Synthesis and reactions of triphenylsilanethiolato complexes of manganese(II), iron(II), cobalt(II), and nickel(II)

Article abstract of DOI:10.1021/ic025715c

Reactions of Fe[N(SiMe₃)₂]₂ with 1 and 2 equiv of Ph₃SiSH in hexane afforded dinuclear silanethiolato complexes, [Fe{N(SiMe₃)₂}(μ-SSiPh₃)]₂ (1) and [Fe(SSiPh₃

Full text of DOI:10.1021/ic025715c

Inorg. Chem. 2002, 41, 5083−5090
Synthesis and Reactions of Triphenylsilanethiolato Complexes of
Manganese(II), Iron(II), Cobalt(II), and Nickel(II)
,†
Takashi Komuro,† Hiroyuki Kawaguchi,‡ and Kazuyuki Tatsumi*
Research Center for Materials Science and Department of Chemistry, Graduate School of Science,
Nagoya UniVersity, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan, and Coordination Chemistry
Laboratories, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
Received May 14, 2002
Reactions of Fe[N(SiMe3)2]2 with 1 and 2 equiv of Ph3SiSH in hexane afforded dinuclear silanethiolato complexes,
[Fe{N(SiMe3)2}(µ-SSiPh3)]2 (1) and [Fe(SSiPh3)(µ-SSiPh3)]2 (2), respectively. Various Lewis bases were readily
t
added to 2, generating mononuclear adducts, Fe(SSiPh3)2(L)2 [L ) CH CN (3a), 4-BuC H N (3b), PEt3 (3c), (LL)
3
5 4
) tmeda (3d)]. From the analogous reactions of M[N(SiMe3)2]2 (M ) Mn, Co) and [Ni(NPh2)2]2 with Ph3SiSH in the
presence of TMEDA, the corresponding silanethiolato complexes, M(SSiPh3)2(tmeda) [M ) Mn (4), Co (5), Ni (6)],
were isolated. Treatment of 3a with (PPh4)2[MoS ] or (NEt4)2[FeCl4] resulted in formation of a linear trinuclear
4
Fe−Mo−Fe cluster (PPh4)2[MoS {Fe(SSiPh3)2}2] (7) or a dinuclear complex (NEt4)2[Fe2(SSiPh3)2Cl4] (8). On the
4
other hand, the reaction of 3a with [Cu(CH CN)4](PF ) gave a cyclic tetranuclear copper cluster Cu4(SSiPh3)4 (9),
3
6
where silanethiolato ligands were transferred from iron to copper. Silicon−sulfur bond cleavage was found to occur
when the cobalt complex 5 was treated with (NBu4)F in THF, and a cobalt−sulfido cluster Co6(µ3-S)8(PPh3)6 (10)
was isolated upon addition of PPh to the reaction system. The silanethiolato complexes reported here are expected
3
to serve as convenient precursors for sulfido cluster synthesis.
Introduction
complexes containing alkyl(aryl) thiolate ligands, the coor-
dination chemistry of silanethiolates has yet to be explored.4-8
However, the use of silanethiolates has the following two
advantages in developing rational synthetic routes to transi-
tion metal-sulfido clusters. First, silicon-sulfur bonds are
expected to be more labile and more readily cleaved under
mild conditions than carbon-sulfur bonds. Second, the
Transition metal-sulfur clusters have attracted attention
in light of their relevance to various active sites of metal-
loproteins, desulfurization catalysis, and inorganic functional
materials.1 An important and challenging subject in this
chemistry is to develop rational methods to synthesize
desirable sulfur cluster complexes of high nuclearity, by
assembling suitable metal-sulfur fragments.2 For this pur-
pose, we have developed cluster-forming reactions of
preformed mononuclear thiolato complexes via carbon-
sulfur bond cleavage.3 For instance, (η5-C5Me5)Mo(StBu)3
was found to react with FeCl3, resulting in isolation of the
cubane-type cluster (η5-C5Me5)2Mo2Fe2S4Cl2.3b
(2) (a) Coucouvanis, D. Acc. Chem. Res. 1991, 24, 1-8. (b) Hidai, M.;
Kuwata, S.; Mizobe, Y. Acc. Chem. Res. 2000, 33, 46-52. (c) Li, P.;
Curtis, D. Inorg. Chem. 1990, 29, 1242-1248. (d) Adams, H.; Bailey,
N. A.; Gay, S. R.; Gill, L. J.; Hamilton, T.; Morris, M. J. J. Chem.
Soc., Dalton Trans. 1996, 2403-2407. (e) Osterloh, F.; Segal, B. M.;
Achim, C.; Holm, R. H. Inorg. Chem. 2000, 39, 980-989. (f)
Coucouvanis, D.; Hadjikyriacou, A.; Lester, R.; Kanatzidis, M. G.
Inorg. Chem. 1994, 33, 3645-3655. (g) Beauvais, L. G.; Shores, M.
P.; Long, J. R. J. Am. Chem. Soc. 2000, 122, 2763-2772. (h) Trikalitis,
P. N.; Bakas, T.; Papaefthymiou, V.; Kanatzidis, M. G. Angew. Chem.,
Int. Ed. 2000, 39, 4558-4561.
(3) (a) Arikawa, Y.; Kawaguchi, H.; Kashiwabara K.; Tatsumi, K. Inorg.
Chem. 1999, 38, 4549-4553. (b) Kawaguchi, H.; Yamada, K.;
Ohnishi, S.; Tatsumi, K. J. Am. Chem. Soc. 1997, 119, 10871-10872.
(c) Kawaguchi, H.; Tatsumi, K. Organometallics 1997, 16, 307-309.
(d) Cramer, R. E.; Yamada, K.; Kawaguchi, H.; Tatsumi, K. Inorg.
Chem. 1996, 35, 1743-1746. (e) Sunada, Y.; Hayashi, Y.; Kawaguchi,
H.; Tatsumi, K. Inorg. Chem. 2001, 40, 7072-7078. (f) Nagasawa,
T.; Kawaguchi, H.; Tatsumi, K. J. Organomet. Chem. 1999, 592, 46-
51.
As an extension of our study on thiolato/sulfido complexes
of transition metals, we have investigated the synthesis and
reactions of silanethiolato complexes.4 Compared with
* Author to whom correspondence should be addressed. E-mail: i45100a@
nucc.cc.nagoya-u.ac.jp. Fax: +81 52 789 2943.
† Nagoya University.
‡ Institute for Molecular Science.
