Synthesis and Reactivity of Group 4 Homoleptic Selenolates and Tellurolates: Lewis Base Induced Conversion to Terminal and Bridging Chalcogenides

Article abstract of DOI:10.1021/ic9600689

A combination of either salt metathesis reactions between MCl₄ (M = Zr, Hf) and (THF)₂LiSeSi(SiMe₃)₃ (THF = tetrahydrofuran) or between TiCl₃(THF)₃ and (THF)₂LiESi(SiME₃)₃ (E = Se, Te), or chalcogenolysis reactions between M(CH₂Ph)₄ (M = Zr, Hf) and HESi(SiMe₃)₃ (E = Se, Te) afforded the series of compounds M[ESi(SiMe₃)₃]₄ (M = Ti, Zr, Hf; E = Se, Te). The X-ray structures of M[TeSi(SiMe₃)₃]₄ (M = Zr, Hf) and Zr[SeSi(SiMe₃)₃]₄ have been determined and are presented for comparison. Reaction of group 4 tetrabenzyls with 3 equiv of HSeSi(SiMe₃)₃ gave the complexes M[SeSi(SiMe₃)₃]₃(CH₂Ph) (M = Ti, Zr, Hf) in high yields. Treatment of the zirconium and hafnium homoleptic tellurolates with 2 equiv of xylyl isocyanide produced the bis-L trans adducts M[TeSi(SiMe₃)₃]₄[CN(xylyl)]₂ (M = Zr, Hf) in moderate yields. The related six-coordinate DMPE adducts M[TeSi(SiMe₃)₃]₄(DMPE) (M = Zr, Hf; DMPE = 1,2-bis(dimethylphosphino)ethane) were similarly prepared. Reaction of the mono-DMPE complexes with a second equilvalent of DMPE led to the elimination of Te[Si(SiMe₃)₃]₂ and the formation of the seven-coordinate bis(tellurolate), bis(DMPE), terminal tellurides M[TeSi(SiMe₃)₃]₂(Te)(DMPE)₂ (M = Zr, Hf). Both of the tellurides have been structurally characterized. The homoleptic zirconium selenolate reacts with 1 equiv of DMPE, yielding a bright red material with the stoichiometry Zr[SeSi(SiMe₃)₃]₂(Se)(DMPE). The diphosphine DMPM (DMPM = 1,2-bis(dimethylphosphino)methane) also reacted with M[SeSi(SiMe₃)₃]₄ (M = Zr, Hf) to give the bis(μ-Se), A-frame dimers {M[SeSi(SiMe₃)₃]₂(μ-Se)(μ-η ²-DMPM)}₂ (M = Zr, Hf) in relatively low yields (40 and 23percent). The structure of the zirconium derivative has been confirmed using X-ray crystallography. Crystallographic data are as follows: Zr[SeSi(SiMe₃)₃]₄, monoclinic, P2₁/c, a = 22.6944(34) A?, b = 15.2943(55) A?, c = 22.7758(61) A?, β= 105.695(17)°, Z = 4, R = 5.29, R_w = 3.69; Hf[TeSi(SiMe₃)₃]₄, monoclinic, P2₁/c, a = 22.494(5) A?, b = 15.609(5) A?, c = 22.742(5) A?, β= 104.480(5)°, Z = 4, R = 4.48, R_w = 5.45; Hf[TeSi(SiMe₃)₃]₂(Te)(DMPE)₂, monoclinic, P2₁, a = 14.795(3) A?, b = 14.289(3) A?, c = 15.4212(2) A?, β= 102.543(3)°, Z = 2, R = 4.78, R_w = 6.70; {Zr[SeSi(SiMe₃)₃]₂(μ-Se)(μ-η ²-DMPM)}₂, monoclinic, P2₁/n, a = 14.7651(13) A?, b = 18.8579(17) A?, c = 18.6072(17) A?, β= 111.031(1)°, Z = 2, R = 8.26, R_w = 8.13.

Full text of DOI:10.1021/ic9600689

2758
Inorg. Chem. 1996, 35, 2758-2766
Synthesis and Reactivity of Group 4 Homoleptic Selenolates and Tellurolates: Lewis Base
Induced Conversion to Terminal and Bridging Chalcogenides
Christopher P. Gerlach, Victor Christou, and John Arnold*
Department of Chemistry, University of California, Berkeley, California 94720
ReceiVed January 19, 1996X
A combination of either salt metathesis reactions between MCl4 (M ) Zr, Hf) and (THF)2LiSeSi(SiMe3)3 (THF
) tetrahydrofuran) or between TiCl3(THF)3 and (THF)2LiESi(SiME3)3 (E ) Se, Te), or chalcogenolysis reactions
between M(CH2Ph)4 (M ) Zr, Hf) and HESi(SiMe3)3 (E ) Se, Te) afforded the series of compounds M[ESi-
(SiMe3)3]4 (M ) Ti, Zr, Hf; E ) Se, Te). The X-ray structures of M[TeSi(SiMe3)3]4 (M ) Zr, Hf) and Zr[SeSi-
(SiMe3)3]4 have been determined and are presented for comparison. Reaction of group 4 tetrabenzyls with 3
equiv of HSeSi(SiMe3)3 gave the complexes M[SeSi(SiMe3)3]3(CH2Ph) (M ) Ti, Zr, Hf) in high yields. Treatment
of the zirconium and hafnium homoleptic tellurolates with 2 equiv of xylyl isocyanide produced the bis-L trans
adducts M[TeSi(SiMe3)3]4[CN(xylyl)]2 (M ) Zr, Hf) in moderate yields. The related six-coordinate DMPE adducts
M[TeSi(SiMe3)3]4(DMPE) (M ) Zr, Hf; DMPE ) 1,2-bis(dimethylphosphino)ethane) were similarly prepared.
Reaction of the mono-DMPE complexes with a second equilvalent of DMPE led to the elimination of Te[Si-
(SiMe3)3]2 and the formation of the seven-coordinate bis(tellurolate), bis(DMPE), terminal tellurides M[TeSi-
(SiMe3)3]2(Te)(DMPE)2 (M ) Zr, Hf). Both of the tellurides have been structurally characterized. The homoleptic
zirconium selenolate reacts with 1 equiv of DMPE, yielding a bright red material with the stoichiometry Zr[SeSi-
(SiMe3)3]2(Se)(DMPE). The diphosphine DMPM (DMPM ) 1,2-bis(dimethylphosphino)methane) also reacted
with M[SeSi(SiMe3)3]4 (M ) Zr, Hf) to give the bis(µ-Se), A-frame dimers {M[SeSi(SiMe3)3]2(µ-Se)(µ-η2-
DMPM)}2 (M ) Zr, Hf) in relatively low yields (40 and 23%). The structure of the zirconium derivative has
been confirmed using X-ray crystallography. Crystallographic data are as follows: Zr[SeSi(SiMe3)3]4, monoclinic,
P21/c, a ) 22.6944(34) Å, b ) 15.2943(55) Å, c ) 22.7758(61) Å, â ) 105.695(17)°, Z ) 4, R ) 5.29, Rw )
3.69; Hf[TeSi(SiMe3)3]4, monoclinic, P21/c, a ) 22.494(5) Å, b ) 15.609(5) Å, c ) 22.742(5) Å, â ) 104.480(5)°,
Z ) 4, R ) 4.48, Rw ) 5.45; Hf[TeSi(SiMe3)3]2(Te)(DMPE)2, monoclinic, P21, a ) 14.795(3) Å, b ) 14.289(3)
Å, c ) 15.4212(2) Å, â ) 102.543(3)°, Z ) 2, R ) 4.78, Rw ) 6.70; {Zr[SeSi(SiMe3)3]2(µ-Se)(µ-η2-DMPM)}2,
monoclinic, P21/n, a ) 14.7651(13) Å, b ) 18.8579(17) Å, c ) 18.6072(17) Å, â ) 111.031(1)°, Z ) 2, R )
8.26, Rw ) 8.13.
Introduction
We have found that reaction of metal chalcogenolate com-
plexes with donor ligands may result in the elimination of
dialkyl- or disilylchalcogenide (ER2) and formation of soluble
metal chalcogenides.6,15 These reactions offer novel routes
toward metal chalcogenides and may be regarded as homog-
enous, solution state models for related eliminations that lead
to the formation of solid-state materials (eq 1).16 While recent
The synthesis of transition metal and main group chalco-
genolates containing the heavier members of group 16 has
expanded in recent years with the use of bulky ligands that
stabilize low-coordinate and low-molecularity compounds.1,2
Our efforts have concentrated on the synthesis of complexes
with bulky alkyl- and silylchalcogenolate ligands -EX(SiMe3)3
(E ) S, Se, Te; X ) C, Si), and we have reported an extensive
range of derivatives involving transition metal,3-7 rare earth,8-10
and main group elements.11-14
M(ER)2 f [ME]n + ER2
(1)
E ) S, Se, Te
R ) alkyl, silyl, aryl
X Abstract published in AdVance ACS Abstracts, April 1, 1996.
(1) Arnold, J. In Progress in Inorganic Chemistry; Karlin, K. D., Ed.;
John Wiley & Sons: New York, 1995; Vol. 43, p 353.
mechanistic studies have begun to shed light on chalcogenolate-
to-chalcogenide transformations,17-19 there still is much to be
(2) See the following and references cited therein for recent examples of
metal selenolates and tellurolates: Ellison, J. J.; Ruhlandt-Senge, K.;
Hope, H. H.; Power, P. P. Inorg. Chem. 1995, 34, 49. MacDonnell,
F. M.; Ruhlandt-Senge, K.; Ellison, J. J.; Holm, R. H.; Power, P. P.
Inorg. Chem. 1995, 34, 1815. Wehmschulte, R. J.; Ruhlandt-Senge,
K.; Power, P. P. Inorg. Chem. 1995, 34, 2593. Liaw, W. F.; Ou, D.
