Tris[(alkylthio)methyl]silanes: Syntheses and structures of chromium, molybdenum, and tungsten complexes with a tripodal thioether ligand

Article abstract of DOI:10.1021/ic981001j

The first member of a new family of tripodal thioether ligands, the methyltris[(alkylthio)methyl]silanes MeSi-(CH₂SR)₃ (R = Me), has been synthesized and characterized. Reactivity studies lead to the isolation of the complete series of group 6 metal carbonyl derivatives {η³-MeSi(CH₂SMe)₃}M(CO)₃ (M = Cr, Mo, W), whose structures have been determined by single-crystal X-ray diffraction. The three complexes are isomorphous and display distorted octahedral structures with face-capping tridentate thioether ligands. {η³-MeSi(CH₂SMe)₃}Cr(CO)₃ is monoclinic, P2₁/c, a = 8.1658(2) A?, b = 15.0563(2) A?, c = 26.5791(3) A?, β= 90.3653(6)°, V = 3267.74(8) A?³, Z = 8. {η³-MeSi(CH₂SMe)₃}Mo(CO)₃ is monoclinic, P2₁/c, a = 8.34630(6) A, b = 15.2747(2) A?, c = 27.1865(4) A?, β = 90.8987(9)°, V= 3465.44(10) A?³, Z = 8. {η³-MeSi(CH₂SMe)₃}W(CO)₃ is monoclinic, P2₁/c, a = 8.1582(2) A?, b = 14.9903(2) A?, c = 26.7268(4) A?, β = 90.6568(8)°, V = 3268.30(9) A?³, Z = 8.

Full text of DOI:10.1021/ic981001j

Inorg. Chem. 1999, 38, 2211-2215
2211
Tris[(alkylthio)methyl]silanes: Syntheses and Structures of Chromium, Molybdenum, and
Tungsten Complexes with a Tripodal Thioether Ligand
Hing W. Yim, Linh M. Tran, Ebern D. Dobbin, and Daniel Rabinovich*
Department of Chemistry, The University of North Carolina at Charlotte,
9
201 University City Boulevard, Charlotte, North Carolina 28223
Louise M. Liable-Sands, Christopher D. Incarvito, Kin-Chung Lam, and
Arnold L. Rheingold*
Department of Chemistry and Biochemistry, The University of Delaware, Newark, Delaware 19716
ReceiVed August 19, 1998
The first member of a new family of tripodal thioether ligands, the methyltris[(alkylthio)methyl]silanes MeSi-
(
CH2SR)3 (R ) Me), has been synthesized and characterized. Reactivity studies lead to the isolation of the complete
3
series of group 6 metal carbonyl derivatives {η -MeSi(CH2SMe)3}M(CO)3 (M ) Cr, Mo, W), whose structures
have been determined by single-crystal X-ray diffraction. The three complexes are isomorphous and display distorted
octahedral structures with face-capping tridentate thioether ligands. {η -MeSi(CH2SMe)3}Cr(CO)3 is monoclinic,
P21/c, a ) 8.1658(2) Å, b ) 15.0563(2) Å, c ) 26.5791(3) Å, â ) 90.3653(6)°, V ) 3267.74(8) Å , Z ) 8.
{
â ) 90.8987(9)°, V ) 3465.44(10) Å , Z ) 8. {η -MeSi(CH2SMe)3}W(CO)3 is monoclinic, P21/c, a ) 8.1582(2)
Å, b ) 14.9903(2) Å, c ) 26.7268(4) Å, â ) 90.6568(8)°, V ) 3268.30(9) Å , Z ) 8.
3
3
3
η -MeSi(CH2SMe)3}Mo(CO)3 is monoclinic, P21/c, a ) 8.34630(6) Å, b ) 15.2747(2) Å, c ) 27.1865(4) Å,
3
3
3
Introduction
Chart 1. Tridentate Thioether Ligands
The coordination chemistry of simple monodentate (RSR′)
1
and bidentate [RS(CH2)nSR′] thioethers is well-established.
Interest in polythioethers, the best known of which are macro-
2
cyclic species such as 1,4,7-trithiacyclononane (Chart 1A), has
increased substantially in recent years in view of their unique
structural and electronic properties. Although a number of
tridentate sulfide ligands other than crown thioethers are known,
analogues of Riordan’s anionic poly[(alkylthio)methyl)]borates
3
4
5
including MeC(CH2SEt)3, RS(CH2)2S(CH2)2SR (R ) Me, Et ),
8
(Chart 1C). In addition, the ease with which the Si-Cl bonds
6
7
1
,3,5-(MeS)3C6H9, and C6H6S3, reactivity studies with them
in chlorosilanes (e.g., MeSiCl3) undergo nucleophilic substitution
may be advantageously used to produce the silanes in good
yields. We have recently applied this strategy to prepare the
are scant. With the aim of embarking on a systematic study of
new trithioether ligands, we envisioned the syntheses of the
methyltris[(alkylthio)methyl]silanes MeSi(CH2SR)3 (Chart 1B),
expecting that distinctive steric and electronic effects could be
attained by varying the terminal substituents (R) in the thioether
arms. In support of this belief, the proposed ligands share this
structural feature with and could be considered neutral isosteric
methyltris(pyrazolyl)silane nitrogen donors MeSi(3,5-RR′pz)3
t
(
R ) R′ ) Me; R ) Bu , R′ ) H) almost quantitatively from
9
MeSiCl3 and the corresponding lithium pyrazolates. The
synthesis and characterization of the (methylthio)methyl deriva-
tive MeSi(CH2SMe)3 and the preparation of its first transition
metal complexes are described in this paper.
(
1) (a) Murray, S. G.; Hartley, F. R. Chem. ReV. 1981, 81, 365-414. (b)
M u¨ ller, A.; Diemann, E. In ComprehensiVe Coordination Chemistry;
Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.; Pergamon
Press: New York, 1987; Vol. 2, Chapter 16.2, pp 551-558.