(1) (a) Stiefel, E. I.; Matsumoto, K. Transition Metal Sulfur Chemistry,
Biological and Industrial Significance; American Chemical Society;
Washington, DC, 1996. (b) Riaz, U.; Curnow, O.; Curtis, M. D. J.
Am. Chem. Soc. 1991, 113, 1416-1417. (c) Draganjac, M. R.;
Rauchfuss, T. B. Angew. Chem., Int. Ed. Engl. 1985, 24, 742-757.
(4) Komuro, T.; Matsuo, T.; Kawaguchi, H.; Tatsumi, K. Chem. Commun.
2002, 988-989.
10.1021/ic025715c CCC: $22.00 © 2002 American Chemical Society
Published on Web 08/24/2002
Inorganic Chemistry, Vol. 41, No. 20, 2002 5083

Komuro et al.
Preparation of Fe(SSiPh3)2(CH3CN)2 (3a). A solution of
triphenylsilanethiol (1.70 g, 5.81 mmol) in hexane (85 mL) was
added to a solution of Fe[N(SiMe3)2]2 (1.11 g, 2.94 mmol) in hexane
(10 mL). The complex [Fe(SSiPh3)(µ-SSiPh3)]2 (2) immediately
precipitated as a yellow powder. After the mixture was stirred at
room temperature for 5 min, the precipitate was isolated by
decantation and dried in vacuo. The resulting solid was suspended
in 60 mL of CH3CN, giving colorless microcrystals of 3a (1.63 g,
78%). Anal. Calcd for C40H36FeN2S2Si2: C, 66.65; H, 5.03; N, 3.89;
reactivity of silanethiolato ligands can be controlled by the
steric and electronic properties of the substituents in the silyl
group. The most intriguing example of such a study is the
copper silanethiolato complex Cu(SSiMe3)(PPrn ) prepared
3 3
by Corrigan and co-workers, treatment of which with Hg-
(OAc)2(PPrn ) gave rise to the gigantic Hg/Cu/S cluster,
3 2
Hg15Cu20S25(PPrn ) .6b We herein describe the synthesis and
3 18
structures of a series of triphenylsilanethiolato complexes
of Mn(II), Fe(II), Co(II), and Ni(II). Also reported are our
preliminary findings of the stability/reactivity of these
triphenylsilanethiolato complexes.
1
S, 8.90. Found: C, 66.41; H, 4.96; N, 3.95; S, 8.76. H NMR
(CD3CN): δ 10.38 (∆ν1/2 ) 190 Hz, br, Ph), 8.31 (∆ν1/2 ) 29 Hz,
br, Ph), 6.34 (∆ν1/2 ) 22 Hz, br, Ph), 1.98 (s, CH3CN). IR
(Nujol): 2304 (m, νNC), 2276 (m, νNC) cm-1. UV-visible (λmax
nm (ꢀ, M-1 cm-1), CH3CN): 322 (4500), 264 sh.
,
Experimental Section
General. All manipulations of air- and/or moisture-sensitive
compounds were carried out under an atmosphere of dinitrogen or
argon with standard Schlenk-line techniques. Solvents were dried
and distilled over an appropriate drying agent under an atmosphere
of dinitrogen. All commercially available reagents were used as
received. The compounds M[N(SiMe3)2]2 (M ) Mn, Fe, Co)9 and
Compound 3a (0.43 g, 0.60 mmol) was dissolved in THF (30
mL) and stirred at room temperature. The solution gradually
darkened and a black powder precipitated, resulting in a colorless
solution. After the solution was stirred overnight, THF (30 mL)
was added, and the mixture was stirred for 3 more days. The
solution was reduced to half volume, and centrifuged to separate a
black solid and a colorless solution. The black solid was washed
with THF (20 mL) and dried, affording black powder (0.09 g).
Data for black powder: Anal. Found: C, 18.33; H, 2.40; S, 25.54.
Fluorescent X-ray spectrum: Fe:S:Si ) 1:1.1:0.1.
10
[Ni(NPh2)2]2 were prepared according to published methods.
1H NMR spectra were recorded on a JEOL Lambda-500
spectrometer and referenced internally to residual proton-solvent.
Chemical shifts are reported in ppm. Infrared spectra were recorded
on Nujol mulls between KBr plates on a JASCO FT/IR-410
spectrometer. For UV-visible spectra, a JASCO V-560 spectrom-
eter was used. Elemental analyses were measured with LECO-
CHNS and Yanaco MT-6 and MSU-32 microanalyzers.
Fe(SSiPh3)2(4-tBuC5H4N)2 (3b). A solution of triphenylsilane-
thiol (0.72 g, 2.5 mmol) in Et2O (50 mL) was added to a mixture
of Fe[N(SiMe3)2]2 (0.46 g, 1.22 mmol) and 4-tert-butylpyridine
(0.73 mL, 5.0 mmol) in Et2O (10 mL). The solution was stirred
for 10 min, during which yellow microcrystals of 3b precipitated.
The product was isolated by decantation (0.88 g, 80% yield). Anal.
Calcd for C54H56FeN2S2Si2: C, 71.34; H, 6.21; N, 3.08; S, 7.05.
Preparation of [Fe{N(SiMe3)2}(µ-SSiPh3)]2 (1). To a solution
of Fe[N(SiMe3)2]2 (0.36 g, 0.95 mmol) in hexane (5 mL) was added
slowly a solution of HSSiPh3 (0.27 g, 0.92 mmol) in hexane (25
mL) at 0 °C. The color of the solution changed from pale green to
brown, during which time a lemon-yellow solid precipitated. After
several minutes of stirring at 0 °C, the solution was removed by
decantation. Compound 1 was obtained as an air-sensitive lemon-
yellow crystalline powder (0.35 g, 74%). IR (Nujol): 3067 (m),
3049 (m), 1588 (w), 1429 (s), 1258 (m), 1246 (s), 1185 (w), 1110
(s), 1029 (w), 998 (w), 954 (s), 865 (s), 832 (s), 800 (m), 755 (w),
738 (m), 709 (s), 697 (s), 680 (m), 619 (w), 517 (s), 496 (s), 433
1
Found: C, 71.41; H, 6.26; N, 3.12; S, 6.87. H NMR (C6D6): δ
13.63 (∆ν1/2 ) 140 Hz, br), 7.82 (∆ν1/2 ) 25 Hz, br), 5.94 (∆ν1/2
) 21 Hz, br), 1.38 (∆ν1/2 ) 26 Hz, br). IR (Nujol): 3062 (m),
3047 (m), 1615 (s), 1544 (w), 1499 (m), 1427 (s), 1274 (w), 1261
(w), 1228 (w), 1184 (w), 1104 (s), 1068 (m), 1022 (m), 998 (w),
842 (w), 831 (s), 746 (s), 738 (m), 705 (s), 683 (s), 622 (w), 560
(s), 508 (s), 502 (s), 494 (s), 467 (w), 438 (m), 428 (w), 418 (m)
cm-1. UV-visible (λmax, nm (ꢀ, M-1 cm-1), CH2Cl2): 394 (1500),
306 (4700), 254 sh.