S.; Li, Y. S.; Lee, W. Z.;Chuang, C. Y.; Lee, Y. P.; Lee, G. H.; Peng,
S. M. Inorg. Chem. 1995, 34, 3747. Gardiner, M. G.; Raston, C. L.;
Tolhurst, V. A. J. Chem. Soc., Chem. Commun. 1995, 1457. Brewer,
M.; Khasnis, D.; Buretea, M.; Berardini, M.; Emge, T. J.; Brennan, J.
G. Inorg. Chem. 1994, 33, 2743-2747. Khasnis, D. V.; Brewer, M.;
Lee, J.; Emge, T. J.; Brennan, J. G. J. Am. Chem. Soc. 1994, 116,
7129. Bochmann, M.; Bwembya, G. C.; Grinter, R.; Powell, A. K.;
Webb, K. J.; Hursthouse, M. B.; Malik, K. M. A.; Mazid, M. A. Inorg.
Chem. 1994, 33, 2290. Strzelecki, A. R.; Likar, C. L.; Helsel, B. A.;
Utz, T.; Lin, M. C.; Bianconi, P. A. Inorg. Chem. 1994, 33, 5188.
Labahn, D.; Bohnen, F. M.; Herbst-Irmer, R.; Pohl, E.; Stalke, D.;
Roesky, H. W. Z. Anorg. Allg. Chem. 1994, 620, 41. Bonasia, P. J.;
Arnold, J. J. Organomet. Chem. 1993, 449, 147.
(3) Gindelberger, D. E.; Arnold, J. Inorg. Chem. 1994, 33, 6293.
(4) Gindelberger, D. E.; Arnold, J. Inorg. Chem. 1993, 32, 5813.
(5) Christou, V.; Wuller, S. P.; Arnold, J. J. Am. Chem. Soc. 1993, 115,
10545.
(6) Christou, V.; Arnold, J. J. Am. Chem. Soc. 1992, 114, 6240.
(7) Bonasia, P. J.; Christou, V.; Arnold, J. J. Am. Chem. Soc. 1993, 115,
6777.
(8) Cary, D. R.; Ball, G. E.; Arnold, J. J. Am. Chem. Soc. 1995, 117,
3492.
(9) Cary, D. R.; Arnold, J. Inorg. Chem. 1994, 33, 1791.
(10) Cary, D. R.; Arnold, J. J. Am. Chem. Soc. 1993, 115, 2520.
(11) Bonasia, P. J.; Gindelberger, D. E.; Arnold, J. Inorg. Chem. 1993,
32, 5126.
(12) Bonasia, P. J.; Mitchell, G. P.; Hollander, F. J.; Arnold, J. Inorg. Chem.
1994, 33, 1797.
(13) Seligson, A. L.; Arnold, J. J. Am. Chem. Soc. 1993, 115, 8214.
(14) Bonasia, P. J.; Arnold, J. Inorg. Chem. 1992, 31, 2508.
(15) Christou, V.; Arnold, J. Angew. Chem., Int. Ed. Engl. 1993, 32, 1450.
S0020-1669(96)00068-7 CCC: $12.00 © 1996 American Chemical Society

Homoleptic Selenolates and Tellurolates
Inorganic Chemistry, Vol. 35, No. 10, 1996 2759
Table 1. Selected Physical and Spectroscopic Data
learned. Since molecular species may be used as precursors
for technologically important solids such as II/VI materials,20-22
detailed knowledge of the factors governing reactions similar
to that shown in eq 123,24 is important for the development of
appropriate reagents.
mp (dec) 77Se/125Te
compound
color
black
orange
yellow
black
green
red
(°C)
NMR (δ)
Ti[SeSi(SiMe3)3]4
Zr[SeSi(SiMe3)3]4
Hf[SeSi(SiMe3)3]4
Ti[TeSi(SiMe3)3]4
Zr[TeSi(SiMe3)3]4
Hf[TeSi(SiMe3)3]4
Ti[SeSi(SiMe3)3]3(CH2Ph) rust
Zr[SeSi(SiMe3)3]3(CH2Ph) bright orange 172-174
Hf[SeSi(SiMe3)3]3(CH2Ph) light yellow 172-178
261-263
268-269
262-264
230-232
227-230
225-230
174-176
865
356
211
1302
459
193
828
338
206
Here we report the synthesis of M[ESi(SiMe3)3]4 and M[SeSi-
(SiMe3)3]3(CH2Ph) (M ) Ti, Zr, Hf; E ) Se, Te). The X-ray
crystal structures of the zirconium and hafnium tellurolates and
the zirconium homoleptic selenolate have been determined.
Conversion of the tellurolates to the novel terminal tellurides
M[TeSi(SiMe3)3]2(Te)(DMPE)2 (DMPE ) 1,2-bis(dimethylphos-
phino)ethane) (M ) Zr, Hf) is also reported, and the crystal-
lographic characterization of these products offers the unique
opportunity to compare the bond lengths of singly and doubly
bonded tellurium to a single metal center. The synthesis of
{M[SeSi(SiMe3)3]2(µ-Se)(µ-DMPM)}2 (DMPM ) 1,2-bis(di-
methylphosphino)methane) (M ) Zr, Hf) and X-ray structure
of the zirconium complex are also described. Except for a report
in 1970 of homoleptic -SePh derivatives,25 selenolates and
tellurolates of group 4 metals without cyclopentadienyl sup-
porting ligands are unknown. Preliminary aspects of this work
were described earlier.6
no lower valent titanium species could be separated from the
mixture and attempts at trapping the putative Ti[ESi(SiMe3)3]3
intermediate with phosphines or carbon monoxide were not
successful. We note that the related reaction between Ti[N-
(SiMe3)2]3 and 3 equiv of 2,6-(i-Pr)2C6H3OH yields the homo-
leptic titanium(IV) aryloxide, presumably by a similar path-
way.26
Physical properties and spectroscopic data for selected
compounds are collected in Table 1. All of the tellurolates may
be crystallized from hexanes; however, the more soluble
selenolates are best obtained by crystallization from hexameth-
yldisiloxane (HMDSO). In the titanium case, the mono-
HMDSO solvate was always obtained. In contrast to the
tellurolates, the homoleptic selenolates do not decompose when
exposed to dry oxygen for short periods in the solid state or in
solution (C6D6); however, all of these derivatives are moisture
sensitive. The titanium and hafnium homoleptic tellurolates are
mildly photosensitive in solution. In the solid state, slight
surface decomposition appears to half further reaction since the
materials remain spectroscopically pure. Inspection of the 77Se
and 125Te NMR data shows the typical upfield progression in
chemical shifts as the central metal atom becomes heavier.17
The values for the homoleptic tellurolates are each 400-500
ppm downfield from related values in the more electron rich
species Cp2M[TeSi(SiMe3)3]2 (M ) Ti, Zr, Hf).5
Results and Discussion
Group 4 Selenolates and Tellurolates. A combination of
either salt metathesis or chalcogenolysis reactions were suc-
cessful in preparing the complete series of group 4 homoleptic
tris(trimethylsilyl)silyl selenolates and tellurolates, as sum-
marized in eqs 2-4.
MCl4 + 4(THF)2LiSeSi(SiMe3)3 f M[SeSi(SiMe3)3]4
M ) Zr, Hf
(2)
M(CH2Ph)4 + 4HESi(SiMe3)3 f M[ESi(SiMe3)3]4 (3)
M ) Zr, Hf; E ) Se, Te
The X-ray crystal structures of Zr[TeSi(SiMe3)3]4 and Hf-
[TeSi(SiMe3)3]4 have been determined. Details on the Zr
derivative were communicated earlier,6 and the metrical pa-
rameters of the Hf analogue are, as expected, very similar. A
view of the Hf complex is provided in Figure 1, and selected
bond lengths and bond angles are given in Table 2. The Hf-
Te-Si angles average 118.8(1)°, while the Te-Hf-Te angles
vary widely from 101.73(3) to 116.28(3)°. The tetrahedral
symmetry is distorted such that two of the six angles are
significantly larger than the remaining four (Te1-Hf-Te4 )
115.78(3)°; Te2-Hf-Te3 ) 116.28(3)°). A similar distortion
occurs in the solid state structures of Zr[TeSi(SiMe3)3]4 and
Ti[S-2,3,5,6-Me4C6H]4.27 The Hf-Te bond lengths (2.707(1)-
2.731(1) Å) are well-estimated by the sum of the covaent radii
(Hf ) 1.48 Å; Te ) 1.36 Å)28 once the value is corrected for
ionic shortening (-0.072 Å) by the Schomaker-Stevenson
TiCl3(THF)3 + 3(THF)2LiESi(SiMe3)3 f Ti[ESi(SiMe3)3]4 + ...
E ) Se, Te
(4)
Related reactions between TiCl4(THF)2 and (THF)2LiSeSi-
3
(SiMe3)3 or TiCl4(NC5H5)2 and Mg[TeSi(SiMe3)3]2 also gave
the homoleptic titanium derivatives, but the reactions appeared
to be complex and yields were erratic. Although the reaction
in eq 4 apparently involves disproportionation of titanium(III),
(16) For recent examples, see the following and references cited therein:
Cheng, Y.; Emge, T. J.; Brennan, J. G. Inorg. Chem. 1994, 33, 3711.
Coleman, A. P.; Dickson, R. S.; Deacon, G. B.; Fallon, G. D.; Ke,
M.; McGregor, K.; West, B. O. Polyhedron 1994, 13, 1277. Seligson,
A. L.; Bonasia, P. J.; Arnold, J.; Yu, K.-M.; Walker, J. M.; Bourret,
E. D. Mat. Res. Soc. Symp. Proc. 1993, 282, 665. Bochmann, M.;
Webb, K. J. J. Chem. Soc., Dalton Trans. 1991, 2325. Bochmann,
M.; Webb, K. J.; Hursthouse, M. B.; Mazid, M. J. Chem. Soc., Dalton
Trans. 1991, 2317. Brennan, J. G.; Siegrist, T.; Carroll, P. J.;
Stuczynski, S. M.; Reynders, P.; Brus, L. E.; Steigerwald, M. L. Chem.
Mater. 1990, 2, 403.