Results and Discussion
Synthesis and Characterization of MeSi(CH2SMe)3. The
tripodal thioether methyltris[(methylthio)methyl]silane was readily
synthesized by allowing a pentane solution of methyltrichlo-
(
(
(
2) (a) Cooper, S. R.; Rawle, S. C. Struct. Bonding 1990, 72, 1-72. (b)
Blake, A. J.; Schr o¨ der, M. AdV. Inorg. Chem. 1990, 35, 1-80.
3) Chatt, J.; Leigh, G. J.; Storace, A. P. J. Chem. Soc. A 1971, 1380-
1389.
10
rosilane to react with 3 equiv of LiCH2SMe (eq 1). The latter
4) (a) Ashby, M. T.; Enemark, J. H.; Lichtenberger, D. L.; Ortega, R. B.
Inorg. Chem. 1986, 25, 3154-3157. (b) Baker, P. K.; Harris, S. D.;
Durrant, M. C.; Hughes, D. L.; Richards, R. L. J. Chem. Soc., Dalton
Trans. 1994, 1401-1407.
was generated in situ by deprotonation of dimethyl sulfide with
(8) (a) Ge, P.; Haggerty, B. S.; Rheingold, A. L.; Riordan, C. G. J. Am.
Chem. Soc. 1994, 116, 8406-8407. (b) Ohrenberg, C.; Ge, P.;
Schebler, P.; Riordan, C. G.; Yap, G. P. A.; Rheingold, A. L. Inorg.
Chem. 1996, 35, 749-754. (c) Schebler, P. J.; Riordan, C. G.; Guzei,
I. A.; Rheingold, A. L. Inorg. Chem. 1998, 37, 4754-4755.
(9) Pullen, E. E.; Rheingold, A. L.; Rabinovich, D. Inorg. Chem. Commun.,
in press.
(
(
(
5) Mannerskantz, H. C. E.; Wilkinson, G. J. Chem. Soc. 1962, 4454-
4458.
6) Amundsen, A. R.; Whelan, J.; Bosnich, B. J. Am. Chem. Soc. 1977,
9, 6730-6739.
7) Grant, G. J.; Grant, C. D.; Setzer, W. N. Inorg. Chem. 1991, 30, 353-
55.
9
3
1
0.1021/ic981001j CCC: $18.00 © 1999 American Chemical Society
Published on Web 04/15/1999

2212 Inorganic Chemistry, Vol. 38, No. 9, 1999
Yim et al.
pentane
MeSiCl + 3LiCH SMe
8 MeSi(CH SMe) (1)
3
2
2 3
-3LiCl
n-butyllithium in the presence of N,N,N′,N′-tetramethylethyl-
enediamine (TMEDA).11 MeSi(CH2SMe)3 was isolated as a
colorless (or more often pale yellow, but still spectroscopically
pure) liquid in 60-75% yield after purification by fractional
distillation (bp ) 88-90 °C/(0.32 Torr)). It is quite thermally
robust (no decomposition was observed upon heating to 250
°
C), soluble in aliphatic and aromatic hydrocarbons, ethers,
dichloromethane, and acetonitrile, and stable for months in dry
air but susceptible to decomposition in the presence of water
or alcohols.
Group 6 Metal Carbonyl Complexes. The molybdenum
3
tricarbonyl complex {η -MeSi(CH2SMe)3}Mo(CO)3 was readily
prepared by allowing Mo(CO)6 to react with a slight excess of
MeSi(CH2SMe)3 in refluxing methylcyclohexane (eq 2), condi-
3
2 3 3
Figure 1. Molecular structure of {η -MeSi(CH SMe) }Cr(CO) .
methylcyclohexane
Mo(CO) + MeSi(CH SMe)
3
8
6
2
-3CO
Spectroscopic Studies. Spectroscopic data in solution are
consistent with the presence of tridentate facially coordinated
thioether ligands in the octahedral {η -MeSi(CH2SMe)3}M(CO)3
(M ) Cr, Mo, W) complexes. For example, their H NMR
spectra consist of three sharp singlet resonances in the ratio 3:2:
1, corresponding to the methylthio, methylene, and methylsilyl
protons, respectively. In their C{ H} NMR spectra (in tet-
rahydrofuran-d8 (THF-d8)), the chemical shifts for the three
equivalent CO groups in each compound (231.7, 222.8, and
215.6 ppm for M ) Cr, Mo, and W, respectively) are virtually
identical to those observed for the crown thioether compounds
(η -ttcn)M(CO)3. Likewise, the carbonyl region of their IR
spectra (KBr pellets) shows two intense absorptions, centered
near 1915 (A1 mode) and 1780 cm (E mode), as predicted
for the facial isomer of a rigorously octahedral tricarbonyl
3
{
η -MeSi(CH SMe) }Mo(CO) (2)
2
3
3
3
1
tions under which the product precipitated and was isolated by
filtration in ca. 90% yield. It is interesting to note that if aromatic
hydrocarbons (e.g., benzene, toluene) are used as solvents for
6
13
1
the above reaction, the known arene derivatives (η -ArH)Mo-
(
CO)3 form preferentially.12 The corresponding reactions of the
chromium or tungsten hexacarbonyls M(CO)6 (M ) Cr, W) with
MeSi(CH2SMe)3 only produced dark mixtures of unidentified
3
products. However, the complexes {η -MeSi(CH2SMe)3}-
3
15
M(CO)3 (M ) Cr, W) were conveniently obtained (65-75%
1
3
yield) by treating the labile nitrile derivatives Cr(CO)3(NCMe)3
14
-1
or W(CO)3(NCEt)3 with the ligand in benzene/THF, reactions
that proceeded to completion within minutes at room temper-
ature. The three new thioether complexes are yellow, diamag-
netic, moderately air-sensitive solids, only slightly soluble in
benzene or toluene but more so in THF, solvents in which their
solubilities decrease in the order Cr > Mo > W. Furthermore,
1
8
complex. However, a distortion from C3V symmetry in the
solid-state structures of {η -MeSi(CH2SMe)3}M(CO)3 (vide
infra) is manifested by the presence of a third, weaker band (at
ca. 1820 cm ), observed as a shoulder of the lower frequency
ν(CO) stretch (see Experimental Section). Albeit not common,
this feature is precedented for other complexes of the type L3M-
3
-
1
3
19
dissolution of {η -MeSi(CH2SMe)3}M(CO)3 (M ) Cr, Mo, W)
in polar coordinating solvents such as acetonitrile resulted in
2
0
the immediate generation of, inter alia, the adducts M(CO)3-
(CO)3.