(m) cm-1
.
Fe(SSiPh3)2(PEt3)2 (3c). Reaction of Fe[N(SiMe3)2]2 (0.29 g,
0.76 mmol) and triphenylsilanethiol (0.43 g, 1.5 mmol) in the
presence of PEt3 (1.5 mL, 2.2 mmol, 20% toluene solution) in
hexane (50 mL) yielded 0.58 g of 3c as colorless crystals in 87%.
Anal. Calcd for C48H60FeP2S2Si2: C, 65.88; H, 6.91; S, 7.33.
Found: C, 65.90; H, 6.99; S, 7.10. 1H NMR (C6D6): δ 11.89 (∆ν1/2
) 380 Hz, br), 10.15 (∆ν1/2 ) 56 Hz, br), 6.66 (∆ν1/2 ) 29 Hz,
br), 4.08 (∆ν1/2 ) 370 Hz, br). IR (Nujol): 3065 (m), 3044 (m),
1585 (w), 1566 (w), 1427 (s), 1306 (w), 1259 (w), 1186 (w), 1106
(s), 1065 (w), 1038 (w), 1029 (w), 997 (w), 848 (w), 768 (w), 745
(m), 739 (m), 734 (m), 703 (s), 682 (s), 620 (w), 562 (s), 550 (s),
503 (s), 491 (s), 436 (w), 419 (w) cm-1. UV-visible (λmax, nm (ꢀ,
M-1 cm-1), ether): 372 sh (1700), 305 sh (3100), 259 sh.
Fe(SSiPh3)2(tmeda) (3d). A mixture of Fe[N(SiMe3)2]2 (1.01
g, 2.67 mmol) and TMEDA (0.80 mL 5.3 mmol) in Et2O (10 mL)
was treated as described for 3b with triphenylsilanethiol (1.56 g,
5.3 mmol) in Et2O (50 mL). Compound 3d was isolated as colorless
crystals (1.71 g, 85%). Anal. Calcd for C42H46FeN2S2Si2: C, 66.82;
H, 6.14; N, 3.71; S, 8.49. Found: C, 66.74; H, 6.03; N, 3.58; S,
8.22. 1H NMR (CDCl3): δ 20.53 (∆ν1/2 ) 180 Hz, br,tmeda), 7.73
(∆ν1/2 ) 23 Hz, br, Ph), 5.82 (∆ν1/2 ) 16 Hz, br, Ph). IR (Nujol):
1426 (s), 1106 (s), 702 (s), 567 (s), 558 (s), 500 (s) cm-1. UV-
visible (λmax, nm (ꢀ, M-1 cm-1), CH2Cl2): 305 (5800), 260 sh.
(5) (a) Kova´cs, I.; Lebuis, A.-M.; Shaver, A. Organometallics 2001, 20,
35-41. (b) Gioland, D. M.; Rauchfuss, T. B.; Clark, G. M. Inorg.
Chem. 1987, 26, 3080-3082. (c) Chojnacki, J.; Becker, B.; Konitz,
A.; Potrzebowski, M. J.; Wojnowski, W. J. Chem. Soc., Dalton Trans.
1999, 3063-3068. (d) Beker, B.; Radacki, K.; Wojnowski, W. J.
Organomet. Chem. 1996, 521, 39-49. (e) Beker, B.; Wojnowski, W.;
Peters, K.; Peters, E.-M.; von Schnering, H. G. Polyhedron 1990, 9,
1659-1666. (f) Bauer, A.; Schneider, W.; Angermaier, K.; Schier,
A.; Schmidbauer, H. Inorg. Chim. Acta 1996, 251, 249-253. (g) Cai,
L.; Holm, R. H. J. Am. Chem. Soc. 1994, 116, 7177-7188.
(6) (a) Tran, D. T. T.; Corrigan, J. F. Organometallics 2000, 19, 5202-
5208. (b) Tran, D. T. T.; Taylor, N. J.; Corrigan, J. F. Angew. Chem.,
Int. Ed. 2000, 39, 935-937.
(7) (a) Liang, H.-C.; Shapley, P. A. Organometallics 1996, 15, 1331-
1333. (b) Shapley, P. A.; Liang, H.-C.; Dopke, N. C. Organometallics
2001, 20, 4700-4704.
(8) Silaneselenolato and -tellurolato complexes were reported. (a) Timber-
lake, J. M.; Green, J.; Christou, V.; Arnold, J. J. Chem. Soc., Dalton
Trans. 1998, 4029-4033. (b) Gerlach, C. P.; Arnold, J. Inorg. Chem.,
1996, 35, 5770-5780. (c) Gindelbergerde, D. E.; Arnold, J. Orga-
nometallics 1996, 13, 4462-4468. (d) Cary, D. R.; Arnold, J. Inorg.
Chem. 1994, 33, 1791-1796. (e) Bonasia, P. J.; Gindelbergerde, D.
E.; Dabbousi, B. O.; Arnold, J. J. Am. Chem. Soc. 1992, 114, 5209-
5214. (f) Bonasia, P. J.; Arnold, J. Inorg. Chem. 1992, 31, 2508-
2514. (g) Arnold, J. Prog. Inorg. Chem. 1995, 34, 353-417.
(9) Andersen, R. A.; Faegri, K., Jr.; Green, J. C.; Haaland, A.; Lappert,
M. F.; Leung, W.-P.; Rypdal, K. Inorg. Chem. 1988, 27, 1782-1786.
(10) Hope, H.; Olmstead, M. M.; Murray, B. D.; Power, P. P. J. Am. Chem.
Soc. 1985, 107, 712-713.
5084 Inorganic Chemistry, Vol. 41, No. 20, 2002

Silanethiolato Complexes
Mn(SSiPh3)2(tmeda) (4). The same procedure as used for 3d
was followed. Reaction of Mn[N(SiMe3)2]2 (0.29 g, 0.77 mmol)
and triphenylsilanethiol (0.43 g, 1.5 mmol) in the presence of
TMEDA (0.22 mL, 1.5 mmol) in Et2O (25 mL) yielded 0.42 g of
4 as colorless crystals in 72%. Anal. Calcd for C42H46MnN2S2Si2:
C, 66.90; H, 6.15; N, 3.71; S, 8.50. Found: C, 66.84; H, 6.15; N,
[FeCl4] (0.24 g, 0.52 mmol) in CH3CN (25 mL). The resulting
homogeneous solution was stirred for 20 min at room temperature.