(17) Gindelberger, D. E.; Arnold, J. Organometallics 1994, 13, 4462.
(18) Piers, W. E. J. Chem. Soc., Chem. Commun. 1994, 309.
(19) Piers, W. E.; Parks, D. J.; MacGillivray, L. R.; Zaworotko, M. J.
Organometallics 1994, 13, 4547.
(20) Colvin, V. L.; Schlamp, M. C.; Alivisatos, A. P. Nature 1994, 370,
354.
(21) Hoheisel, W.; Colvin, V. L.; Johnson, C. S.; Alivisatos, A. P. J. Chem.
Phys. 1994, 101, 8455.
(22) O’Brien, P. Chemtronics 1991, 5, 61.
(23) Steigerwald, M. L.; Siegrist, T.; Gyorgy, E. M.; Hessen, B.; Kwon,
Y. U.; Tanzler, S. M. Inorg. Chem. 1994, 33, 3389.
(24) Steigerwald, M. L. Polyhedron 1994, 13, 1245.
(25) Andra, K. Z. Anorg. Allg. Chem. 1970, 373, 209.
(26) Minhas, R.; Duchateau, R.; Gambarotta, S.; Bensimon, C. Inorg. Chem.
1992, 31, 4933.
(27) Corwin, D. T. J.; Corning, J. F.; Koch, S. A.; Millar, M. Inorg. Chim.
Acta 1995, 229, 335.
(28) The covalent radii of Zr (1.50 Å) and Hf (1.48 Å) were estimated by
substracting the covalent radius of carbon (0.77 Å) from the average
M-C bond lengths in the tetrabenzyls. The covalent radius of Te
(1.36 Å) and Se (1.16 Å) were calculated from structural data for
-ESi(SiMe3)3 over a range of crystallographically characterized
tellurolate and selenolate complexes (for the crystal structures of
Zr(CH2Ph)4 and Hf(CH2Ph)4, respectively, see: Davies, G. R.; Jarvis,
J. A. J.; Kilbourn, B. T.; Pioli, J. P. J. Chem. Soc., Chem. Commun.
1971, 677. Davies, G. R.; Jarvis, J. A. J.; Kilbourn, B. T. J. Chem.
Soc., Chem. Commun. 1971, 1511).

2760 Inorganic Chemistry, Vol. 35, No. 10, 1996
Gerlach et al.
Figure 1. ORTEP view of the molecular structure of Hf[TeSi-
(SiMe3)3]4. Methyl groups are omitted for clarity. Thermal ellipsoids
are plotted at the 50% probability level.
Figure 2. ORTEP view of the molecular structure of Zr[SeSi(SiMe3)3]4.
Methyl groups are omitted for clarity. Thermal ellipsoids are plotted
at the 50% probability level.
Table 2. Selected Metrical Parameters for Hf[TeSi(SiMe3)3]4 and
Zr[SeSi(SiMe3)3]4
Hf[TeSi(SiMe3)3]4
Zr[SeSi(SiMe3)3]4
tetrahedral symmetry as in the tellurolates. The average of the
Zr-Se-Si angles (123.9(2)°) is greater than the average of the
M-Te-Si angles in Zr[TeSi(SiMe3)3]4 (119.24(5)°) and Hf-
[TeSi(SiMe3)3]4 (118.8(1)°) and is presumably due to the larger
steric requirement of the -SeSi(SiMe3)3 ligand due to the shorter
Zr-Se and Se-Si bond lengths.
Bond Distances (Å)
2.7068(8) Zr-Se(1)
Hf-Te1
2.516(2)
2.522(2)
2.514(2)
2.536(2)
2.323(6)
Hf-Te2
Hf-Te3
Hf-Te4
Te-Siav
2.7311(8)
2.7165(8)
2.7121(9)
2.534(3)
Zr-Se(2)
Zr-Se(3)
Zr-Se(4)
Se-Siav
Bond Angles (deg)
Reaction of the group 4 homoleptic benzyls with 3 equiv of
HSeSi(SiMe3)3 afforded the tris(selenolates) in high yields (eq
5). Generally, the reactions were quite clean, although the Zr
Hf-Te1-Si1
Hf-Te2-Si5
Hf-Te3-Si9
Hf-Te4-Si13
Te1-Hf-Te2
Te1-Hf-Te3
Te1-Hf-Te4
Te2-Hf-Te3
Te2-Hf-Te4
Te3-Hf-Te4
123.57(7)
119.66(8)
114.55(7)
117.61(7)
107.80(3)
101.73(3)
115.78(3)
116.28(3)
108.22(3)
107.25(3)
Zr-Se1-Si1
Zr-Se2-Si5
Zr-Se3-Si9
Zr-Se4-Si13
Se1-Zr-Se2
Se1-Zr-Se3
Se1-Zr-Se4
Se2-Zr-Se3
Se2-Zr-Se4
Se3-Zr-Se4
126.19(9)
119.35(8)
123.72(9)
126.29(9)
103.67(5)
114.89(6)
107.86(5)
106.88(5)
114.85(5)
108.84(5)
M(CH2Ph)4 + 3HSeSi(SiMe3)3 f M[SeSi(SiMe3)3]3(CH2Ph)
M ) Ti, Zr, Hf
(5)
derivative was always contaminated with a small amount of
the tetraselenolate (ca. 5%). Analogous reactions with HTeSi-
(SiMe3)3 were not as selective due to its higher reactivity as
compared to the selenol. The benzyl groups are bound in a
normal η1-fashion as evidenced by the downfield resonances
equation.29 Nevertheless, the observed distances are slightly
shorter (0.04-0.06 Å) and may be indicative of some multiple
bond character. In this regard, it is interesting to note that recent
XR calculations of the bonding in the model complex Zr-
(TeSiH3)4 predict that the π-symmetry MOs constructed from
the tellurium 5p orbitals and the zirconium d orbitals are
approximately one-third metal d in character. While π-interac-
tions between the heavier chalcogens and early transition metals
have typically been thought of as relatively weak, clearly they
are likely to be more favored in cases where the metal is severely
electron deficient (i.e. formally eight electrons in M(ER)4).
An ORTEP view of Zr[SeSi(SiMe3)3]4 is shown in Figure 2,
and selected bond lengths and angles are given in Table 2. The
structure consists of well-separated molecules with the zirconium
coordinated by the four selenium atoms in a pseudo-tetrahedral
fashion. The sum of covalent radii (2.66 Å) corrected for ionic
shortening (-0.10 Å) gives a predicted value of 2.56 Å for the
Zr-Se bond distances. The observed bond lengths of 2.514(1)-
2.522(2) Å are thus about 0.04 Å shorter, again possibly due to
multiple bond character. The range of Se-Zr-Se angles
(103.67(5)-114.89(6)°) indicates a similar distortion from
1
of the ortho protons in their H NMR spectra and the absence
of low-energy νCH in the IR spectrum.31,32 The compounds have
nearly identical melting (decomposition) points that are lower
than those observed for the homoleptic selenolates (Table 1).
The 77Se NMR spectra possess singlets that are all shifted upfield
from the values of the resonances observed in the homoleptic
selenolates. Nevertheless, the upfield progression of the chemi-
cal shifts as the atomic number of the central metal atom
increases mirrors the trend observed within their homoleptic
counterparts (Table 1). The chemical shifts of heavy nuclei
are strongly influenced by low-energy, electronic excited states33
such that compounds with higher-energy (visible) absorptions
display higher-field NMR shifts and vice versa.17 Thus, as
expected, the lowest-energy absorptions in the electronic spectra
(31) Jordan, R. F.; LaPointe, R. E.; Bradley, P. K.; Baenziger, N.
Organometallics 1989, 8, 2892.
(32) Jordan, R. F.; LaPointe, R. E.; Baenziger, N.; Hinch, G. D. Organo-
metallics 1990, 9, 1539.
(33) Karplus, M.; Pople, J. A. J. Chem. Phys. 1963, 38, 2803.
(29) Schomaker, V.; Stevenson, D. P. J. Am. Chem. Soc. 1941, 63, 37.
(30) Kaltsoyannis, N. J. Chem. Soc., Dalton Trans. 1994, 1391.

Homoleptic Selenolates and Tellurolates
Inorganic Chemistry, Vol. 35, No. 10, 1996 2761
Table 3. Selected Metrical Parameters for Hf[TeSi(SiMe3)3]2(Te)-
(DMPE)2
of the M[SeSi(SiMe3)3]3(CH2Ph) complexes are blue-shifted
compared to those in the analogous tetraselenolates.34
Attempts to prepare mixed chalcogenolate compounds by
reactions of Zr[SeSi(SiMe3)3]4 with 2 equiv of alcohol or phenol
resulted in complete alcoholysis (eq 6). These reactions were
Bond Distances (Å)
Hf-Te1
Hf-Te2
Hf-Te3
3.019(1)
2.918(2)
2.637(2)
Hf-Pav
Te1-Si1
Te2-Si5
2.769(8)
2.525(6)
2.521(6)
Zr(SeR)4 + 2R′OH f 1/2Zr(SeR)4 + 1/2Zr(OR′)4 + 2HSeR
Bond Angles (deg)
Te1-Hf-Te2
Te1-Hf-Te3
Te2-Hf-Te3
P1-Hf-P2
86.05(4)
105.31(5)
168.51(6)
70.6(5)
Te1-Hf-P2
Te1-Hf-P4
P1-Hf-P3
Hf-Te1-Si1
Hf-Te2-Si5
71.5(3)
74.6(4)
74.2(3)
128.26(14)
142.31(16)
R ) Si(SiMe3)3; R′ ) Me, But, 2,6-Pri2C6H3
(6)
quantitative as judged by 1H NMR spectroscopy and no
M(SeR)4-x(OR′)x species were detected. The identities of the
alkoxides were verified by comparison of spectroscopic data
to literature values. Alcoholysis with 1 equiv of catechol
proceeded analogously, but the sterically encumbered phenol
2,6-But2C6H3OH did not react, even after prolonged heating.