1
3
(
NCMe)3 and the free thioether ligand, as determined by H
Structures of {η -MeSi(CH2SMe)3}M(CO)3. The molecular
structures of all three {η -MeSi(CH2SMe)3}M(CO)3 complexes
3
NMR spectroscopy. Interestingly, this observation is in contrast
to the syntheses of the related trithiacyclononane derivatives
(M ) Cr, Mo, W) were determined by single-crystal X-ray
diffraction. The complexes are isomorphous, with each asym-
metric unit containing two crystallographically independent but
chemically identical molecules differing only in the handedness
of the thioether ligands. Representative molecules from each
compound are depicted in Figures 1-3, with selected bond
lengths and angles shown in Table 1. It is worth noting that
while thioether complexes of Cr, Mo, and W are not rare, this
appears to be the first complete series of group 6 metal thioether
derivatives to be structurally characterized. The six-coordinate
3
15
16,17
15
(
η -ttcn)M(CO)3 (M ) Cr, Mo,
W ), which have been
prepared from M(CO)6 and the crown thioether in acetonitrile.
(
10) Similarly, using MeSiCl3 and 3 equiv of the lithiated thioanisole reagent
1
0a,b
LiCH2SPh‚TMEDA,
we have prepared the (phenylthio)methyl
derivative MeSi(CH2SPh)3, isolated as an off-white solid in 78%
1
0c
yield. (a) Corey, E. J.; Seebach, D. J. Org. Chem. 1966, 31, 4097-
099. (b) Amstutz, R.; Laube, T.; Schweizer, W. B.; Seebach, D.;
4
Dunitz, J. D. HelV. Chim. Acta 1984, 67, 224-236. (c) Bunich, D.;
Rabinovich, D. Unpublished results.
11) Peterson, D. J. J. Org. Chem. 1967, 32, 1717-1720.
12) (a) Pidcock, A.; Smith, J. D.; Taylor, B. W. J. Chem. Soc. A 1967,
(
(
8
72-876. (b) Nesmeyanov, A. N.; Krivykh, V. V.; Kaganovich, V.
(18) (a) Braterman, P. S. Struct. Bonding 1976, 26, 1-42. (b) Braterman,
P. S. Metal Carbonyl Spectra; Academic Press: New York, 1975.
(19) Solution IR spectra (in THF) exhibit only the two expected bands in
S.; Rybinskaya, M. I. J. Organomet. Chem. 1975, 102, 185-193. (c)
Strohmeier, W. Chem. Ber. 1961, 94, 3337-3341. (d) Angelici, R. J.
J. Chem. Educ. 1968, 45, 119-120.
-
1
the carbonyl region: for M ) Cr, ν(CO) ) 1924 and 1811 cm , for
-
1
(
13) Tate, D. P.; Knipple, W. R.; Augl, J. M. Inorg. Chem. 1962, 2, 433-
M ) Mo, ν(CO) ) 1931 and 1819 cm , and for M ) W, ν(CO) )
-1
434.
1923 and 1811 cm .
(
(
14) Kubas, G. J.; Van der Sluys, L. S. Inorg. Synth. 1990, 28, 29-33.
15) Kim, H.-J.; Do, Y.; Lee, H. W.; Jeong, J. H.; Sohn, Y. S. Bull. Korean
Chem. Soc. 1991, 12, 257-259.
(20) (a) Cotton, F. A.; Zingales, F. Inorg. Chem. 1962, 1, 145-147. (b)
Werner, H.; Deckelmann, K.; Sch o¨ nenberger, U. HelV. Chim. Acta
1970, 53, 2002-2009. (c) Armanasco, N. L.; Baker, M. V.; North,
M. R.; Skelton, B. W.; White, A. H. J. Chem. Soc., Dalton Trans.
1998, 1145-1149. (d) Haselhorst, G.; Stoetzel, S.; Strassburger, A.;
Walz, W.; Wieghardt, K.; Nuber, B. J. Chem. Soc., Dalton Trans.
1993, 83-90. (e) Siclovan, O. P.; Angelici, R. J. Inorg. Chem. 1998,
37, 432-444.
(
16) Ashby, M. T.; Lichtenberger, D. L. Inorg. Chem. 1985, 24, 636-
638.
(
17) (a) Sellmann, D.; Zapf, L. Angew. Chem., Int. Ed. Engl. 1984, 23,
8
07-808. (b) Sellmann, D.; Zapf, L. J. Organomet. Chem. 1985, 289,
57-69.