The resulting brown solution was concentrated in vacuo, and then
addition of Et2O (30 mL) to the solution caused the separation of
a colorless powder. This material was isolated by decantation and
dried in vacuo to give 8 in 91% yield (0.51 g). Anal. Calcd for
C52H70Cl4Fe2N2S2Si2: C, 56.94; H, 6.43; N, 2.55; S, 5.85. Found:
1
3.73; S, 8.33. H NMR (CDCl3): δ 7.6 (∆ν1/2 ) 240 Hz, br). IR
1
(Nujol): 3065 (m), 3048 (m), 1584 (w), 1567 (w), 1429 (s), 1355
(w), 1287 (m), 1262 (w), 1193 (w), 1185 (w), 1167 (w), 1156 (w),
1125 (w), 1105 (s), 1063 (w), 1024 (m), 1007 (w), 997 (w), 950
(m), 793 (m), 743 (s), 736 (m), 702 (s), 683 (s), 622 (w), 565 (s),
C, 56.76; H, 6.35; N, 2.72; S, 5.77. H NMR (CD3CN): δ 8.27
(∆ν1/2 ) 24 Hz, br), 6.69 (∆ν1/2 ) 31 Hz, br), 6.54 (∆ν1/2 ) 220
Hz, br), 2.97 (∆ν1/2 ) 25 Hz, br, CH3CH2N), 1.20 (∆ν1/2 ) 20 Hz,
br, CH3CH2N). IR (Nujol): 1579 (m), 1435 (s), 1306 (w), 1265
(w), 1099 (s), 1031 (w), 998 (w), 875 (w), 844 (w), 821 (w), 743
(m), 733 (s), 705 (s), 690 (s), 611 (m), 534 (s), 521 (m), 481 (m)
cm-1. UV-visible (λmax, nm (ꢀ, M-1 cm-1), CH3CN): 294 sh
(5400), 250 sh.
503 (s), 489 (s), 436 (m), 428 (w) cm-1
.
Co(SSiPh3)2(tmeda) (5). Addition of a Et2O (20 mL) solution
of triphenylsilanethiol (0.43 g, 1.5 mmol) into a mixture of Co-
[N(SiMe3)2]2 (0.28 g, 0.74 mmol) and TMEDA (0.22 mL, 1.5
mmol) in Et2O (10 mL) followed by workup similar to 3d afforded
0.39 g of 5 as blue crystals (70%). Anal. Calcd for C42H46CoN2S2-
Si2: C, 66.54; H, 6.12; N, 3.70; S, 8.46. Found: C, 66.25; H, 6.05;
[Ph3SiSLi(thf)]4. A solution of Ph3SiCl (10.0 g, 33.9 mmol) in
THF (80 mL) was added to an excess of Li (2.30 g, 0.33 mol) in
THF (40 mL) at -78 °C. The reaction mixture was allowed to
warm slowly to room temperature and was stirred for 12 h. The
mixture was added to a suspension of sulfur (1.08 g, 33.7 mmol)
in THF (20 mL) at -78 °C. The reaction mixture was stirred at
room temperature for an additional 12 h. The yellow solution was
evaporated to dryness. The residue was extracted with toluene (120
mL) and centrifuged to remove LiCl. The supernatant was
concentrated under vacuum to afford yellow crystals of [Ph3SiSLi-
(thf)]4 (8.21 g, 65%). According to the X-ray study, the lithium
salt has a cubane geometry, where vertexes are occupied by sulfur
atoms and lithium atoms in an alternative manner. Crystal data:
tetragonal, space group P421c (No. 144), a ) b ) 15.665(8) Å, c
) 17.182(9) Å, V ) 4216(3) Å3, Z ) 8, Dc ) 0.990 Mg/m-3, Mo
KR, µ ) 2.07 cm-1, R(Rw) ) 0.085(0.087), GOF ) 1.17. Anal.
Calcd for C88H92O4Li4Si4S4: C, 71.32; H, 6.26; S, 8.65. Found:
1
N, 3.62; S, 8.05. H NMR (CDCl3): δ 7.25 (∆ν1/2 ) 20 Hz, br),
5.38 (∆ν1/2 ) 85 Hz, br), 5.22 (∆ν1/2 ) 16 Hz, br). IR (Nujol):
3062 (m), 1585 (w), 1566 (w), 1428 (s), 1305 (w), 1286 (m), 1262
(w), 1187 (w), 1102 (s), 1043 (w), 1025 (m), 998 (w), 950 (m),
798 (m), 747 (m), 739 (m), 699 (s), 684 (m), 622 (w), 563 (s), 507
(s), 495 (s), 467 (w), 431 (m), 418 (m) cm-1. UV-visible (λmax
,
nm (ꢀ, M-1 cm-1), CH2Cl2): 684 (750), 572 (180), 362 (3300),
312 (4700), 260 sh.
Ni(SSiPh3)2(tmeda) (6). To a suspension of [Ni(NPh2)]2 (0.39
g, 0.49 mmol) in toluene (15 mL) containing TMEDA (0.30 mL,
2.0 mmol) was added triphenylsilanethiol (0.59 g, 2.0 mmol) in
toluene (15 mL). The mixture immediately became a dark yellow
homogeneous solution that was stirred for 10 min at room
temperature. After the solution was centrifuged to remove a small
amount of an insoluble solid, the supernatant was evaporated to
dryness. The resulting residue was washed with Et2O/hexane (1:1)
to give 0.31 g of 6 as a yellow powder in 41% yield. Anal. Calcd
for C42H46N2NiS2Si2: C, 66.57; H, 6.12; N, 3.70; S, 8.46. Found:
1
C, 70.91; H, 6.45; S, 9.07. H NMR (C6D6): δ 8.1 (m, 36H, Ph),
7.2 (m, 24H, Ph), 1.86 (br, 16H, thf), 3.75 (br, 16H, thf). IR
(Nujol): 3063 (m), 3045 (m), 1427 (s), 1260 (w), 1183 (w), 1104
(s), 1045 (m), 896 (w), 743 (m), 701 (s), 686 (m), 622 (w), 575
(s), 499 (s), 431 (w) cm-1
.
