal complexes. Apart from
the electronic properties of the amido ligand stabilizing
the stannate units, the effective shielding of the metal-
metal bond by the ligand framework and periphery of
the tripod seems to play an important role. Current and
future research in our laboratories is aimed at the
activation of these systems toward polar and nonpolar
organic substrates.
Exp er im en ta l Section
Comparing the molecular structure of complex 5 with
that of 4, it is interesting to note that all bonds to
hafnium in 5 are significantly shorter than those to the
zirconium center in 4. In particular, the Hf-Sn distance
All manipulations and reactions were performed under
argon (desiccant P4O10, Granusic, J .T. Baker) on a high-
(17) Cloke, F. G. N.; Cox, K. P.; Green, M. L. H.; Bashkin, J .; Prout,
K. J . Chem. Soc., Chem. Commun. 1981, 117.
(18) Ellis, J . E.; Chi, K.-M.; DiMaio, A.-J .; Frerichs, S. R.; Stenzel,
J . R.; Rheingold, A. L.; Haggerty, B. S. Angew. Chem., Int. Ed. Engl.
1991, 30, 194.
(19) Such an arrangement has been previously observed in early-
late heterodinuclear complexes containing the tripod ligands: Gade,
L. H.; Schubart, M.; Findeis, B.; Fabre, S.; Bezougli, I.; Lutz, M.;
Scowen, I. J .; McPartlin, M. Inorg. Chem. 1999, 38, 5282.
(15) Ellis, J . E.; Yuen, P.; J ang, M. J . Organomet. Chem. 1996, 507,
283.
(16) (a) Whittal, R. M.; Ferguson, G.; Gallagher, J . F.; Piers, W. E.
J . Am. Chem. Soc. 1991, 113, 9867. (b) Piers, W. E.; Whittal, R. M.;
Ferguson, G.; Gallagher, J . F.; Froese, R. D. J .; Stronks, H. J .;
Krygsman, P. H. Organometallics 1992, 11, 4015.

2508 Organometallics, Vol. 20, No. 12, 2001
Lutz et al.
vacuum line using standard Schlenk techniques, or in a
glovebox. All reaction flasks were heated prior to use using
three evacuation-refill cycles. Solvents and solutions were
transferred by cannula/septa techniques. Solvents were dried
according to standard methods and saturated with argon. C6D6
used for the NMR spectroscopic measurements was degassed
by three successive “freeze-pump-thaw” cycles and stored
over 4-Å molecular sieves. Solids were separated from suspen-
sions either by centrifugation or by filtration through dried
Celite. The centrifuge employed was a Rotina 48 (Hettich
Zentrifugen, Tuttlingen, Germany), which was equipped with
a specially designed Schlenk tube rotator.20
The 1H, 13C, and 29Si NMR spectra were recorded on a
Bruker AC 200 spectrometer equipped with a B-VT-2000
variable-temperature unit (at 200.13, 50.32, and 39.76 MHz,
respectively). 1H and 13C data are listed relative to tetra-
methylsilane and were referenced using the residual pro-
tonated solvent peak (1H) or the carbon resonance (13C). 29Si
data are relative to tetramethylsilane as an external standard.
Infrared spectra were recorded on a Nicolet Magna IRTM 750
spectrometer.
Elemental analyses were carried out in the microanalytical
laboratory of the chemistry department at the University of
Wu¨rzburg using a Leco CHNS-932 microanalyzer. The com-
pounds LiSnPh3,21 [MeSi{SiMe2N(4-CH3C6H4)}3ZrCl],11 [MeSi-
{SiMe2N(4-CH3C6H4)}3HfCl],11 and the tris(amido)stannate
[MeSi{SiMe2N(4-CH3C6H4)}3SnLi(OEt2)]13 were prepared ac-
cording to procedures reported in the literature. All other
chemicals used as starting materials were obtained com-
mercially and used without further purification.