Tris[(alkylthio)methyl]silanes
Inorganic Chemistry, Vol. 38, No. 9, 1999 2213
3
Table 1. Selected Bond Lengths (Å) and Angles (deg) for {η -MeSi(CH
M ) Cr
2
SMe)
3
}M(CO)
3
Complexes
M ) Mo
M ) W
molecule A
molecule B
molecule A
molecule B
molecule A
molecule B
M-S(11)
M-S(21)
M-S(31)
M-C(1)
M-C(2)
M-C(3)
2.456(1)
2.438(1)
2.463(1)
1.833(5)
1.830(4)
1.822(5)
2.459(1)
2.464(1)
2.469(1)
1.834(5)
1.834(5)
1.836(5)
2.620(1)
2.623(1)
2.625(1)
1.974(2)
1.978(2)
1.977(2)
2.625(1)
2.615(1)
2.600(1)
1.978(2)
1.971(2)
1.966(2)
2.563(2)
2.569(2)
2.568(2)
1.942(8)
1.935(8)
1.935(7)
2.568(2)
2.559(2)
2.544(2)
1.949(7)
1.948(8)
1.948(7)
S(11)-M-S(21)
S(11)-M-S(31)
S(21)-M-S(31)
C(1)-M-C(2)
C(1)-M-C(3)
C(2)-M-C(3)
S(11)-M-C(1)
S(11)-M-C(2)
S(11)-M-C(3)
S(21)-M-C(1)
S(21)-M-C(2)
S(21)-M-C(3)
S(31)-M-C(1)
S(31)-M-C(2)
S(31)-M-C(3)
92.3(1)
86.2(1)
86.6(1)
86.6(2)
87.9(2)
88.0(2)
88.8(2)
93.0(2)
176.5(2)
95.3(1)
174.5(2)
86.9(1)
174.7(2)
91.9(2)
97.1(2)
88.4(1)
89.8(1)
86.3(1)
88.6(2)
85.5(2)
86.3(2)
93.6(1)
93.0(2)
178.9(2)
94.7(1)
176.3(2)
92.4(2)
176.5(2)
90.3(2)
91.1(2)
88.2(1)
86.8(1)
84.6(1)
88.1(1)
86.6(1)
86.1(1)
93.2(1)
94.8(1)
179.1(1)
91.5(1)
176.9(1)
90.9(1)
176.1(1)
95.8(1)
93.4(1)
84.1(1)
85.3(1)
90.9(1)
88.0 (1)
87.0(1)
87.5(1)
93.2(1)
98.1(1)
174.3(1)
92.7(1)
177.7(1)
90.3(1)
176.0(1)
88.6(1)
94.9(1)
88.0(1)
86.8(1)
84.5(1)
88.8(3)
86.5(3)
87.0(3)
92.8(2)
94.4(2)
178.4(2)
91.4(2)
177.5(2)
90.6(2)
175.9(2)
95.3(2)
93.7(2)
83.9(1)
85.3(1)
90.8(1)
88.7(3)
88.1(3)
87.8(3)
92.5(2)
98.2(2)
173.9(2)
92.1(2)
177.6(2)
90.0(2)
176.1(2)
88.5(2)
94.5(2)
the structures resemble those of the trithiacyclononane deriva-
3
16
15
tives {η -ttcn}M(CO)3 (M ) Mo, W ) as well as several other
known tricarbonyl complexes of general formula L3M(CO)3.
Furthermore, the thioether arms of each ligand display a
propeller-like arrangement about the metal, being canted relative
to the C3 axis containing the metal and the Si-C(4) group in
each complex. Although the observed C-S-C angles (average
9
9.9°) suggest little distortion of the thioether groups upon
2
1
coordination, the flexibility of the ligands is indicated by the
considerable range of M-S-C angles (between 99 and 115°).
3
The average Cr-S and Mo-S bond distances in {η -
MeSi(CH2SMe)3}M(CO)3, 2.458 and 2.618 Å, respectively, are
among the longest observed for thioether complexes of zero
2
2
23
valent chromium and molybdenum. While this observation
(
21) For comparison, a C-S-C angle of 99.1° was found by electron
diffraction for gaseous dimethyl sulfide: Iijima, T.; Tsuchiya, S.;
Kimura, M. Bull. Chem. Soc. Jpn. 1977, 50, 2564-2567.
3
Figure 2. Molecular structure of {η -MeSi(CH
2
SMe)
3
}Mo(CO)
3
.
(
22) Cr(0)-S(thioether) bond distances have been observed in the ap-
proximate range 2.34-2.46 Å: (a) Baker, E. N.; Larsen, N. G. J.
Chem. Soc., Dalton Trans. 1976, 1769-1773. (b) Lappert, M. F.;
Shaw, D. B.; McLaughlin, G. M. J. Chem. Soc., Dalton Trans. 1979,
4
27-433. (c) Lotz, S.; Schindehutte, M.; van Dyk, M. M.; Dillen, J.
L. M.; van Rooyen, P. H. J. Organomet. Chem. 1985, 295, 51-61.
d) Raubenheimer, H. G.; Kruger, G. J.; Viljoen, H. W. J. Organomet.
(
Chem. 1987, 319, 361-377. (e) van Rooyen, P. H.; Dillen, J. L. M.;
Lotz, S.; Schindehutte, M. J. Organomet. Chem. 1984, 273, 61-68.
(
f) Raubenheimer, H. G.; Boeyens, J. C. A.; Lotz, S. J. Organomet.
Chem. 1976, 112, 145-153. (g) Abel, E. W.; Cooley, N. A.; Kite,
K.; Orrell, K. G.; Sik, V.; Hursthouse, M. B.; Dawes, H. M.
Polyhedron 1989, 8, 887-891. (h) Liu, S.-T.; Tsao, C.-L.; Cheng,
M.-C.; Peng, S.-M. Polyhedron 1990, 9, 2579-2584. (i) Peach, M.
E.; Burschka, C. Can. J. Chem. 1982, 60, 2029-2037. (j) Jogun, K.
H.; Stezowski, J. J. Acta Crystallogr. 1979, B35, 2310-2313. (k)
Reisner, G. M.; Bernal, I.; Dobson, G. R. Inorg. Chim. Acta 1981,
50, 227-233. (l) Fischer, H.; Gerbing, U.; Treier, K.; Hofmann, J.
Chem. Ber. 1990, 123, 725-732. (m) Fischer, H.; Treier, K.; Gerbing,
U.; Hofmann, J. J. Chem. Soc., Chem. Commun. 1989, 667-668. (n)
Raubenheimer, H. G.; Viljoen, J. C.; Lotz, S.; Lombard, A. J. Chem.