The alkoxide-selenolate Ti[SeSi(SiMe3)3]2(OEt)2 was pro-
P3-Hf-P4
69.2(6)
A 1 equiv amount of DMPE also reacts with the zirconium
and hafnium tellurolates, forming related six-coordinate, cis
adducts (eq 9). The compounds were isolated from hexanes as
RTe
Te
M
RTe
M
RTe
P
P
RTe
P
P
35
DMPE
DMPE
–TeR2
duced by heating a C7D8 solution of Ti(CH2Ph)2(OEt)2 with
M
(9)
P
TeR
TeR
2 equiv of HSeSi(SiMe3)3 (eq 7). The product is stable in
RTe
RTe
P
TeR
TeR
M = Zr, Hf
R = Si(SiMe3)3
Ti(CH2Ph)2(OEt)2 + 2HSeSi(SiMe3)3 f
Ti[SeSi(SiMe3)3]2(OEt)2 (7)
maroon (Zr) and bronze (Hf) colored solids. The observation
1
solution over days at room temperature but appears to decom-
pose on concentration of the reaction solution, and we have
been unable to isolate it in pure form. Interestingly, while
Ti(CH2Ph)2(OEt)2 exists as a dimer with bridging and terminal
ethoxide groups in both the solid state36 and in solution,35
variable temperature NMR studies showed a single environment
for each set of ligands down to -90 °C. These results are
consistent with the compound being monomeric, though an
oligomeric species whose bridging and terminal ligands are
exchanging rapidly on the NMR time scale cannot be ruled out.
The selenium nuclei are more shielded than in Ti[SeSi(SiMe3)3]4
(δ 416 versus δ 865 in the latter), most likely due to the higher
π-donating effect of the ethoxide groups.
Reactions of M[ESi(SiMe3)3]4 with Lewis Bases. Despite
the steric shielding of the four bulky tellurolate ligands, the
coordinatively and electronically unsaturated M[TeSi(SiMe3)3]4
compounds readily interact with small two-electron donors. For
example, Zr[TeSi(SiMe3)3]4 forms a red-brown adduct with 1,2-
dimethoxyethane (DME), as well as purple, trans L2 adducts
with PMe3 and pyridine. The six-coordinate, bis(xylylisocya-
nide) complexes M[TeSi(SiMe3)3]4(CN(xylyl))2 (M ) Zr, 70%;
M ) Hf, 49%) have been isolated and fully characterized (eq
8). Chemically equivalent tellurolate ligands suggest a trans
of two singlets for the -TeSi(SiMe3)3 ligands in both the H
and 125Te NMR spectra is consistent with a six-coordinate, η2-
DMPE complex, however, the broad linewidth of the latter
2
signals prevented the resolution of any JTeP. Singlets at δ
-2.92 (Zr) and δ -3.36 (Hf) are observed in the 31P{1H} NMR
for the chemically equivalent phosphorous nuclei.
Reaction with a second equivalent of DMPE results in the
elimination of disilyltelluride and the formation of terminal
telluride-bis(tellurolates) (eq 9) in good yields. The red-brown
compounds were isolated as crystalline solids from hexanes (Zr,
86%; Hf, 55%), with the hafnium derivative being slightly
photosensitive in solution and the solid state. As expected for
seven-coordinate species, variable temperature NMR experi-
ments showed evidence for stereochemical nonrigidity in toluene
at room temperature. At -80 °C, the terminal telluride ligands
are characterized by 125Te signals at δ -706 and δ -701 for
the zirconium and hafnium derivatives, respectively. Interest-
ingly, these values are significantly upfield from those reported
for terminal tellurides of groups 515,37 and 6.38,39 The tellurium
nuclei of the tellurolate ligands are also highly shielded (δ
-1173, -1197 for Zr; δ -1212, -1250 for Hf) relaive to the
four-coordinate homoleptics. Although the phosphorous nuclei
make up an AA′BB′ spin system, the magnetic inequivalence
is not resolved at low temperature (-80 °C) and two broad
singlets are observed in the 31P{1H} NMR spectrum of each
compound. Similarly, in the 1H NMR spectra, the DMPE
methyl and methylene hydrogens give rise to two signals each.
The crystal structures of M[TeSi(SiMe3)3]2(Te)(DMPE)2 (M
) Zr, Hf) have been determined with structural details on the
Zr derivative communicated earlier.6 Selected metrical param-
eters for the Hf compound are given in Table 3 and an ORTEP
view in Figure 3. Except for slightly shorter Hf-ligand bond
lengths, the structures are very similar. The seven-coordinate
molecules are well-approximated as pentagonal bipyramids with
the DMPE phosphorous atoms and the Te of a tellurolate in
the pentagonal belt, and the doubly bonded telluride and
remaining tellurolate coordinated at the apices. The Hf-Te-
Si angles (Hf-Te1-Si1 ) 128.26(14)°; Hf-Te2-Si5 )
142.31(16)°) are at the high end of those observed for metal
R′
N
C
RTe
M
RTe
RTe
TeR
TeR
2CNR′
(8)
M
TeR
TeR
RTe
C
N
R′
M = Zr, Hf
R = Si(SiMe3)3
R′ = xylyl
disposition of the isocyanide ligands in solution, and the
observance of a single νCN in their IR spectra (2151 and 2153
cm-1) implies a similar structure in the solid state. In all of
the base adducts, the 125Te NMR signals are shifted upfield from
their values in the homoleptic species.
(34) For a similar correlation in 13C NMR spectroscopy, see: Breitmaier,
E.; Voelter, W. Carbon-13 NMR Spectroscopy; VCH: New York,
1987, p 110.
(35) Zucchini, U.; Albizzati, E.; Giannini, U. J. Organomet. Chem. 1971,
26, 357.
(36) Stoeckli-Evans, H. HelV. Chim. Acta 1975, 58, 373.
(37) Shin, J. H.; Parkin, G. Organometallics 1994, 13, 2147.
(38) Murphy, V. J.; Parkin, G. J. Am. Chem. Soc. 1995, 117, 3522.
(39) Rabinovich, D.; Parkin, G. J. Am. Chem. Soc. 1991, 113, 9421.

2762 Inorganic Chemistry, Vol. 35, No. 10, 1996
Gerlach et al.
The increased steric demand of the -SeSi(SiMe3)3 ligand
relative to the -TeSi(SiMe3)3 ligand is evidenced by a decreased
affinity of the M[SeSi(SiMe3)3]4 compounds (M ) Ti, Zr, Hf)
toward Lewis bases. The selenolates do not form stable
complexes with 1-2 equiv of phosphines (PMe3, PMe2Ph,
PPh3), isocyanides (CN(xylyl), CN(But), pyridine, or THF.
Treatment with a large excess of Lewis base (e.g. 6 equiv of
PMe3), however, leads to elimination of Se[Si(SiMe3)3]2 and
formation of inseparable mixtures of metal-containing products.
Reaction of Zr[SeSi(SiMe3)3]4 with 1 equiv of DMPE in
hexanes or benzene resulted in the elimination of Se[Si-
(SiMe3)3]2 and the precipitation of a bright red material with
the stoichiometry Zr[SeSi(SiMe3)3]2(Se)(DMPE).42 Vibrational
bands characteristic of the -SeSi(SiMe3)3 ligand are observed
in the IR spectrum, and the compound reacts with excess H2O,
yielding HSeSi(SiMe3)3 and DMPE (2:1) (1H NMR). Although
the EI-MS shows an ion consistent with this formulation (m/z
) 974; correct isotope pattern), the presence of higher mass
peaks may be evidence for oligomeric species. Indeed, the
insolubility of the compound in common organic solvents
(which has hampered further characterization) is also consistent
with the latter suspicion. At this point we tentatively formulate
the product as an oligomer with bridging Se and/or DMPE
ligands. Hf[SeSi(SiMe3)3]4 reacts with DMPE similarly to yield
an orange product that was not investigated further.
As illustrated in eq 10, the reactions between M[SeSi-
(SiMe3)3]4 (M ) Zr, Hf) and DMPM in hexanes lead to more
tractable products. The Se- and DMPM-bridged dimers were
Figure 3. ORTEP view of the molecular structure of Hf[TeSi-
(SiMe3)3]2(Te)(DMPE)2. Methyl groups are omitted for clarity. Ther-
mal ellipsoids are plotted at the 50% probability level.
complexes of -TeSi(SiMe3)3, no doubt for the minimization
of steric interactions. The Hf-Te single bond lengths (3.019(1)
and 2.918(2) Å) are significantly longer than the Hf-Te bond
lengths in Hf[TeSi(SiMe3)3)]4, a reflection of the increase in
coordination number. In the zirconium complex, the Zr-Te
single bonds are 2.939(1) and 3.028(1) Å as compared to the
range of 2.724(1)-2.751(1) Å observed in Zr[TeSi(SiMe3)3]4.
In both molecules, it is the equitorial M-Te bond that is slightly
longer, probably due to the trans influence of the two transoid
phosphorus atoms. The longer M-Te single bonds in the seven-
coordinate species compare well with the Zr-Te bond lengths
in two independent molecules of Cp2Zr(η2-COMe)[TeSi-
(SiMe3)3] (2.990(1) and 2.996(1) Å), formally a nine-coordinate
zirconium center. In comparison, the HfdTe double bond is
2.637(2) Å, an average of 11% shorter than the Hf-Te single
bonds; a similar contraction is observed in the zirconium
complex (ZrdTe, 2.650(1) Å). These MdTe distances are
slightly shorter than those reported for CpEt*2M(Te)(NC5H5)
(M ) Zr, Hf; CpEt* ) η5-C5Me4Et) (ZrdTe, 2.729(1) Å;40
HfdTe, 2.716(1) Å 41). In both sets of compounds, the HfdTe
bond lengths are slightly shorter than the ZrdTe distances.