1
C, 65.92; H, 5.91; N, 3.69; S, 8.38. H NMR (CDCl3): δ 10.35
(∆ν1/2 ) 98 Hz, br), 8.74 (∆ν1/2 ) 20 Hz, br), 7.16 (∆ν1/2 ) 16
Hz, br). IR (Nujol): 3064 (m), 1428 (s), 1106 (s), 1018 (w), 951
(w), 802 (w), 743 (m), 704 (s), 683 (m), 621 (w), 569 (s), 560 (s),
502 (s), 490 (s), 436 (w) cm-1. UV-visible (λmax, nm (ꢀ, M-1
cm-1), CH2Cl2): 543 (200), 433 (4900), 402 sh (2900), 378 sh
(2100), 345 sh (1200), 264 sh.
Cu4(SSiPh3)4 (9). Method 1. A solution of [Cu(CH3CN)4](PF6)
(0.27 g, 0.72 mmol) in CH3CN (15 mL) was added to a slurry of
3a (0.26 g, 0.36 mmol) in CH3CN (10 mL). The solution was stirred
at room temperature for 15 min, during which time a colorless
crystalline solid precipitated. The resulting solid was isolated by
decantation. Recrystallization from toluene yielded 9 as colorless
crystals (0.21 g, 81%).
(PPh4)2[MoS4{Fe(SSiPh3)2}2] (7). Addition of (PPh4)2[MoS4]
(0.28 g, 0.31 mmol) in CH3CN (25 mL) to a slurry of 3a (0.45 g,
0.62 mmol) in CH3CN (10 mL) immediately gave a homogeneous
dark red solution. The mixture was stirred for 20 h at room
temperature and evaporated to dryness. The residue was washed
with Et2O (15 mL) and then dissolved in CH2Cl2 (15 mL). The
solution was centrifuged to remove an insoluble material. The
supernatant was concentrated, and Et2O was added. Cooling the
solution to -25 °C gave black microcrystals of 7‚CH2Cl2 (0.50 g,
71%). Anal. Calcd for C121H102Cl2Fe2MoP2S8Si4: C, 64.15; H, 4.54;
S, 11.32. Found: C, 64.48; H, 4.70; S, 10.91. 1H NMR (CD3CN):
δ 11.44 (∆ν1/2 ) 370 Hz, br), 8.94 (∆ν1/2 ) 71 Hz, br), 7.86 (∆ν1/2
) 23 Hz, br), 7.65 (∆ν1/2 ) 53 Hz, br), 6.68 (∆ν1/2 ) 38 Hz, br),
5.45 (s, CH2Cl2). IR (Nujol): 1584 (w), 1426 (s), 1183 (w), 1105
(s), 1027 (w), 996 (w), 741 (m), 723 (s), 699 (s), 689 (s), 681 (s),
621 (w), 553 (s), 526 (s), 501 (s), 468 (w), 459 (w), 423 (w), 413
(w, Mo-S) cm-1. UV-visible (λmax, nm (ꢀ, M-1 cm-1), CH2Cl2):
611 sh (1300), 499 (12000), 387 sh (13000), 349 sh (16000), 319
(19000), 262 sh.
Method 2. Addition of a CH3CN (25 mL) solution of [Cu(CH3-
CN)4](PF6) (1.18 g, 3.17 mmol) into [Ph3SiSLi(thf)]4 (1.19 g, 0.80
mmol) in toluene (25 mL) followed by a workup analogous to
method 1 produced 0.83 g of 9 in 73% yield. Anal. Calcd for
C72H60Cu4S4Si4: C, 60.90; H, 4.26; S, 9.03. Found: C, 60.82; H,
4.21; S, 8.76. 1H NMR (500 MHz, CDCl3): δ 7.44 (m, 24H, Ph),
7.36 (m, 11H, Ph), 7.21 (m, 19H, Ph). IR (Nujol): 1586 (w), 1426
(s), 1302 (w), 1260 (w), 1186 (w), 1109 (s), 1029 (w), 997 (w),
850 (w), 738 (m), 708 (s), 696 (s), 681 (m), 620 (w), 542 (s), 533
(s), 501 (s), 490 (s), 429 (m) cm-1. UV-visible (λmax, nm (ꢀ, M-1
cm-1), CH2Cl2): 284 sh (19000), 270 sh (21000).
Reaction of Co(SSiPh3)2(tmeda) with (NBu4)F. To a mixture
of 5 (0.29 g, 0.38 mmol) in THF (20 mL) and PPh3 (0.20 g, 0.76
mmol) in THF (10 mL) was added slowly (NBu4)F (0.75 mL, 1.0
M THF solution). The deep blue solution immediately turned black.
After being stirred for 2 h, the solution was evaporated to dryness.
The remaining oil was extracted with CH3CN and the solvent was
removed. To the residue was added toluene and the mixture was
centrifuged to remove insoluble materials. After evaporation, the
resulting solid was extracted with CH2Cl2 (7 mL) and Et2O was
(NEt4)2[Fe2(SSiPh3)2Cl4] (8). To a suspension of 3a (0.37 g,
0.51 mmol) in CH3CN (10 mL) was added a solution of (NEt4)2-
Inorganic Chemistry, Vol. 41, No. 20, 2002 5085

Komuro et al.