Soc., Chem. Commun. 1981, 749-750. (o) Weber, L.; Boese, R. Chem.
Ber. 1983, 116, 514-521. (p) Kruger, G. J.; Gafner, G.; de Villiers,
J. P. R.; Raubenheimer, H. G.; Swanepoel, H. J. Organomet. Chem.
1980, 187, 333-340. (q) Kruger, G. J.; Coetzer, J.; Raubenheimer,
H. G.; Lotz, S. J. Organomet. Chem. 1977, 142, 249-263. (r) Aumann,
R.; Schr o¨ der, J.; Kr u¨ ger, C.; Goddard, R. J. Organomet. Chem. 1989,
3
Figure 3. Molecular structure of {η -MeSi(CH
2
SMe)
3
}W(CO)
3
.
complexes present distorted octahedral geometries in the solid
state, with tridentate face-capping thioether ligands. The three
M-CO groups are roughly opposite to the three M-S bonds,
with the S-M-COtrans angles being ca. 177°. In this regard,
3
78, 185-197. (s) D o¨ tz, K. H.; Erben, H.-G.; Staudacher, W.; Harms,
K.; M u¨ ller, G.; Riede, J. J. Organomet. Chem. 1988, 355, 177-191.
t) Halverson, D. E.; Reisner, G. M.; Dobson, G. R.; Bernal, I.;
Mulcahy, T. L. Inorg. Chem. 1982, 21, 4285-4290.
(

2214 Inorganic Chemistry, Vol. 38, No. 9, 1999
Yim et al.
does not imply the absence of metal-thioether π bonding
Mo-C distances (mean ) 1.974 Å). All the other interatomic
bond lengths (i.e., C-O, Si-C, and S-C) also seem to be
interactions, it is consistent with the presence of weakly bound,
3
27
labile thioether ligands in {η -MeSi(CH2SMe)3}M(CO)3. We
normal.
24a
also note that, assuming a covalent radius of 1.04 Å for sulfur
Conclusions
and using the values proposed by Cotton for the radii of
octahedral Cr(0) and Mo(0),24b the estimated lengths for Cr-S
and Mo-S single bonds are 2.52 and 2.66 Å, respectively. In
the case of the tungsten compound, the W-S bond lengths
In summary, the new tripodal thioether ligand MeSi(CH2-
SMe)3 was synthesized, and its first transition metal derivatives,
3
the group 6 metal carbonyl complexes {η -MeSi(CH2SMe)3}-
(
average 2.562 Å) are within the range of reported W(0)-SR2
M(CO)3 (M ) Cr, Mo, W), were prepared and structurally
characterized. Spectroscopic studies indicate that, electronically,
MeSi(CH2SMe)3 is fairly similar to tridentate crown thioethers
such as 1,4,7-trithiacyclononane. However, the new silane ligand
has several practical advantages over the latter, including its
ease of preparation, lower cost, and, more importantly, the
potential to accommodate different coordination environments
by modifying its steric requirements.
2
5
distances (2.51-2.59 Å). Furthermore, the observed W-S
bond lengths are also slightly shorter than the corresponding
values found in the Mo analogue, a phenomenom that is not
uncommon and is considered to be an effect of the lanthanide
contraction. With regard to the metal-CO fragments, we
observe fairly typical W-C bond lengths (mean ) 1.943 Å),
values which are also marginally shorter than the corresponding
2
6
(
23) Mo(0)-S(thioether) bond lengths have been observed in the range
2
.41-2.59 Å. See refs 4a, 8a, 16, and the following: (a) Adams, R.
Experimental Section
D.; Shiralian, M. Organometallics 1982, 1, 883-884. (b) Adams, R.
D.; Blankenship, C.; Segm u¨ ller, B. E.; Shiralian, M. J. Am. Chem.
Soc. 1983, 105, 4319-4326. (c) Morris, R. H.; Ressner, J. M.; Sawyer,
J. F.; Shiralian, M. J. Am. Chem. Soc. 1984, 106, 3683-3684. (d)
Balbach, B. K.; Koray, A. R.; Okur, A.; W u¨ lknitz, P.; Ziegler, M. L.
J. Organomet. Chem. 1981, 212, 77-94. (e) Yoshida, T.; Adachi, T.;
Ueda, T.; Watanabe, M.; Kaminaka, M.; Higuchi, T. Angew. Chem.,
Int. Ed. Engl. 1987, 26, 1171-1172. (f) Yoshida, T.; Adachi, T.;
Kaminaka, M.; Ueda, T.; Higuchi, T. J. Am. Chem. Soc. 1988, 110,
General Considerations. All reactions were performed under dry
oxygen-free nitrogen in an Innovative Technology System One-M-DC
glovebox or under argon using a combination of high-vacuum and
28
Schlenk techniques. Solvents were purified and degassed by standard
procedures, and all commercially available reagents were used as
13
14
received. Whereas Cr(CO)
3
(NCMe)
3
and W(CO)
3
(NCEt)
3
were
prepared as reported, LiCH
2
SMe was synthesized by a modified
literature procedure,11 as described below. H and C NMR spectra
were obtained on General Electric QE 300 or Varian Gemini (300 MHz)
FT spectrometers. Chemical shifts are reported in parts per million
1
13
4872-4873. (g) Adachi, T.; Sasaki, N.; Ueda, T.; Kaminaka, M.;
Yoshida, T. J. Chem. Soc., Chem. Commun. 1989, 1320-1322. (h)
Yoshida, T.; Adachi, T.; Kawazu, K.; Yamamoto, A.; Sasaki, N.
Angew. Chem., Int. Ed. Engl. 1991, 30, 982-984. (i) Gelling, A.;
Jeffery, J. C.; Povey, D. C.; Went, M. J. J. Chem. Soc., Chem.
Commun. 1991, 349-351. (j) Gelling, A.; Went, M. J.; Povey, D. C.