P
M
P
P
M
P
RSe
M
Se
Se
RSe
RSe
SeR
SeR
DMPM
–SeR2
(10)
SeR
SeR
RSe
M = Zr, Hf
R = Si(SiMe3)3
isolated in yields of 54% (Zr) and 23% (Hf) as red and orange
crystals, respectively. The 77Se NMR spectrum of the zirconium
complex exhibits a resonance at δ 69 (∆ν1/2 ) 32 Hz) for the
terminal selenolates and at δ 1390 (∆ν1/2 ) 40 Hz) for the
bridging selenides.43 The methylene hydrogens give rise to a
pentet in the 1H NMR spectrum that is indicative of a
symmetrical A-frame complex.44 A singlet with 77Se satellites
is observed in the 31P{1H} NMR spectrum at δ -23 (2JPSc
)
11 Hz). While A-frame diphosphine coordination is well-
documented for groups 5-10, we are not aware of any similarly
bridged group 4 metals. Although the products formally arise
by elimination of Se[Si(SiMe3)3]2 and dimerization of the
putative M[SeSi(SiMe3)3]2(Se)(DMPM) intermediates, the pro-
pensity of DMPM to bridge rather than chelate45 makes several
dinuclear intermediates also feasible.
The net tellurolate-to-telluride conversion is conveniently
carried out in one step and is noteworthy in two respects: (i)
the products are the only examples of a metal complex having
both singly and doubly bonded tellurium in its coordination
sphere, and (ii) the reactions may be viewed as homogenous
solution state models for a first step in a chalcogenolate-to-
chalcogenide transformation (eq 1). As observed by NMR
spectroscopy, the chelating phosphine DMPM appears to form
a similar species with the stoichiometry Zr[TeSi(SiMe3)3]2(Te)-
(DMPM)2; however, the compound is unstable with respect to
further loss of Te[Si(SiMe3)3]2, and a zirconium-containing
product could not be isolated.
An ORTEP view of {Zr[SeSi(SiMe3)3]2(µ-Se)(µ-DMPM)}2
is given in Figure 4, and selected bond distances and bond angles
are given in Table 4. The dimer lies on a crystallographic
inversion center in the middle of the Zr2Se2 core. Two terminal
-SeSi(SiMe3)3 ligands, two bridging Se atoms, and two P atoms
of the bridging DMPM ligands are coordinated to each
(42) Reactions monitored by NMR spectroscopy prior to the precipitation
of the product show significant Se[Si(SiMe3)3]2 present but also at
least three other uncharacterized products; this suggests that the
reaction may be more complicated in nature than coordination of
phosphine followed by elimination of selenoether.
(43) Due to limited solubility, only a resonance for the terminal selenolates
at -60 ppm was detected in the hafnium analogue.
(44) Jenkins, J. A.; Cowie, M. Organometallics 1992, 11, 2774.
(45) Manojlovic-Muir, L.; Muir, K. W.; Frew, A. A.; Ling, S. S. M.;
Thomson, M. A.; Puddephatt, R. J. Organometallics 1984, 3, 1637.
(40) Howard, W. A.; Parkin, G. J. Am. Chem. Soc. 1994, 116, 606.
(41) Howard, W. A.; Parkin, G. J. Organomet. Chem. 1994, 472, C1.

Homoleptic Selenolates and Tellurolates
Inorganic Chemistry, Vol. 35, No. 10, 1996 2763
Hf51), TiCl3(THF)3,52 Ti(CH2Ph)2(OEt)2,35 1,2-bis(dimethylphosphino)-
ethane (DMPE),53 (THF)2LiSeSi(SiMe3)3,7 and HESi(SiMe3)3 (E ) Se,7
Te54) were prepared by literature procedures. The diphosphine 1,2-
bis(dimethylphosphino)methane (DMPM) was purchased (Strem) and
used as received.
All NMR spectra were recorded in C6D6 at room temperature unless
otherwise noted. Chemical shifts (δ) for 1H and 13C{1H} NMR spectra
are reported relative to tetramethylsilane and were calibrated relative
to the chemical shift of the residual protium (1H) or the 13C{1H} signal
of the solvent. 31P{1H} NMR spectra were externally referenced to
85% H3PO4 in H2O. The 77Se{1H} NMR spectra were indirectly
referenced to SeMe2 at 0 ppm by direct reference to KSeCN (0.5 M in
EtOH) at -322 ppm. Chemical shifts for 125Te{1H} NMR spectra are
relative to TeMe2 at 0 ppm by reference to external 1.74 M Te(OH)6
in D2O at δ 712 ppm. Samples for IR spectroscopy were prepared as
Nujol mulls between CsI or KBr plates. Melting points were
determined in sealed capillary tubes under nitrogen and are uncorrected.
Samples for UV-vis spectroscopy were prepared as dilute hexanes
solutions (ca. 10-3 M) in quartz cells under N2. Elemental analyses
and EI-MS measurements were performed within the College of
Chemistry, University of California, Berkeley.
Figure 4. ORTEP view of the molecular structure of {Zr[SeSi-
(SiMe3)3]2(µ-Se)(µ-DMPM)}2. Methyl groups are omitted for clarity.
Thermal ellipsoids are plotted at the 50% probability level.
Table 4. Selected Metrical Parameters for {Zr[SeSi(SiMe3)3]2-
(µ-Se)(µ-DMPM)}2
Ti[SeSi(SiMe3)3]4‚HMDSO. Hexanes (45 mL) was added to a
mixture of TiCl3(THF)3 (0.361 g, 0.974 mmol) and (THF)2LiSeSi-
(SiMe3)3 (1.44 g, 3.01 mmol). The solution quickly took on a dark
orange color that gradually intensified to dark red. After 12 h, the
solvent was removed under reduced pressure and the deep red residue
was extracted into warm HMDSO (50 mL). The mixture was
concentrated and cooled to -35 °C for 12 h. The product was collected
by filtration as black crystals; 0.56 g, 39% on Ti (mp 261-263 °C
(dec)). IR: 1256 m, 1243 s, 859 s, 838 vs, 723 m, 689 m, 623 m
Bond Distances (Å)
Zr-Se1
Zr-Se2
Zr-Se3
Zr-Se3*
Zr-Zr*
2.636(2)
2.625(2)
2.598(4)
2.574(4)
3.628(3)
Zr-P1
2.749(5)
2.744(5)
2.293(5)
2.277(6)
Zr-P2
Se1-Si1
Se2-Si5
Bond Angles (deg)
Se1-Zr-Se2
Se1-Zr-Se3
Se2-Zr-Se3*
Se3-Zr-Se3*
P1-Zr-P2
92.10(7)
Zr-P1-C22
Zr-P1-C23
Zr-Se1-Si1
Zr-Se2-Si5
119.2(9)
119(1)
129.0(2)
137.9(2)
93.4(1)
84.0(1)
90.9(1)
166.9(2)
cm-1
.
1H NMR (300 MHz): δ 0.50 (s, 108H), 0.11 (s, 18H). 13C{1H}
NMR (100 MHz): δ 1.86 (s), 2.02 (s, HMDSO). 77Se{1H} NMR
(57.24 MHz): δ 865 (s). UV-vis (hexane, nm): λmax 208, 340, 498,
640. Anal. Calcd for C42H126OSe4Si18Ti: C, 33.26; H, 8.37. Found:
C, 33.38; H, 8.45.
zirconium. The average Zr-P bond distance of 2.746(7) Å is
not unusual.46 The terminal Zr-Se bonds are 2.636(2) and
2.625(2) Å, about 0.1 Å longer than in the four coordinate
homoleptic selenolate. The Zr-Zr distance is 3.628(3) Å, and
the P1-Zr-P2 angle is 166.9(2)°. Interestingly, the bulky silyl
groups of the two terminal selenolate ligands are both folded
about the zirconium in the same direction, and the tertiary silicon
atoms are nearly coplanar with both the selenium atoms and
the zirconium center (Se1-Zr-Se2-Si5 ) 2.9(3)°; Se2-Zr-
Se1-Si1 ) 178.1(2)°). Disorder involving the bridging se-
lenides (see below) precludes any meaningful discussion on the
bond lengths and bond angles of the Zr2Se2 core. The core in
Cp2Ti(µ-Se)2TiCp(Cl) is butterflied a total of 14.6°,47 while
those in [(tBuCp)2Zr(µ-E)]2 (E ) Se48, Te49,50) are planar and
nearly perfect squares.
Ti[TeSi(SiMe3)3]4. A hexanes solution (40 mL) of (THF)2LiTeSi-
(SiMe3)3 (1.83 g, 3.48 mmol) was added to a cold (-20 °C) suspension
of TiCl3(THF)3 (0.429 g, 1.16 mmol) in hexanes (20 mL). The mixture
was warmed to room temperature over 2 h and became an intense
cranberry red. The volatiles were removed under reduced pressure and
the red-purple solid was extracted into hexanes (2 × 30 mL). The
deep red filtrate was concentrated to 10 mL and cooled to -35 °C for
24 h. Black crystals were isolated by filtration; 606 mg, 34% on Ti
(mp 230-232 °C (dec.). IR: 1460 s, 1377 m, 1242 m, 837 vs, br,
729 w, br, 688 w, 621 w, 478 w cm-1
.
1H NMR (300 MHz): δ 0.54
(s). 13C{1H} NMR (100 MHz): δ 2.68 (s). 125Te{1H} NMR (157.77
MHz): δ 1302 (s). Anal. Calcd for C36H108Si16Te4Ti: C, 27.92; H,
7.03. Found: C, 27.85; H, 6.91.
Zr[SeSi(SiMe3)3]4. Method A. Hexanes (40 mL) was added to a
mixture of ZrCl4 (0.250 g, 1.07 mmol) and (THF)2LiSeSi(SiMe3)3 (2.10
g, 4.40 mmol), and the resulting light orange solution was stirred at
room temperature for 12 h, gradually darkening to orange-red. The
solvent was removed under reduced pressure and the residue extracted
into HMDSO (2 × 20 mL). Concentration of this solution followed
by cooling to -35 °C gave the product as an orange solid that was
separated by filtration (0.730 g, 49%).