Table 1. Crystallographic Data for Compounds 1, 3a-d, 4-6, 8, and 9
1
3a
3b
3c
3d‚CH2Cl2
empirical formula
fw
C48H66Fe2N2S2Si6
1015.39
C40H36FeN2S2Si2
720.88
C54H56FeN2S2Si2
909.19
C48H64FeP2S2Si2
879.12
C43H48Cl2FeN2S2Si2
839.91
cryst syst
space group
a/Å
b/Å
monoclinic
P21/n (No. 14)
12.1281(7)
16.2285(3)
15.2438(5)
monoclinic
Cc (No. 9)
8.875(2)
22.64(1)
18.723(4)
triclinic
P1h (No. 2)
12.713(1)
18.553(5)
10.814(2)
92.85(2)
98.68(1)
103.67(1)
2440.3(9)
2
triclinic
P1h (No. 2)
13.732(3)
13.906(5)
13.303(4)
103.39(2)
103.57(2)
88.09(2)
2401.7(1)
2
triclinic
P1h (No. 2)
14.243(9)
16.064(9)
10.451(4)
92.06(4)
100.20(3)
66.42(5)
2155.2(2)
2
c/Å
R/deg
â/deg
114.055(2)
91.12(2)
γ/deg
V/Å3
2739.7(2)
2
7.68
6518
3591
0.051
0.075
3761.1(2)
4
6.05
3325
3142
0.072
0.093
Z
µ(Mo KR)/cm-1
4.81
7650
6363
0.061
5.48
7157
5021
0.052
6.58
7090
6158
0.071
total data collected
reflns with [I > 3σ(I)]
R
Rw
0.084
0.077
0.120
4‚CH2Cl2
5‚2CH2Cl2
6‚2CH2Cl2
8
9
empirical formula
fw
cryst syst
space group
a/Å
b/Å
c/Å
C43H48Cl2MnN2S2Si2
839.00
C44H50Cl4N2CoS2Si2
927.93
monoclinic
C2/c (No. 15)
35.8012(10)
11.0545(6)
C44H50Cl4N2NiS2Si2
927.70
monoclinic
C2/c (No. 15)
35.806(6)
C52H70Cl4Fe2N2S2Si2
1096.94
triclinic
P1h (No. 2)
10.855(2)
13.914(5)
9.983(3)
94.42(4)
102.93(2)
108.65(2)
1374.4(8)
1
C72H60Cu4S4Si4
1420.09
triclinic
12.308(5)
12.308(5)
13.154(2)
11.090(4)
98.06(20
109.63(2)
96.91(2)
1647.2(1)
1
triclinic
P1h (No. 2)
14.359(7)
16.100(8)
10.616(5)
92.23(4)
100.07(3)
66.06(4)
2207.1(2)
2
11.0410(8)
27.789(5)
27.8316(8)
R/deg
â/deg
122.6191(8)
122.860(7)
γ/deg
V/Å3
9277.4(6)
8
7.74
43436
5052
0.056
0.079
9227.9(2)
8
8.27
4629
4604
0.061
0.093
Z
µ(Mo KR)/cm-1
6.00
5998
3709
0.097
8.76
4188
3128R
0.062
15.15
6084
3990
0.036
total data collected
reflns with [I > 3σ(I)]
R
Rw
0.160
0.084
0.052
layered. Over 10 days, black crystals and a dark-brown paste were
formed. The resulting mixture was washed with CH3CN and Et2O.
Black prisms of Co6S8(PPh3)6‚CH2Cl2 (10‚CH2Cl2, 13 mg, 9%) were
Results and Discussion
Reaction of Fe[N(SiMe3)2]2 with Ph3SiSH. Addition of
1 equiv of Ph3SiSH to a hexane solution of Fe[N(SiMe3)2]2
at room temperature caused an immediate color change from
light green to brown, and a lemon-yellow solid of [Fe{N-
(SiMe3)2}(µ-SSiPh3)]2 (1) precipitated. The amide-thiolato
complex was isolated in 74% yield as an extremely air-
sensitive lemon-yellow crystalline powder, which was in-
soluble in aliphatic hydrocarbon solvents. The IR spectrum
of 1 exhibited characteristic bands arising from bis(trimeth-
ylsilyl)amide and triphenylsilanethiolato ligands, and its
dimeric structure was revealed by X-ray structural analysis.
1
separated manually. H NMR (500 MHz, CDCl3): δ 7.2-6.8 (m,
90H, Ph), 5.29 (s, 1H, CH2Cl2). IR (Nujol): 3052 (m), 1585 (w),
1569 (w), 1479 (m), 1432 (s), 1186 (w), 1090 (m), 1071 (w), 1028
(w), 998 (w), 741 (m), 691 (s), 618 (w), 524 (s), 508 (m), 496 (w),
435 (w) cm-1. UV-visible (lmax, nm, CH2Cl2): 492 sh, 432, 345,
266 sh.
X-ray Crystal Structure Determination. Crystallographic data
are summarized in Table 1. Diffraction data were collected on
Rigaku AFC7-MSC/ADSC Quantum1 CCD (for 1 at 193 K),
R-AXIS-4 (for 3a-d, 4, and 6 at 173 K), Mercury CCD (for 5 at
193 K), and AFC5S (for 9 at room temperature) diffractometers,
using monochromated Mo K radiation. Crystals of 1, 3a-d, 4, 5,
and 6 were coated in oil and cooled under a cold nitrogen stream,
while those of 9 were mounted in glass capillaries and sealed under
argon.
The structures were solved with use of direct methods and
standard difference map techniques, and were refined by full-matrix
least-squares procedures on F by using the CrystalStructure package.
Anisotropic refinement was applied to all non-hydrogen atoms,
and all the hydrogen atoms were put at calculated positions. For 8,
the methylene carbons of the NEt4+ countercations are disordered
with the occupancy factors of 50:50. In the case of 3d, 4, 5, and 6,
atoms of the crystal solvents (CH2Cl2) were disordered and iso-
tropically refined, and no hydrogen atoms of CH2Cl2 were included.
Additional crystallographic data are given in the Supporting
Information.
The X-ray derived molecular structure of 1 is illustrated
in Figure 1, and selected bond distances and angles are given
in Table 2. The two Fe(II) centers are bridged by two
silanethiolato ligands, and a crystallographic inversion center
resides in the center of the molecule. Being bound to one
terminal amide ligand, each Fe atom assumes a trigonal
planar geometry, where the sum of the angles at the Fe atom
is 360.0°. The average Fe-S bond distance of 2.343 Å and
5086 Inorganic Chemistry, Vol. 41, No. 20, 2002

Silanethiolato Complexes
Figure 1. Structure of [Fe{N(SiMe3)2}(µ-SSiPh3)]2 (1) showing 50%
probability ellipsoids.
Figure 2. Structures of Fe(SSiPh3)2(CH3CN)2 (3a, left) and Fe(SSiPh3)2-
(tmeda) (3d, right) showing 50% probability ellipsoids.