J. Organomet. Chem. 1993, 455, 203-210. (k) Blower, P. J.; Jeffery,
J. C.; Miller, J. R.; Salek, S. N.; Schmaljohann, D.; Smith, R. J.; Went,
M. J. Inorg. Chem. 1997, 36, 1578-1582. (l) Jacobi, A.; Huttner, G.;
Winterhalter, U. Chem. Ber./Recueil 1997, 130, 1279-1294. (m)
Grant, G. J.; Carpenter, J. P.; Setzer, W. N.; VanDerveer, D. G. Inorg.
Chem. 1989, 28, 4128-4131. (n) de Groot, B.; Loeb, S. J. Inorg.
Chem. 1990, 29, 4084-4090. (o) Hoffmann, P.; Steinhoff, A.; Mattes,
R. Z. Naturforsch. 1987, 42B, 867-873. (p) S u¨ nkel, K.; Blum, A.;
Polborn, K.; Lippmann, E. Chem. Ber. 1990, 123, 1227-1231. (q)
Yoshida, T.; Adachi, T.; Sato, K.; Baba, K.; Kanokogi, Y. J. Chem.
Soc., Chem. Commun. 1993, 1511-1513. (r) Alvarez, M.; Lugan, N.;
Mathieu, R. Inorg. Chem. 1993, 32, 5652-5657. (s) Sellmann, D.;
Binker, G.; Schwartz, J.; Knoch, F.; B o¨ se, R.; Huttner, G.; Zsolnai,
L. J. Organomet. Chem. 1987, 323, 323-338. (t) Soltek, R.; Huttner,
G.; Zsolnai, L.; Driess, A. Inorg. Chim. Acta 1998, 269, 143-156.
24) (a) Pauling, L. The Nature of the Chemical Bond, 3rd ed.; Cornell
University Press: Ithaca, NY, 1960; p 224. (b) Cotton, F. A.;
Richardson, D. C. Inorg. Chem. 1966, 5, 1851-1854.
relative to SiMe (δ ) 0 ppm) and were referenced internally with
4
respect to the residual protio solvent resonances; coupling constants
are given in hertz. IR spectra for solid and liquid samples were recorded
as KBr pellets or neat in a cell with NaCl windows, respectively, on a
-1
Midac Collegian FT spectrophotometer and are reported in cm
;
relative intensities of the absorptions are indicated in parentheses (vs
very strong, s ) strong, m ) medium, w ) weak, sh ) shoulder).
)
Elemental analyses were determined by Atlantic Microlab, Inc. (Nor-
cross, GA).
Synthesis of MeSi(CH
under a constant flow of argon, a solution of LiBu in hexanes (2.5 M,
00 mL, 250 mmol) was added using a syringe to a cold (0 °C) stirred
solution of Me S (28 mL, 381 mmol) and TMEDA (40 mL, 265 mmol)
2 3
SMe) . In a 1000 mL round-bottomed flask,
n
1
2
in pentane (60 mL), resulting in the formation of a yellow, slightly
cloudy solution. The solution was allowed to warm to room temperature
and refluxed for 2 h to complete the deprotonation reaction, producing
(
(
2 3
a suspension of the LiCH SMe reagent. A solution of MeSiCl (9.7
mL, 82.6 mmol) in pentane (80 mL) was then added in small portions
via cannula over a 30 min period to the above reaction mixture cooled
to -60 °C, resulting in the gradual formation of a white precipitate
25) See refs 15, 22h, and 23d,p, and the following: (a) Fischer, H.; Kalbas,
C.; Stumpf, R. Chem. Ber. 1996, 129, 1169-1175. (b) Abel, E. W.;
King, G. D.; Orrell, K. G.; Pring, G. M.; Sik, V.; Cameron, T. S.
Polyhedron 1983, 2, 1117-1124. (c) Wu, H.; Lucas, C. R. Inorg.
Chem. 1992, 31, 2354-2358. (d) Adams, R. D.; Falloon, S. B.; Perrin,
J. L.; Queisser, J. A.; Yamamoto, J. H. Chem. Ber. 1996, 129, 313-
(LiCl) and a yellow solution. The suspension was allowed to warm to
room temperature and refluxed for 18 h. After cooling to room
318. (e) Reisner, G. M.; Bernal, I.; Dobson, G. R. J. Organomet. Chem.
1
978, 157, 23-39. (f) Cannas, M.; Carta, G.; De Filippo, D.; Marongiu,
(26) It is interesting to note that while the magnitude of the change in atomic
radii for the elements La through Lu has historically been overrated,
leading to deserving criticism,2 its relevance to the size of the
elements following the lanthanides in the periodic table cannot be
exaggerated. At least qualitatively, the fact that the metals in the third
transition series are often smaller than their group congeners of the
second transition series is more meaningful than the lanthanide
contraction per se. In addition, a more modern view of the size
variations among and between the 5d and f-block elements invokes
the significant contribution of relativistic effects.2 (a) Lloyd, D. R.
J. Chem. Educ. 1986, 63, 502-503. (b) Pyykk o¨ , P. Chem. ReV. 1988,
88, 563-594.
(27) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A.
G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1-S19.
(28) (a) Errington, R. J. AdVanced Practical Inorganic and Metalorganic
Chemistry; Blackie Academic & Professional: London, 1997. (b)
Experimental Organometallic Chemistry; Wayda, A. L., Darensbourg,
M. Y., Eds.; American Chemical Society: Washington, D.C., 1987.
(c) Shriver, D. F.; Drezdzon, M. A. The Manipulation of Air-SensitiVe
Compounds, 2nd ed.; Wiley-Interscience: New York, 1986.
G.; Trogu, E. F. Inorg. Chim. Acta 1974, 10, 145-149. (g) Rauben-
heimer, H. G.; Kruger, G. J.; Marais, C. F.; Otte, R.; Scott, F. South
Afr. J. Chem. 1987, 40, 207-208. (h) Abel, E. W.; Orrell, K. G.;
Rahoo, H.; Sik, V.; Mazid, M. A.; Hursthouse, M. B. J. Organomet.