Experimental Section
General. Standard inert atmosphere glovebox and Schlenk-line
techniques were employed for all manipulations. All solvents were
predried over 4 Å molecular sieves and in the case of benzene and
hexanes were distilled from sodium/benzophenone under N2, whereas
toluene and hexamethyldisiloxane (HMDSO) were distilled from
sodium. Solvents used for NMR spectroscopy were dried similarly
and then vacuum-transferred prior to use. The compounds ZrCl4 and
HfCl4 were purchased from commercial suppliers and were purified
by vacuum sublimation. The compounds M(CH2Ph)4 (M ) Ti,35 Zr,35
Method B. Hexanes (50 mL) was added to a mixture of Zr(CH2-
Ph)4 (0.584 g, 1.28 mmol) and HSeSi(SiMe3)3 (1.68 g, 5.13 mmol),
and the solution was heated to reflux for 6 h. The solvent was removed
under reduced pressure and the orange solid dissolved in HMDSO (40
mL). The solution was filtered, concentrated to 10 mL, and cooled to
-35 °C for 12 h. The product was collected by filtration as opaque,
orange crystals; 1.32 g, 74% (mp 268-269 °C (dec.), black). IR: 1258
m, 1243 s, 861 s, 838 vs, 688 m 622 m cm-1
.
1H NMR (300 MHz):
δ 0.48 (s). 13C{1H} NMR (100 MHz): δ 1.50 (s). 77Se{1H} NMR
(46) Girolami, G. S.; Wilkinson, G. J. Chem. Soc., Dalton Trans. 1984,
2789.
(47) Fenske, D.; Maue, P. G. Z. Naturforsch. 1988, 43b, 1213.
(48) Tainturier, G.; Fahim, M.; Gautheron, B. J. Organomet. Chem. 1989,
311.
(49) Erker, G.; Muhlenbernd, T.; Nolte, R.; Petersen, J. L.; Tainturier, G.;
Gautheron, B. J. Organomet. Chem. 1986, 314, C21.
(50) Erker, G.; Nolte, R.; Tainturier, G.; Rheingold, A. Organometallics
1989, 8, 454.
(51) Felten, J. J.; Anderson, W. P. J. Organomet. Chem. 1972, 36, 87.
(52) Manzer, L. E.; Deaton, J.; Sharp, P.; Schrock, R. R. Inorg. Synth.
1982, 21, 137.
(53) Burt, R. J.; Chatt, J.; Hussain, W.; Leigh, G. J. J. Organomet. Chem.
1979, 182, 203.
(54) Dabbousi, B. O.; Bonasia, P. J.; Arnold, J. J. Am. Chem. Soc. 1991,
113, 3186.

2764 Inorganic Chemistry, Vol. 35, No. 10, 1996
Gerlach et al.
(57.24 MHz): δ 356 (s). UV-vis (nm): λmax 216, 286, 346, 458.
Anal. Calcd for C36H108Se4Si16Zr: C, 30.94; H, 7.79. Found: C, 30.99;
H, 7.56.
(dec.), orange-red oil). IR: 1258 w, 1244 m, 862 m, 837 s, 741 w,
723 w, 691 w, 622 w cm-1 1H NMR (300 MHz): δ 0.41 (s, 81H,
.
SiMe3), 2.69 (s, 2H, CH2Ph), 6.92 (t, 1H, p-Ph, 7 Hz), 7.25 (t, 3H,
m-Ph, 8 Hz), 7.50 (d, 2H, o-Ph, 6 Hz). 13C{1H} NMR (100 MHz): δ
1.30 (s, SiMe3), 97.54 (s, CH2Ph), 142.12, 130.33, 128.89, 123.57 (s,
Ph). 77Se{1H} NMR (57.24 MHz): δ 206 (s). Uv-vis (nm): λmax
214, 246, 304. Anal. Calcd for C34H88HfSe3Si16: C, 32.68; H, 7.10.
Found: C, 32.31; H, 7.37.
Zr[TeSi(SiMe3)3]4. A hexanes solution (50 mL) of HTeSi(SiMe3)3
(4.95 g, 13.2 mmol) was added to a cold (-20 °C) suspension of
Zr(CH2Ph)4 (1.50 g, 3.29 mmol) in hexanes (50 mL). The mixture
was warmed to room temperature and stirred for 4 h. The solvent was
removed under reduced pressure, and the green, microcrystalline solid
was recrystallized from hexanes affording the product in two crops;
4.05 g, 77% (mp 227-230 °C (dec.), black). IR: 1256 sh, 1243 s,
Zr[TeSi(SiMe3)3]4(CN(xylyl))2. A hexanes solution (30 mL) of
xylyl isocyanide (155 mg, 1.18 mmol) was added to a hexanes solution
(30 mL) of Zr[TeSi(SiMe3)3]4 (0.94 g, 59 mmol). The gree mixture
immediately became intensely purple. After stirring for 0.5 h, the
volatiles were removed under reduced pressure and the solid extracted
into and recrystallized from hexanes at -35 °C. The product was
isolated in two crops by filtration as a maroon, microcrystalline solid;
0.77 g, 70% (mp 145-148 °C (dec.)). IR: 2151 (νCN), 1236 w, 835
837 vs, br, 744 w, 688 m, 622 m cm-1 1H NMR (400 MHz): δ 0.51
.
(s). 13C{1H} NMR (100 MHz): δ 2.39 (s). 125Te{1H} NMR (157.77
MHz): δ 459 (s). EI-MS: 1592 (M+), 1344, 1215, 895, 752, 679,
623. Anal. Calcd for C36H108Si16Te4Zr: C, 27.16; H, 6.84. Found:
C, 26.96; H, 6.75.
Hf[SeSi(SiMe3)3]4. This preparation was analogous to that used to
synthesize the zirconium complex by method A; 0.67 g, 48% (mp 262-
264 °C (dec.), black). IR: 1258 m, 1244 m, 861 m, 838 s, 688 m, 622
s, br, 771 w, 689 w, 620 w cm-1 1H NMR (400 MHz): δ 0.48 (s,
.
108H, SiMe3), 2.70 (s, 12H, xylyl-Me), 6.77 (d, 4H, m-Ph), 6.89 (t,
2H, p-Ph). 13C{1H} NMR (100 MHz, C7D8): δ 3.00 (s, SiMe3), 20.01
(s, xylyl-Me), 135.26, 129.76, 128.31, 127.09 (s, Ph), 173.5 (s, xylyl-
NC). 125Te{1H} NMR (157.77 MHz, C7D8): δ 203 (s). EI-MS: 1592
(M+ - 2C6H3Me2NC), 1346, 1216. Anal. Calcd for C54H126N2Si16-
Te4Zr: C, 35.0; H, 6.85; N, 1.51. Found: C, 35.3; H, 6.65; N, 1.52.
Hf[TeSi(SiMe3)3]4(CN(xylyl))2. This preparation was analogous
with that used for the zirconium analogue except the reaction was stirred
for 10 h; 0.43 g, 49% (dark red, (mp 157-163 °C (dec.)). IR: 2153
(νCN), 1240 s, 1174 w, 1092 w, 1034 w, 860 sh, 837 vs, br, 775 m,
m cm-1
.
1H NMR (400 MHz): δ 0.49 (s). 13C{1H} NMR (100
MHz): δ 1.55 (s). 77Se{1H} NMR (57.24 MHz): δ 211 (s). UV-vis
(nm): λmax 216, 280 sh, 406. Anal. Calcd for C36H108HfSe4Si16: C,
29.12; H, 7.33. Found: C, 29.46; H, 7.18.
Hf[TeSi(SiMe3)3]4. This preparation was analogous to that used
for the zirconium complex; 0.40 g, 79% (mp 225-230 °C (dec.)). IR:
1257 w, 1243 s, 858 sh, 836 vs, br, 688 m, 622 m cm-1 1H NMR
.
(400 MHz): δ 0.51 (s). 13C{1H} NMR (100 MHz): δ 2.50 (s).
125Te{1H} NMR (157.77 MHz): δ 193 (s). EI-MS: 1680 (M+), 1433,
1303, 982, 927, 623. Anal. Calcd for C36H108Si16Te4Hf: C, 25.79; H,
6.48. Found: C, 25.39; H, 6.49.
688 m, 624 m cm-1 1H NMR (400 MHz): δ 0.50 (s, 108H, SiMe3),
.
2.72 (s, 12H, xylyl-Me), 6.75 (d, 4H, m-Ph), 6.88 (t, 2H, p-Ph). 13C{1H}
NMR (100 MHz, C7D8): δ 3.04 (s, SiMe3), 20.01 (s, xylyl-Me), 135.33,
129.81, 128.34, 126.96 (s, Ph), 178.5 (s, xylyl-NC). 125Te{1H} NMR
Generation of Ti[SeSi(SiMe3)3]2(OEt)2. A C7D8 solution (0.5 mL)
containing 31.2 mg (0.0974 mmol) of Ti(CH2Ph)2(OEt)2 and 63.8 mg
(0.195 mmol) of HSeSi(SiMe3)3 was prepared and loaded into a NMR
tube fitted with a sealable Teflon cap. The clear orange solution was
heated to 50 °C for 14 h and became a cherry red color. Analysis of
the sample by NMR spectroscopy indicated the formation of toluene
and Ti[SeSi(SiMe3)3]2(OEt)2; 95%. 1H NMR (300 MHz): δ 0.40 (s,
54H, SiMe3), 1.23 (t, 6H, OCh2CH3, 7 Hz), 4.34 (q, 4H, OCH2CH3, 7
Hz). 13C{1H} NMR (100 MHz): δ 1.10 (s, SiMe3), 21.4 (s, OCH2CH3),
76.1 (s, CH2CH3). 77Se{1H} NMR (57.24 MHz): δ 416 (s).
(157.77 MHz, C7D8): δ -14 (s). Anal. Calcd for C54H126
-
HfN2Si16Te4: C, 33.4; H, 6.54; N, 1.44. Found: C, 31.6; H, 6.46; N,
1.39.