Table 2. Selected Bond Distances (Å) and Angles (deg) in
[Fe{N(SiMe3)2}(SSiPh3)]2 (1)
giving four-coordinate Lewis base adducts, Fe(SSiPh3)2(L)2
[L ) CH3CN (3a), 4-tBuC5H4N (3b), PEt3 (3c); (L)2 ) tmeda
(3d)]. Complexes 3b-d were also prepared by the reactions
of Fe[N(SiMe3)2]2 with triphenylsilanethiol in Et2O or hexane
containing the corresponding Lewis bases. According to the
X-ray structural analysis, these four Lewis base adducts are
all monomeric, and their combustion analyses are consistent
with the formulation. They were isolated in 70-90% yields
as either colorless (3a, 3c, 3d) or yellow (3b) crystalline
solids. Their broad NMR signals indicate that 3a-d are
paramagnetic. The IR spectrum of 3a shows two CtN
stretching bands at 2304 and 2276 cm-1. These bands are
slightly shifted to higher frequencies relative to that of free
acetonitrile (2250 cm-1), which has been observed for η1-
coordinated acetonitrile molecules.12
Fe-Fe′
Fe-S′
S-Si1
N-Si3
2.979(1)
2.345(1)
2.160(2)
1.730(4)
Fe-S
Fe-N
N-Si2
2.340(1)
1.892(3)
1.714(4)
S-Fe-S′
Fe-S-Si
N-Fe-S
Fe-N-Si2
Si2-N-Si3
101.04(4)
107.76(6)
126.7(1)
120.5(2)
124.5(2)
Fe-S-Fe′
Fe′-S-Si
N-Fe-S′
Fe-N-Si3
78.96(4)
109.79(6)
132.24(12)
114.8(2)
the Fe-N distance of 1.892(3) Å are both comparable to
those of Fe(II) complexes with bridging thiolates, [Fe2-
(SC6H2-2,4,6-tBu3)4 (Fe-S ) 2.366 Å) and Fe3(SC6H2-2,4,6-
iPr)4[N(SiMe3)2]2 (Fe-S ) 2.343, 2.364 Å; Fe-N ) 1.882
Å)].11 The amide nitrogen is also nearly planar as is
evidenced by the sum of the angles (359.8°) at the nitrogen
atom. The planarity at the amide nitrogen may be due to the
steric bulk of the silyl substituents and/or Fe-N π bonding
interactions. Each FeNSi2 plane is twisted from the Fe2S2
plane, where the dihedral angle between the planes is 61.1°.
The triphenylsilyl substituents on the thiolate sulfur atoms
are oriented up and down from the Fe2S2 plane. The transoid
conformation of triphenylsilyl substituents and the twist of
the FeNSi2 and Fe2S2 planes are probably caused by the steric
congestion among the silyl groups of Ph3SiS and (Me3Si)2N
ligands. The Fe-Fe distance of 2.979(1) Å is significantly
shorter than those of the related Fe(II) complexes, Fe2(SC6H2-
2,4,6-tBu3)4 [3.554 Å] and Fe3(SC6H2-2,4,6-iPr3)4[N(SiMe3)2]2
[3.243(1), 3.354(1) Å],11 which suggests Fe-Fe bonding
interactions in the structure of 1. The acute Fe-S-Fe angle
of 78.96(4)° supports this argument.
When Fe[N(SiMe3)2]2 was reacted in hexane with 2 equiv
of Ph3SiSH, a large amount of a light yellow powder was
formed. The IR spectrum of the product shows only the bands
characteristic of the triphenylsilanethiolato ligand, and the
Fe:S ratio was estimated to be 1:2 by the X-ray fluorescence
microanalysis. We tentatively formulate the product as [Fe-
(SSiPh3)(µ-SSiPh3)]2 (2). Attempts to grow crystals suitable
for X-ray study have not been successful. However, complex
2 was found to react instantaneously with Lewis bases, and
The crystal structures of all the base adducts, 3a-d, were
determined by X-ray analysis. They have a common slightly
distorted tetrahedral geometry at Fe, which is coordinated
by two silanethiolate sulfur atoms and two base atoms (N
or P). Since their structures are very much alike, only those
of 3a and 3d are shown in Figure 2. Selected geometrical
parameters of 3a-d are compared in Table 3. Although there
is little difference in their Fe-S distances (2.29-2.32 Å),
which are similar to those of the related thiolato complex
Fe(S-2,6-iPr2C6H3)2(1-methylimidazole)2 (av 2.316 Å),13 the
S-Fe-S angles vary notably from 122° to 136°. The small
(11) (a) Power, P. P.; Shoner, S. C. Angew. Chem., Int. Ed. Engl. 1991,
30, 330-332. (b) MacDonnell, F. M.; Ruhlandt-Senge, K.; Ellison, J.
J.; Holm, R. H.; Power, P. P. Inorg. Chem. 1995, 34, 1815-1822.
(12) Shin, J. H.; Savage, W.; Murphy, V. J.; Bonanno, J. B.; Churchill, D.
G.; Parkin, G. J. Chem. Soc., Dalton Trans. 2001, 1723-1753.
Inorganic Chemistry, Vol. 41, No. 20, 2002 5087

Komuro et al.
Table 3. Selected Bond Distances (Å) and Angles (deg) in Fe(SSiPh3)2(L)2 [L ) CH3CN (3a), 4-tBu-C5H4N (3b), PEt3 (3c)] and M(SSiPh3)2(tmeda)
[M ) Fe (3d), Mn (4), Co (5), Ni (6)]
3a
3b
3c
3d
4
5
6
M-S1
M-S2
S1-Si1
S2-Si2
M-L
2.322(2)
2.294(2)
2.106(2)
2.109(2)
2.058(7)
2.074(7)
2.303(1)
2.304(1)
2.101(1)
2.100(1)
2.116(3)
2.115(3)
2.311(2)
2.304(2)
2.104(2)
2.110(2)
2.458(2)
2.486(2)
2.326(1)
2.321(2)
2.103(2)
2.103(2)
2.191(4)
2.218(4)
2.381(3)
2.390(3)
2.107(5)
2.095(4)
2.27(1)
2.277(2)
2.271(1)
2.102(2)
2.099(2)
2.118(4)
2.141(5)
2.271(2)
2.276(2)
2.100(2)
2.110(2)
2.085(5)
2.113(5)
2.246(9)
M-S1-Si1
M-S2-Si2
S1-M-S2
L-M-L
105.07(9)
110.73(8)
122.50(7)
102.3(3)
110.2(2)
110.6(2)
102.9(2)
106.0(2)
119.31(6)
117.42(6)
128.77(4)
91.3(1)
113.89(9)
101.62(9)
102.75(9)
112.45(9)
118.85(7)
116.95(8)
135.21(6)
108.78(6)
105.17(7)
96.58(6)
111.53(7)
109.30(7)
136.08(5)
82.9(2)
100.0(1)
109.2(1)
109.9(1)
105.7(1)
109.9(2)
110.2(2)
139.0(1)
82.4(4)
104.7(3)
108.4(3)
108.4(3)
99.4(3)
111.61(7)
113.37(8)
133.56(6)
87.0(2)
101.8(1)
111.9(1)
110.7(1)
102.3(1)
110.95(9)
109.75(7)
140.82(7)
87.7(2)
110.2(2)
98.4(2)
S-M-L
101.56(6)
107.80(7)
99.4(2)
108.3(2)
bite angle of 82.9(8)° for chelating TMEDA in 3d, relative
to the L-Fe-L angles in 3a-c, is accompanied by the large
S-Fe-S angle. It seems that steric repulsion between
silanethiolate and L (or TMEDA) determines the S-Fe-S
bond angle. In the case of 3c, the long Fe-P bonds reduce
steric congestion around Fe, thereby allowing the S-Fe-S
angle to open up. Another distortion from the ideal tetrahedral
geometry can be seen in the dihedral angle between the FeS2
plane and the plane defined by two base atoms (N or P) and
Fe, which are 88.8° for 3a, 81.9° for 3b, 85.1° for 3c, and
84.6° for 3d.