Chem. 1992, 437, 191-199. (i) Faller, J. W.; Zhang, N.; Chase, K.
J.; Musker, W. K.; Amaro, A. R.; Semko, C. M. J. Organomet. Chem.
6a
1994, 468, 175-182. (j) Pickering, R. A.; Jacobson, R. A.; Angelici,
R. J. J. Am. Chem. Soc. 1981, 103, 817-821. (k) Abel, E. W.; Long,
N. J.; Orrell, K. G.; Osborne, A. G.; Sik, V.; Bates, P. A.; Hursthouse,
M. B. J. Organomet. Chem. 1990, 394, 455-468. (l) Wang, H.-E.;
Cheng, M.-C.; Peng, S.-M.; Liu, S.-T. Acta Crystallogr. 1995, C51,
6b
1
98-200. (m) Long, N. J.; Martin, J.; White, A. J. P.; Williams, D.
J. J. Chem. Soc., Dalton Trans. 1997, 3083-3085. (n) Adams, R. D.;
Yamamoto, J. H.; Holmes, A.; Baker, B. J. Organometallics 1997,
1
6, 1430-1439. (o) Al-Dulaymmi, M. F. M.; Hitchcock, P. B.;
Richards, R. L. Polyhedron 1991, 10, 1549-1557. (p) Glavee, G. N.;
Daniels, L. M.; Angelici, R. J. Inorg. Chem. 1989, 28, 1751-1754.
(
4
q) Ros, R.; Vidali, M.; Graziani, R. Gazz. Chim. Ital. 1970, 100, 407-
13.

Tris[(alkylthio)methyl]silanes
Inorganic Chemistry, Vol. 38, No. 9, 1999 2215
3
temperature, the yellow supernatant solution was separated by filtration
and the white residue extracted into pentane (50 mL). The volatile
components from the combined filtrate and extract were removed under
reduced pressure to give a viscous orange liquid. Fractional vacuum
distillation of the oil yielded the desired product as a pale yellow,
Table 2. Crystallographic Data for {η -MeSi(CH
2
SMe)
3
}M(CO)
3
Complexes
M ) Cr
M ) Mo
M ) W
formula
C
10
H18CrO
3
-
C
10
H18MoO
3
-
C
10
18 3
H O -
S
3
Si
362.51
monoclinic
P2
3
S Si
3
S SiW
spectroscopically pure liquid with bp 88-90 °C at 0.32 Torr (13.5 g,
1
fw
406.45
monoclinic
/c (No. 14) P2 /c (No. 14) P2 /c (No. 14)
1 1
494.36
monoclinic
7
2%). H NMR data (in C
6
D
6
3
): δ 0.31 (s, 3 H, CH Si), 1.85 (s, 6 H,
cryst syst
space group
T, K
1
CH
120, 1 C, CH
38, 3 C, SCH
435 (s), 1423 (s), 1386 (s), 1314 (s), 1252 (s), 1136 (m), 1075 (m),
60 (s), 816 (vs), 714 (w). Anal. Calcd for C Si: C, 37.1; H, 8.0;
2
), 1.86 (s, 9 H, SCH
3
). 13C NMR data (in C
6 6
D ): δ -5.2 (q, JC-H
1
1
1
)
3
Si), 18.0 (t, JC-H ) 131, 3 C, CH
2
), 20.0 (q, JC-H
)
173(2)
198(2)
198(2)
1
1
9
3
). IR data: 2966 (s), 2911 (vs), 2879 (s), 2829 (m),
a, Å
b, Å
c, Å
8.1658(2)
15.0563(2)
26.5791(3)
90.3653(6)
3267.74(8)
8
1.474
11.53
yellow block
8.34630(6)
15.2747(2)
27.1865(4)
90.8987(9)
3465.44(10)
8
1.558
11.84
orange rod
8.1582(2)
14.9903(2)
26.7268(4)
90.6568(8)
3268.30(9)
8
2.009
75.22
yellow plate
7
18 3
H S
S, 42.5. Found: C, 37.9; H, 8.4; S, 42.1.
â, deg
3
V, Å3
Synthesis of {η -MeSi(CH
2
SMe)
3
}Cr(CO)
3
. In a 250 mL Schlenk
(NCMe)
1.40 g, 5.40 mmol) in benzene (50 mL) was treated with MeSi(CH
flask under argon, a dark brown stirred suspension of Cr(CO)
3
3
Z
D
, g cm-
3
(
2
-
c
-
1
µ(Mo KR), cm
color, habit
3
SMe) (1.20 mL, 6.04 mmol), added dropwise using a syringe. The
resulting yellow-brown solution was stirred for 15 min at room
temperature and filtered. Concentration of the filtrate to ca. 5 mL under
reduced pressure and addition of diethyl ether (30 mL) led to the
separation of a yellow microcrystalline solid, which was isolated by
R
R
1
/Rw2 [I > 2σ(I)]a 0.0474/0.1503 0.0260/0.0603 0.0404/0.0762
/Rw2 (all data)a
0.0654/0.1702 0.0338/0.0634 0.0756/0.0902
1
a
R ) ∑(|F | - |F |)/∑|F |; R ) {∑[w(Fo2 - F ) ]/∑[w(F ) }1/2.
2
2
2 2
1
o
c
o
w2
c
o
1
w- ) σ (F
2
2
2
2
filtration, washed with diethyl ether (20 mL), and dried in vacuo for 1
o
) + (aP) + bP; P ) [2F
c
o
+ max(F ,0)]/3.