Zr[TeSi(SiMe3)3]4(DMPE). DMPE (105 µL, 0.628 mmol) was
added to a hexanes solution (50 mL) of Zr[TeSi(SiMe3)3]4 (1.00 g,
0.628 mmol). The red-purple mixture was stirred for 8 h. Concentra-
tion and cooling of the mother liquor to -78 °C afforded the maroon
product that was isolated by filtration; 0.62 g, 57% (mp 176-178 °C
(dec.)). IR: 1242 s, 947 w, 929 w, 858 sh, 835 s, br, 722 w, 688 w,
Ti[SeSi(SiMe3)3]3(CH2Ph). A hexanes solution (15 mL) of HSeSi-
(SiMe3)3 (1.27 g, 3.88 mmol) was added to a cold (-5 °C) suspension
of Ti(CH2Ph)4 (0.535 g, 1.30 mmol) in hexanes (40 mL). The mixture
was warmed to room temperature and stirred for 1 h during which time
it became increasingly red. The solvent was removed under reduced
pressure and the red precipitate extracted into HMDSO (35 mL).
Concentration and cooling of this solution afforded the product in two
crops as a rust colored, microcrystalline solid; 0.86 g, 59% (mp 174-
176 °C (dec.), black). IR: 1256 w, 1243 m, 859 m, 835s, 740 w, 722
624 w cm-1 1H NMR (400 MHz): δ 0.48 (s, 54H, SiMe3), 0.62 (s,
.
54H, SiMe3), 1.63 (m, 4H, PCH2), 1.76 (m, 12H, PMe). 13C{1H} NMR
(100 MHz, C7D8): δ 3.59 (s, SiMe3), 3.63 (s, SiMe3), 22.33 (m, PCH3),
27.90 (m, PCH2). 31P{1H} NMR (162.92 MHz, C7D8): δ -2.92 (s).
125Te{1H} NMR (157.77 MHz, C7D8): δ 151 (s), -116 (s).
Hf[TeSi(SiMe3)3]4(DMPE). This preparation was analogous with
that used for the zirconium analogue; 250 mg, 46% (bronze colored).
1H NMR (400 MHz): δ 0.48 (s, 54H, SiMe3), 0.60 (s, 54H, SiMe3),
1.68 (m, 4H, PCH2), 1.81 (m, 12H, PMe). 13C{1H} NMR (100 MHz,
C7D8): δ 2.40 (s, SiMe3), 3.67 (s, SiMe3), 22.38 (m, PCH3), 27.94 (m,
PCH2). 31P{1H} NMR (161.92 MHz, C7D8): δ -3.36 (s). 125Te{1H}
NMR (157.77 MHz, C7D8): δ 128 (s), -349 (s). The extreme solubility
of both the zirconium and hafnium mono(DPME) adducts in hexane,
pentane, and hexamethyldisiloxane prevented purification to >95%.
Characterization rests upon NMR data and the smooth conversion to
the bis(DMPE) tellurides upon addition of 1 equiv of DMPE.
w, 689 w cm-1
.
1H NMR (400 MHz): δ 0.44 (s, 81H, SiMe3), 3.58
(s, 2H, CH2Ph), 6.85 (t, 1H, p-Ph, 7 Hz), 7.22 (t, H, m-Ph, 8 Hz), 7.56
(d, 2H, o-Ph, 7 Hz). 13C{1H} NMR (100 MHz): δ 1.46 (s, SiMe3),
109.56 (s, CH2Ph), 148.50, 130.12, 128.37, 123.24 (s, Ph). 77Se{1H}
NMR (57.24 MHz): δ 828 (s). Uv-vis (nm): λmax 208, 250, 320,
430. Anal. Calcd for C34H88Se3Si16Ti: C, 36.5; H, 7.93. Found: C,
36.2; H, 8.19.
Zr[SeSi(SiMe3)3]3(CH2Ph). This preparation was analogous with
that used to synthesize the titanium derivative; 1.6 g, 54% (mp 172-
174 °C (dec.), black). The bright orange product obtained is usually
contaminated with ca. 5% of Zr[SeSi(SiMe3)3]4 (1H NMR). Attempts
to purify the compound further were unsuccessful (mp 172-174 °C
(dec.)). IR: 1257 w, 1242 m, 860 m, 838 s, 740 w, 723 w, 691 w,
Zr[TeSi(SiMe3)3]2(Te)(DMPE)2. DMPE (0.36 mL, 4.38 mmol) was
added to a hexanes solution (30 mL) of Zr[TeSi(SiMe3)3]4 (3.49 g,
2.19 mmol). The initially green solution changed to purple and then
to brown. The mixture was stirred for 0.5 h, concentrated, and then
cooled to -35 °C. Red-brown crystals were separated from the mother
liquor by filtration; 2.39g, 86% (mp 128-130 °C (dec.)). IR: 1239
m, 945 m, 930 m, 890 w, 835 vs, br, 727 w, 686 w, 647 w, 623 w
622 w cm-1 1H NMR (400 MHz): δ 0.41 (s, 81H, SiMe3), 3.10 (s,
.
2H, CH2Ph), 7.08 (t, 1H, p-Ph, 6 Hz), 7.22 (t, 3H, m-Ph, 6 Hz), 7.33
(d, 2H, o-Ph, 6 Hz). 13C{1H} NMR (100 MHz): δ 1.40 (s, SiMe3),
83.12 (s, CH2Ph), 137.43, 131.21, 130.82, 125.68 (s, Ph). 77Se{1H}
NMR (57.24 MHz): δ 338 (s). Uv-vis (nm): λmax 210, 262, 336.
Hf[SeSi(SiMe3)3]3(CH2Ph). A hexanes solution (15 mL) of HSeSi-
(SiMe3)3 (2.55 g, 7.78 mmol) was added dropwise over 10 min to a
stirred hexanes solution (50 mL) of Hf(CH2Ph)4 (1.41 g, 2.60 mmol).
The mixture gradually became pale, yellow-green. After 1 h, the
solvent was removed under reduced pressure, leaving the product as a
pastel yellow, microcrystalline solid; 3.02 g, 93% (mp 172-178 °C
cm-1
.
1H NMR (400 MHz, C7D8, -78 °C): δ 0.32 (s, 27H, SiMe3),
0.58 (s, 27H, SiMe3), 1.24 (m, 12H, PMe), 1.58 (m, 12H, PMe), 2.05
(m, 4H, PCH2), 2.19 (m, 4H, PCH2). 31P{1H} NMR (161.92 MHz,
C7D8, -80 °C): δ 1.28 (s, 2JPTe ) 74 Hz), -3.22 (s, 2JPTe ) 168 Hz).
125Te{1H} NMR (157.77 MHz, C7D8, -78 °C): δ -706 (s), -1173 (t,
2JTeP ) 166 Hz), -1197 (s). Anal. Calcd for C30H86P4Si8Te3Zr: C,
32.6; H, 6.96. Found: C, 32.8; H, 6.97.
Hf[TeSi(SiMe3)3]2(Te)(DMPE)2. This preparation was analogous
to that used to synthesize the zirconium analogue; 222 mg, 55% (red-

Homoleptic Selenolates and Tellurolates
Inorganic Chemistry, Vol. 35, No. 10, 1996 2765
Table 5. Summary of X-ray Diffraction Data
Zr[SeSi(SiMe3)3]4
Hf[TeSi(SiMe3)3]4
Hf[TeSi(SiMe3)3]2(Te)(DMPE)2 {Zr[SeSi(SiMe3)3]2(Se)(DMPM)}2
formula
MW
space group
a (Å)
b (Å)
c (Å)
C36H108Se4Si16Zr
1397.68
P21/c
22.6944(34)
15.2943(55)
22.7758(61)
90
105.695(17)
90
7611(4)
4
C36H108HfSi16Te4
1679.53
P21/c
22.494(5)
15.609(5)
22.742(5)
90
104.480(5)
90
7731
C30H86HfP4Si8Te3
1356.89
P21
14.795(3)
14.289(3)
15.4212(2)
90
102.543(3)
90
3182(1)
2
C46H136P4Se6Si16Zr2
1919.05
P21/n
14.7651(13)
18.8579(17)
18.6072(17)
90
111.031(1)
90
R (deg)
â (deg)
γ (deg)
vol (Å3)
Z
4836(1)
2
1.32
4
d
calcd (g cm-3
)
1.22
1.443
1.416
cryst size (mm)
radiation (λ/Å)
scan mode
2θ range (deg)
collcn range
0.50 × 0.50 × 0.40 0.20 × 0.15 × 0.10
0.30 × 0.20 × 0.10
Mo KR (0.7103)
θ-2θ
0.18 × 0.13 × 0.04
Mo KR (0.7103)
ω (0.3 deg scans)
4-46.5
Mo KR (0.7103)
θ-2θ
Mo KR (0.7103)
θ-2θ
3-45
+h, +k, (l
23.31
3-45
+h, +k, (l
30.9
3-45
+h, +k, (l
32.4
4354
3403
0.0478, 0.0670
-105
hemisphere
27.6
absorption coeff, µ (cm-1
no. of unique reflcns
reflcns with F2 > 3σ(F2)
final R,Rw
)
10402
5300
10082
7019
6969
3480
0.0826, 0.0813
-94
0.0529, 0.0369
-85
0.0448, 0.0545
-93
T (°C)
brown). 1H NMR (400 MHz, C7D8, -78 °C): δ 0.36 (s, 27H, SiMe3),
0.64 (s, 27H, SiMe3), 1.36 (m, 12H, PMe3), 1.64 (m, 12H, PMe3), 2.05
(m, 4H, PCH2), 2.12 (m, 4H, PCH2). 31P{1H} NMR (161.92 MHz,
-78 °C): δ -1.39 (s, br), -10.67 (s, br). 125Te{1H} NMR (157.77
MHz, C7D8, -78 °C): δ -701 (s), -1212 (t, 2JTeP ) 190 Hz), -1250
(s).
{Zr[SeSi(SiMe3)3]2(Se)(DMPE)}n. DMPE (15 µL, 0.090 mmol)
was added to a hexanes solution (10 mL) of Zr[SeSi(SiMe3)3]4 (114
mg, 0.0816 mmol). The solution was thoroughly mixed and allowed
to remain undisturbed at room temperature. After 24 h, red crystals
were isolated by filtration; 0.49 mg, 62% (mp 185-186 °C (dec.),
black). IR: 1295 w, 1280 w, 1257 w, 1240 m, 946 m, 935 m, 920 w
sh, 896 w, 863 s, 835 vs, 687 m, 649 w, 626 m, 462 w cm-1. EI-MS:
974 (M+ for monomer). Anal. Calcd for C24H70Se3Si8P2Zr: C, 30.07;
H, 6.74. Found: C, 29.84; H, 6.94.