P r ep a r a tion of [MeSi{SiMe2N(4-CH3C6H4)}3Zr Sn P h 3]
(1). A mixture of solid [MeSi{SiMe2N(4-CH3C6H4)}3ZrCl] (761
mg, 1.15 mmol) and LiSnPh3 (421 mg, 1.18 mmol) was
dissolved at room temperature in toluene (20 mL) and stirred
for 2 h. Removal of the solvent in vacuo, extraction of the
residue with pentane (25 mL), and centrifugation yielded a
colorless solution, which was concentrated to about 5 mL and
stored at -30 °C. Over a period of 2 days, compound 1
precipitated as a colorless microcrystalline solid. Yield: 714
mg (64%) of the analytically pure compound. 1H NMR (200.13
MHz, C6D6, 295 K): δ 0.14 (s, 3H, SiCH3), 0.36 (s, 18H,
Si(CH3)2), 2.33 (s, 9H, CH3C6H4), 7.01-7.18 (m, Ph, Tol), 7.61-
7.68 (m, Ph). {1H}13C NMR (50.3 MHz, C6D6, 295 K): δ -15.8
(SiCH3), 2.2 (Si(CH3)2), 21.0 (CH3C6H4), 123.8 (Tol-C2,6), 129.0
(Tol-C4), 129.4 (Ph-C3,5), 130.2 (Tol-C3,5), 130.5 (Ph-C4), 137.6
(Ph-C1), 137.8 (Ph-C2,6), 148.5 (Tol-C1). {1H}29Si NMR (39.8
MHz, C6D6, 295 K): δ -95.7 (SiCH3), -4.8 (Si(CH3)2). Anal.
Calcd for C46H57N3Si4SnZr [974.23]: C, 56.71; H, 5.90; N, 4.31.
Found: C, 57.32; H, 6.11; N, 4.59.
resulting in an immediate change of color from deep orange
to dark red. The stirred reaction mixture was slowly warmed
to room temperature over a period of 3 h. The LiCl formed in
the reaction was separated by centrifugation, and the solvent
volume of the centrifugate was reduced in vacuo to about 3
mL. Storing at -35 °C yielded a red solid, which was separated
by decantation, washed with pentane (5 mL), and dried in
1
vacuo to give 403 mg (54%) of 3. H NMR (200.13 MHz, C6D6,
295 K): δ 0.27 (s, 3H, SiCH3), 0.60 (s, 18H, Si(CH3)2), 2.19 (s,
9H, CH3C6H4), 5.32 (s, 10H, C5H5), 6.98 (d, 6H, 3J HH ) 8.1 Hz,
H2,6 of CH3C6H4), 7.19 (d, 6H, 3J HH ) 8.1 Hz, H3,6 of CH3C6H4).
{1H}13C NMR (50.3 MHz, C6D6, 295 K): δ -14.2 (SiCH3), 4.3
(Si(CH3)2), 20.9 (CH3C6H4), 113.7 (C5H5), 128.5 (C2,6), 129.6
(C3,5), 130.2 (C4), 150.5 (C1). {1H}29Si NMR (39.8 MHz, C6D6,
295 K): δ -87.4 (SiCH3), 0.2 (Si(CH3)2). Anal. Calcd for C38H52
-
ClN3Si4SnTi [865.22]: C, 52.75; H, 6.06; N, 4.86. Found: C,
52.64; H, 6.42; N, 4.91.
P r ep a r a tion of [MeSi{SiMe2N(4-CH3C6H4)}3Sn Zr (η5-
C5H5)2(Cl)] (4). Toluene (15 mL) was added at -78 °C to a
stirred mixture of [(η5-C5H5)2ZrCl2] (399 mg, 1.36 mmol) and
[MeSi{SiMe2N(4-CH3C6H4)}3SnLi(OEt2)] (1.00 g, 1.36 mmol),
resulting in an immediate change of color from pale yellow to
orange. The stirred reaction mixture was slowly warmed to
room temperature over a period of 3 h. The LiCl formed in
the reaction was separated by centrifugation, and the solvent
volume of the centrifugate was reduced in vacuo to about 3
mL. Storing at -35 °C yielded an orange solid, which was
separated by decantation, washed with pentane (5 mL), and
dried in vacuo to give 729 mg (59%) of 4. Recrystallization from
a saturated solution of 4 (125 mg, 0.14 mmol) in benzene (0.5
mL) afforded suitable single crystals for the structure deter-
mination. IR (KBr): 3105 vw, 3024 vw, 2958 w, 2892 vw, 1617
m, 1697 m, 1516 s, 1499 s, 1434 w, 1365 w, 1288 m, 1250 s,
1227 s, 1182 vw, 1112 w, 1020 m, 1017 m, 945 m, 915 s, 898
1
s, 814 ws, 778 s, 708 w, 685 w, 656 w, 633 vw cm-1. H NMR
(200.13 MHz, C6D6, 295 K): δ 0.30 (s, 3H, SiCH3), 0.64 (s, 18H,
Si(CH3)2), 2.18 (s, 9H, CH3C6H4), 5.37 (s, 10H, C5H5), 7.02 (d,
3
3J HH ) 7.9 Hz, 6H, H2,6 of CH3C6H4), 7.22 (d, J HH ) 8.1 Hz,
6H, H3,5 of CH3C6H4). {1H}13C NMR (50.3 MHz, C6D6, 295 K):
δ -14.2 (SiCH3), 4.0 (Si(CH3)2), 20.9 (CH3C6H4), 112.1 (C5H5),
128.4 (C2,6), 129.9 (C3,5), 130.4 (C4), 151.2 (C1). {1H}29Si NMR
(39.8 MHz, C6D6, 295 K): δ -88.6 (SiCH3), -0.5 (Si(CH3)2).