1
h (1.45 g, 74%). H NMR data (in C
6
D
6
1
): δ -0.52 (s, 3 H, CH
3
Si),
). C{ H} NMR data (in THF-
), 28.7 (s, 3 C, SCH ),
31.7 (s, 3 C, CO). IR data: 2916 (m), 1913 (vs), 1818 (sh), 1778
(s, 1 C, CH
3
Si), 18.7 (s, 3 C, CH
2
), 31.1 (s, 3 C, SCH
CO). IR data: 2918 (w), 1910 (vs), 1816 (sh), 1770 (vs), 1415 (m),
374 (m), 1304 (w), 1250 (w), 1139 (m), 1084 (w), 978 (m), 964 (s),
26 (vs), 773 (s), 732 (w), 625 (w), 614 (w). Anal. Calcd for
SiW: C, 24.3; H, 3.7. Found: C, 24.6; H, 3.6.
X-ray Structure Determinations. Crystallographic data for the
2 3 3
complexes {η -MeSi(CH SMe) }M(CO) (M ) Cr, Mo, W) are
collected in Table 2. Data were collected on a Siemens P4/CCD system
3
), 215.6 (s, 3 C,
3
1
1
d
2
.08 (s, 6 H, CH
8
2
), 2.28 (s, 9 H, SCH
): δ -3.1 (s, 1 C, CH
3
3
Si), 16.3 (s, 3 C, CH
2
3
1
8
(vs), 1417 (s), 1395 (m), 1371 (m), 1318 (w), 1308 (w), 1251 (m),
C
10
H
18
O
3
S
3
1
6
135 (s), 1081 (m), 974 (m), 963 (vs), 824 (vs), 772 (vs), 732 (m),
93 (s), 641 (vs), 616 (w), 540 (s). Anal. Calcd for C10 Si:
H
18CrO
S
3 3
3
C, 33.1; H, 5.0. Found: C, 33.4; H, 5.0.
3
Synthesis of {η -MeSi(CH
2
SMe)
3
}Mo(CO)
3
. A stirred suspension
(2.50 mL, 12.58
using Mo KR radiation (λ ) 0.710 73 Å). Systematic absences in the
diffraction data determined that the space group was P2 /c (No. 14).
1
of Mo(CO) (3.00 g, 11.36 mmol) and MeSi(CH
6
2
SMe)
3
mmol) in methycyclohexane (60 mL) was heated gently under argon,
resulting in the formation, within 30 min, of a bright yellow solution.
The solution was then heated to reflux, and a pale yellow solid started
to precipitate after about 1 h. Heating was continued for an additional
The three structures are isomorphous. The asymmetric unit contains
two crystallographically independent but chemically identical molecules
differing only in the handedness of the tripodal ligands. The Mo
structure was solved by direct methods, completed from difference
Fourier maps, and refined with anisotropic thermal parameters for all
non-hydrogen atoms. The Cr and W structures were solved by
isomorphic replacement of the metal atom and similarly refined.
Empirical corrections for absorption were applied to the data. Hydrogen
atoms were treated as idealized contributions. All computations used
SHELXTL NT 5.10 and SADABS sotware (G. Sheldrick, Bruker AXS,
Madison, WI).
4
h, after which the solution was allowed to cool to room temperature.
The pale yellow microcrystalline product was isolated by filtration,
washed with pentane (20 mL), and dried in vacuo for 1 h (4.09 g,
1
8
9%). H NMR data: (in C
6
D
6
3
): δ -0.56 (s, 3 H, CH
3
Si), 1.16 (s, 6
). C{ H} NMR data (in THF-d ): δ -2.4
Si), 18.7 (s, 3 C, CH ), 29.4 (s, 3 C, SCH ), 222.8 (s, 3 C,
CO). IR data: 2924 (w), 1918 (vs), 1823 (sh), 1785 (vs), 1420 (m),
417 (m), 1380 (m), 1318 (w), 1251 (w), 1140 (m), 1085 (w), 976
w), 964 (m), 825 (s), 774 (s), 732 (w), 643 (m), 619 (m), 511 (m).
Anal. Calcd for C10 Si: C, 29.6; H, 4.5. Found: C, 29.6; H,
.4.
Synthesis of {η -MeSi(CH
flask under argon, a dark brown stirred suspension of W(CO)
1.00 g, 2.31 mmol) in a mixture of benzene (20 mL) and THF (100
mL) was treated with MeSi(CH SMe) (0.50 mL, 2.52 mmol), added
1
1
H, CH
(
2
), 2.21 (s, 9 H, SCH
3
8
s, 1 C, CH
3
2
3
1
(
Acknowledgment. We thank the Camille and Henry Dreyfus
Foundation Faculty Start-Up Grant Program for Undergraduate
Institutions, Research Corporation for a Cottrell College Science
Award, the donors of the Petroleum Research Fund, adminis-
tered by the American Chemical Society, and The University
of North Carolina at Charlotte for support of this research. We
also thank Professor Ged Parkin (Columbia University) for
helpful discussions.
3 3
H18MoO S
4
3
2
SMe)
3
}W(CO)
3
. In a 250 mL Schlenk
(NCEt)
3
3
(
2
3
dropwise using a syringe. The resulting yellow-brown solution was
stirred for 1 h at room temperature and filtered. Concentration of the
filtrate to ca. 5 mL under reduced pressure and addition of diethyl ether
Supporting Information Available: An X-ray crystallographic file,
(30 mL) led to the separation of a pale yellow microcrystalline solid,
3
in CIF format, for the structures of {η -MeSi(CH
2
SMe)
3
}M(CO)
3
(M
which was isolated by filtration, washed with diethyl ether (20 mL)
)
Cr, Mo, W) is available free of charge via the Internet at
and then with pentane (20 mL), and dried in vacuo for 30 min (0.49 g,
http://pubs.acs.org.
1
6
8%). H NMR data: (in C
6
D
6
3
): δ -0.60 (s, 3 H, CH
3
Si), 1.21 (s, 6
1
1
H, CH
2
), 2.35 (s, 9 H, SCH
3
). C{ H} NMR data (in THF-d ): δ -2.5
8
IC981001J