CAD4 diffractometer, and centered in a steam of cold dinitrogen gas.
Cell constants and orientation matrix were obtained from the least
squares refinement of 25 carefully centered high-angle reflections. The
intensities of three standard reflections were measured every 200
reflections, and no crystal decay was observed over the course of the
experiment. The data were corrected for Lorentz and polarization
effects. An empirical absorption correction based on azimuthal scans
near ø ) 90° was applied to the data. Inspection of the systematic
absences uniquely defined the space group P21/c. The structure was
solved by direct methods using the TEXSAN package55 on a Digital
VAX station and refined using standard least squares and Fourier
techniques. The silicons Si14-Si16 (attached to Si13) were each
disordered about two sites and were modeled by assinging them
occupancies of 0.5. Two of the carbons for each disordered -SiMe3
were in the same position, and the remaining carbon atoms were given
occupancies of 0.5. The partial occupancy atoms refined successfully
with isotropic thermal parameters. All of the other non-hydrogen atoms
were refined with anisotropic thermal parameters. All of the hydrogen
atoms except those associated with the disordered -Si(SiMe3)3 were
introduced at idealized positions and included in structure factor
calculations but not refined. Neutral atomic scattering factors were
taken from Cromer and Waber,56 and anomalous dispersion effects were
included in Fc.57 The final residuals for 508 variables refined against
5300 data for which F2 > 3σ(F2) were R ) 0.0529, Rw ) 0.0369, and
GOF ) 2.16.
{Zr[SeSi(SiMe3)3]2(µ-Se)(µ-DMPM)}2. A hexanes solution (20
mL) of Zr[SeSi(SiMe3)3]4 (331 mg, 0.224 mmol) was treated with
DMPM (35 µL, 0.22 mmol) and the mixture stirred for 24 h, becoming
increasingly red. The solvent was removed under reduced pressure
and the red-orange residue extracted with hexanes (2 × 15 mL).
Concentration of the red filtrate and cooling to -35 °C afforded the
product as red crystals that were isolated by filtration; 105 mg, 54%
(mp 175-180 °C (dec.), black). IR: 1297 w, 1283 w, 1256 w, 1239
m, 946 m, 933 m, 893 m, 860 m, 834 s, 686 m, 622 m cm-1
.
1H
NMR (400 MHz, C7D8): δ 0.47 (s, 54H, SiMe3), 1.56 (s, 12H, PMe),
1.91 (pentet, 2H, PCH2, JHP ) 5 Hz). 13C{1H} NMR (100 MHz,
C7D8): δ 2.28 (s, SiMe3), 18.5 (m, PMe). 31P{1H} NMR (161.92 MHz,
C7D8): δ -23.3 (s, JPSe ) 11 Hz). 77Se{1H} NMR (57.24 MHz,
Hf[TeSi(SiMe3)3]4. Crystals were grown from hexanes at -35 °C.
Unit cell parameters, orientation matrix, and diffraction data were
collected with an Enraf-Nonius CAD-4-diffractometer as above. The
structure was solved by direct methods (SHELXS) and refined via
standard least squares and Fourier techniques.58,59 All non-hydrogen
atoms were refined with anisotropic thermal parameters. Hydrogen
atoms were treated as above. The final residuals for 515 variables
refined against 7019 data for which F2 > 3σ(F2) were R ) 0.0448, Rw
) 0.0545, and GOF ) 1.31.
C7D8): δ 63 (s, ∆ν1/2 ) 32 Hz, terminal selenolate), 1390 (s, ∆ν1/2
)
40 Hz, µ-Se). Anal. Calcd for C46H136P4Se6Si16Zr2: C, 28.79; H, 7.14.
Found: C, 28.53; H, 7.29.
{Hf[SeSi(SiMe3)3]2(µ-Se)(µ-DMPM)}2. This preparation was analo-
gous with that used to prepare the analogous zirconium derivative except
the reaction was stirred a total of 48 h; 80 mg, 23% (mp 200-215 °C
(dec.), orange > red > black). 1H NMR (300 MHz): δ 0.50 (s, 54H,
SiMe3), 1.65 (s, 12H, PMe), 2.06 (pentet, 2H, PCH2, JHP ) 5 Hz).
13C{1H} NMR (100 MHz): δ 2.39 (s, SiMe3), 18.6 (m, PMe). 31P-
{1H} NMR (162 MHz): δ -20.7 (s, 2JPSe ) 13 Hz). 77Se NMR (57.2
MHz, C7D8): δ -60 (s, terminal selenolate, ∆ν1/2 ) 30 Hz). Due to
limited solubility (ca. 10 mg‚mL-1), a resonance for the µ-Se could
not be detected. Anal. Calcd for C46H136Hf2P4Se6Si16: C, 26.39; H,
6.55. Found: C, 26.14; H, 6.79.
Hf[TeSi(SiMe3)3]2(Te)(DMPE)2. Crystals were grown from pentane
at -35 °C. Diffraction data were collected as described above. The
(55) TEXSAN: Crystal Structure Analysis Package; Molecular Structure
Corp.: 1992.
(56) Cromer, D. T.; Waber, J. T. International Tables for X-ray Crystal-
lography; The Kynoch Press: Birmingham, England, 1974; Vol. IV,
Table 2.2B.
(57) Cromer, D. T.; Waber, J. T. International Tables for X-ray Crystal-
lography; The Kynoch Press: Birmingham, England, 1974; Vol. IV,
Table 2.3.1.
(58) Calculations were performed on a DEC Microvax II using locally
modified versions of the Enraf-Nonius MolEN structure solution and
refinement package and other programs.
X-ray Crystallography. A summary of the data collection param-
eters and structural refinement for all crystallographically characterized
compounds is given in Table 5.
Zr[SeSi(SiMe3)3]4. Suitable crystals were grown by slowly cooling
a saturated hexanes solution of the compound to -35 °C. The crystal
was mounted on a glass capillary with Paratone-N oil, transferred to a
(59) MolEn; Delft Instruments: Delft, The Netherlands, 1990.

2766 Inorganic Chemistry, Vol. 35, No. 10, 1996
Gerlach et al.
structure was solved by direct methods (SHELXS) and refined as above.
An empirical absorption correction was applied using DIFABS.60-62
A carbon atom on a -SiMe3 was disordered about two sites and
modeled successfully with two partial occupancy carbon atoms (C21,
0.65 occ; C21′, 0.35 occ). All carbon atoms were refined with isotropic
thermal parameters and all remaining heavy atoms with anisotropic
thermal parameters. The final residuals for 268 variables refined against
3403 data for which F2 > 3σ(F2) were R ) 0.0478, Rw ) 0.0670, and
GOF ) 2.75.
{Zr[SeSi(SiMe3)3]2(µ-Se)(µ-DMPM)}2. A suitable crystal was
grown from a concentrated hexanes solution at -35 °C. Data collection
was conducted with a Siemens SMART diffractometer/CCD area
detector.63 A preliminary orientation matrix and unit cell parameters
were determined by collecting 60 10-s frames, followed by spot
integration and least squares refinement. A hemisphere of data was
collected using 30-s scans per frame. The raw data were integrated
(XY spot spread ) 1.60°; Z spot spread ) 0.60°) and the unit cell
parameters refined (3290 reflections with I > 10σ) using SAINT.64
Preliminary data analysis and an absorption correction (Tmin ) 0.521;
Tmax ) 0.887) were performed using XPREP.65 Of the 11564 reflections
measured, 6969 were independent and the redundant reflections were
averaged with an 8.42% internal consistency. No correction for crystal
decay was applied. The structure was solved and refined as for Zr-
[SeSi(SiMe3)3]4. The molecule lies on a crystallographic inversion
center in the center of the Zr2Se2 core. Three carbon atoms of the
peripheral -SiMe3 groups were disordered about two sites and were
modeled as six carbons with occupancies of 0.5. The methylene bridge
of the DMPM, the pair of methyl carbons off P2, and the bridging Se
atoms were similarly disordered and modeled analogously. All partial
occupancy atoms refined successfully with isotropic thermal parameters.
Methyl hydrogens were introduced at fixed positions for all full
occupancy carbons and treated as above. The final residuals for 327
variables refined against 3480 data for which F2 > 3σ(F2) were R )
0.0826, Rw ) 0.0813, and GOF ) 2.55.
Acknowledgment. We are grateful to the National Science
Foundation for financial support, the Alfred P. Sloan Foundation
for the award of a research fellowship to J.A., and to E. K.
Brady for preliminary experiments.
Supporting Information Available: ORTEP diagrams showing
complete numbering schemes and listings of bond distances and angles
and positional and thermal parameters, for Hf[TeSi(SiMe3)3]4, Zr[SeSi-
(SiMe3)3]4, Hf[TeSi(SiMe3)3]2(Te)(DMPE)2, and {Zr[SeSi(SiMe3)3]2-
(µ-Se)(µ-η2-DMPM)2}2 (25 pages). Ordering information is given on
any current masthead page.
(60) Katayama, C.; Sakabe, N.; Sakabe, K. Acta Crystallogr. 1972, A39,
158.
(61) Ugozzli, F. Comput. Chem. 1987, 11, 109.
(62) Katayama, C. Acta Crystallogr. 1986, A42, 19.
(63) SMART Area-Detector Software Package; Siemens Industrial Automa-
tion, Inc.: Madison, WI, 1993.
IC9600689
(64) SAINT: SAX Area-Detector Integration Program, v. 4.024; Siemens
Industrial Automation, Inc.: Madison, WI, 1994.
(65) XPREP: Part of the SHELXTL Crystal Structure Determination
Package; Siemens Industrial Automation: Madison, WI, 1994.