Anal. Calcd for C38H52ClN3Si4SnZr [908.56]: C, 50.24; H, 5.77;
N, 4.62. Found: C, 50.53; H, 5.92; N, 4.87.
P r ep a r a tion of [MeSi{SiMe2N(4-CH3C6H4)}3Sn Hf(η5-
C5H5)2(Cl)] (5). An analogous procedure described to prepare
4, using 432 mg (0.59 mmol) of [MeSi{SiMe2N(4-CH3C6H4)}3-
SnLi(OEt2)] and 224 mg (0.59 mmol) of [(η5-C5H5)2HfCl2], gave
compound 5 as a bright yellow crystalline solid in 48% (276
mg) yield. IR (KBr): 3115 vw, 3024 vw, 2958 w, 2897 vw, 1610
m, 1516 m, 1502 vs, 1437 w, 1386 w, 1333 vw, 1244 s, 1224 s,
1178 vw, 1112 w, 1019 m, 949 m, 918 vs, 825 vs, 817 vs, 775
P r ep a r a tion of [MeSi{SiMe2N(4-CH3C6H4)}3HfSn P h 3]
(2). Reaction procedure as for 1 using 332 mg (0.44 mmol) of
[MeSi{SiMe2N(4-CH3C6H4)}3HfCl] and 159 mg (0.44 mmol) of
LiSnPh3. Compound 2 was obtained as a pale yellow micro-
crystalline solid in 48% (227 mg) yield. 1H NMR (200.13 MHz,
C6D6, 295 K): δ 0.13 (s, 3H, SiCH3), 0.35 (s, 18H, Si(CH3)2),
2.35 (s, 9H, CH3C6H4), 6.94-7.17 (m, Ph, Tol), 7.53-7.69 (m,
Ph). {1H}13C NMR (50.3 MHz, C6D6, 295 K): δ -16.1 (SiCH3),
2.3 (Si(CH3)2), 20.9 (CH3C6H4), 124.4 (Tol-C2,6), 129.0 (Tol-C4),
129.2 (Ph-C3,5), 130.1 (Tol-C3,5), 130.4 (Ph-C4), 137.6 (Ph-C1),
137.8 (Ph-C2,6), 148.4 (Tol-C1). {1H}29Si NMR (39.8 MHz, C6D6,
295 K): δ -99.1 (SiCH3), -5.3 (Si(CH3)2). Anal. Calcd for
1
s, 710 w, 685 vw, 653 vw cm-1. H NMR (200.13 MHz, C6D6,
295 K): δ 0.29 (s, 3H, SiCH3), 0.62 (s, 18H, Si(CH3)2), 2.19 (s,
9H, CH3C6H4), 5.28 (s, 10H, C5H5), 7.01 (d, 3J HH ) 7.8 Hz, 6H,
3
H,2,6 CH3C6H4), 7.23 (d, J HH ) 7.9 Hz, 6H, H3,5 CH3C6H4).
{1H}13C NMR (50.3 MHz, C6D6, 295 K): δ -14.3 (SiCH3), 3.9
(Si(CH3)2), 20.8 (CH3C6H4), 110.8 (C5H5), 128.3 (C2,6), 129.7
(C3,5), 130.3 (C4), 151.0 (C1). {1H}29Si NMR (39.8 MHz, C6D6,
295 K): δ -88.7 (SiCH3), -0.3 (Si(CH3)2). Anal. Calcd for
C
38H52ClHfN3Si4Sn [995.83]: C, 45.83; H, 5.26; N, 4.22.
Found: C, 45.21; H, 5.04; N, 4.14.
C
46H57HfN3Si4Sn [1061.50]: C, 52.05; H, 5.41; N, 3.96.
Found: C, 52.47; H, 5.63; N, 4.09.
X-r a y Diffr a ction Stu d y of 4 a n d 5. X-ray diffraction data
were collected with a Nonius KappaCCD diffractometer using
Mo KR radiation (λ ) 0.71073 Å). Denzo and Scalepack22
programs were used for cell refinements and data reduction.
The crystal structures of 4 and 5 were solved by direct methods
P r ep a r a t ion of [MeSi{SiMe2N(4-CH3C6H4)}3Sn Ti(η5-
C5H5)2(Cl)] (3). Toluene (15 mL) was added at -78 °C to a
stirred mixture of [(η5-C5H5)2ZrCl2] (215 mg ) 0.86 mmol) and
[MeSi{SiMe2N(4-CH3C6H4)}3SnLi(OEt2)] (632 mg ) 0.86 mmol),
(20) Hellmann, K. W.; Gade, L. H. Verfahrenstechnik 1997, 31 (5),
(22) Otwinowski, Z.; Minor, W. In Methods in Enzymology, Volume
276, Macromolecular Crystallography, Part A; Carter, C. W., J r., Sweet,
R. M., Eds.; Academic Press: New York, 1997; pp 307-326.
70.
(21) Gilman, H.; Rosenberg, S. D. J . Am. Chem. Soc. 1952, 74, 531.

Ti-Sn, Zr-Sn, and Hf-Sn Complexes
Organometallics, Vol. 20, No. 12, 2001 2509
Ta ble 2. Cr ysta l Da ta a n d Str u ctu r e Refin em en t for 4 a n d 5
4
5
empirical formula
fw
C
38H52ClN3Si4SnZr‚C6D6
C38H52ClHfN3Si4Sn‚C6D6
1079.96
992.69
temp (K)
cryst size (mm)
cryst syst
space group
unit cell dimens
a (Å)
150
150
0.40 × 0.30 × 0.30
orthorhombic
P212121
0.20 × 0.20 × 0.10
orthorhombic
P212121
12.32520(10)
17.58540(10)
21.0750(2)
90
90
90
4567.87(6)
4
1.443
0.972
2024
12.30500(10)
17.56460(10)
21.0887(2)
90
90
90
4557.95(6)
4
1.574
3.021
2152
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
D
calc (mg cm-3
)
µ(Mo KR) (mm-1
F(000)
)
2θmax (deg)
54.96
55527
10432
0.0282
50.34
45411
8152
0.0438
no. of reflns collcd
no. of indepdt reflns
Rint
max/min transm
0.2685/0.2249
10432/0/498
1.075
0.0174, 0.0436
0.456/-0.297
0.26797/0.23070
8152/0/498
1.076
0.0227, 0.0472
0.418/-0.662
no. of data/restraints/params
goodness-of-fit on F2
R1 [I > 2σ(F)], wR2a (all data)
max. ∆F (e Å-3
)
R1 ) ∑||Fo| - |Fc||/∑|Fo| and wR2 ) [∑w(Fo - Fc2)2/∑w(Fo2)2]0.5
.
a
2
using the SIR9723 and SHELXS9724 programs with the WinGX25
graphical user interface. Structure refinements were carried
out with SHELXL97.26 A multiscan absorption correction,
based on equivalent reflections (XPREP in SHELXTL v5.1),27
was applied to all data (Tmax/Tmin 0.2685/2249, 0.2680/0.2307,
for 4 and 5, respectively). All hydrogen atoms were constrained
to ride on their parent atom. Both structures were solved as
racemic twins in the orthorhombic space group P212121 (Flack
parameter 0.459(8) and 0.240(5) for 4 and 5, respectively).
Details of data collection, refinement, and crystal data are
listed in Table 2.
Ack n ow led gm en t. We thank the European Union
(TMR program, network MECATSYN), the Deutsche
Forschungsgemeinschaft (SFB 347), the CNRS (France),
and the Fonds der Chemischen Industrie for financial
support.
(23) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.;
Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna,
R. J . Appl. Crystallogr. 1999, 32, 115.
(24) Sheldrick, G. M. SHELXS97, Program for Crystal Structure
Determination; University of Go¨ttingen: Germany, 1997.
(25) Farrugia, L. J . J . Appl. Crystallogr. 1999, 32, 837.
(26) Sheldrick, G. M. SHELXL97, Program for Crystal Structure
Refinement; University of Go¨ttingen: Germany, 1997.
(27) Sheldrick, G. M. SHELXTL Version 5.1, Bruker Analytical
X-ray Systems; Bruker AXS, Inc.: Madison, WI, 1998.
Su p p or tin g In for m a tion Ava ila ble: Text detailing the
structure determination and tables of crystallographic data,
the positional and thermal parameters, and interatomic
distances and angles as well as thermal ellipsoid plots for 4
and 5. This material is available free of charge via the Internet
at http://pubs.acs.org.
OM010114Z