Synthesis of M(SSiPh3)2(tmeda) (M ) Mn, Co, Ni). A
series of mononuclear iron(II) silanethiolato complexes, Fe-
(SSiPh3)2(L)2, were synthesized in high yield by the reactions
of Fe[N(SiMe3)2]2 with triphenylsilanethiol in the presence
of Lewis bases. These reactions proceeded smoothly, and
the products were easily purified. On the other hand, the
reactions of FeCl2 with [Ph3SiSLi(thf)]4 and Lewis bases
were not straightforward and the yields of silanethiolato
complexes were low. Since the protonolysis of the iron bis-
amide complex with silanethiol seems to be a superior route
to the silanethiolato complexes, we applied this method to
the preparation of other transition metal complexes of the
type M(SSiPh3)2(tmeda) [M ) Mn (4), Co (5), Ni (6)]. Thus,
treatment of M[N(SiMe3)2]2 (M ) Mn, Co) in the presence
of TMEDA followed by standard workup afforded 4 and 5
as colorless and blue crystals, respectively. From the
analogous reaction of [Ni(NPh2)2]2 we isolated 6 as yellow
Figure 3. Structure of the anion part of (NEt4)2[Fe2(SSiPh3)2Cl4] (8)
showing 50% probability ellipsoids.
According to the X-ray diffraction analysis, the manganese
complex 4 was crystallized in the triclinic P1h space group,
being isomorphic to 3d, while 5 and 6 were crystallized in
the monoclinic C2/c space group. Crystals of 3d and 4
contain one CH2Cl2 molecule in per asymmetric unit, and
those of 5 and 6 contain two CH2Cl2 molecules. The
molecular structures of 4, 5, and 6, are very similar to that
of 3d shown in Figure 3, and their geometrical parameters
are added to Table 3. In a distorted tetrahedral geometry,
the dihedral angles between the MN2 and MS2 planes in 3d
(84.6°) and 4 (84.9°) are slightly larger than those of 5 (83.0°)
and 6 (82.4°). The N-M-N angles of 3d [82.9(2)°] and 4
[82.4(4)°] are smaller than those of 5 [87.0(2)°] and 6
[87.7(2)°], and the S-M-S angles are in the range between
133.56(6)° and 140.82(7)°. No obvious correlation can be
seen between these slight distortions from tetrahedral ge-
ometry and steric effects. The M-N distances decrease in
the following order, 4 (Mn, 2.26 Å av) > 3d (Fe, 2.205 Å)
> 5 (Co, 2.130 Å) > 6 (Ni, 2.099 Å), paralleling the ionic
radii of the metal atoms. Although the M-S distances in 4
(2.386 Å), 3d (2.324 Å), and 5 (2.274 Å) follow the same
trend, the average Ni-S distance in 6 is as long as the Co-S
distance of 5. The reason for the long Ni-S bond in 6 is not
clear.14
1
crystals. The H NMR spectra of 4-6 in CDCl3 showed
broad resonances, implying that these complexes are para-
magnetic at room temperature. Their IR spectra are similar
to that of 3d, and the combustion analyses were all consistent
with the common formulation M(SSiPh3)2(tmeda).
Reactions of Bis(triphenylsilanethiolato) Complexes.
The stability of the iron bis(triphenylsilanethiolato) com-
(13) Forde, C. E.; Lough, A. J.; Morris, R. H.; Ramachandran, R. Inorg.
Chem. 1996, 35, 2747-2751.
5088 Inorganic Chemistry, Vol. 41, No. 20, 2002

Silanethiolato Complexes
Table 4. Selected Bond Distances (Å) and Angles (deg) in
(NEt4)2[Fe2(SSiPh3)2Cl4] (8)
plexes Fe(SSiPh3)2(L)2 in THF solution varies depending on
the lability of the ligand L. The acetonitrile and pyridine
adducts, 3a and 3b, decompose in THF at room temperature
within several hours to form an insoluble black solid, while
degradation of the phosphine adduct 3c occurs more slowly
and its colorless THF solution turns brown overnight.
Attempts to characterize the degradation products have not
been successful. During the degradation process, the ligands
L might be replaced by THF molecules to produce an
unstable intermediate Fe(SSiPh3)2(thf)2, which then leads to
unidentified polymers/oligomers. On the other hand, the
tmeda adduct 3d did not show any sign of decomposition in
THF at room temperature for 4 days, as monitored by UV-
visible spectroscopy. The related neutral four-coordinate
Fe(II) complexes, Fe(E-2,6-iPr2C6H3)2(1-methylimidazole)2
(E ) S, Se)13 and Fe(OCPh3)2(thf)2,15 are known to be stable
in solution. Thus, the instability of 3a-c in THF may have
something to do with the reactivity of the silicon-sulfur bond
upon dissociation of L (and THF).
Fe- - -Fe′
Fe-S′
Fe-Cl2
3.589(2)
2.450(2)
2.257(2)
Fe-S
Fe-Cl1
S-Si
2.416(2)
2.259(2)
2.116(2)
S-Fe-S′
84.92(6)
116.34(8)
115.06(7)
Fe-S-Fe′
Fe′-S-Si
95.08(6)
Fe-S-Si
128.82(9)
Cl1-Fe-Cl2
atom is tetrahedrally coordinated by two triphenylsilane-
thiolato ligands and two sulfur atoms of the MoS4 unit.
Treatment of 3a with 1 equiv of (NEt4)2[FeCl4] in CH3-
CN immediately gave a brown homogeneous solution.
Considering the facile silicon-sulfur bonds in 3a, we
anticipated that this reaction might proceed via silicon-sulfur
bond cleavage to give a sulfido cluster of iron. However, a
dinuclear chlorido/triphenylsilanethiolato complex, (NEt4)2-
[Fe2(SSiPh3)2Cl4] (8), was isolated as colorless crystals in
91% yield, as a result of ligand redistribution between 3a
and (NEt4)2[FeCl4]. The IR spectrum indicated the presence
of the tetraethylammonium cation and the triphenylsilane-
thiolate group. The combustion analysis is consistent with
the formulation of 8, and the dinuclear structure was revealed
by X-ray diffraction analysis.
The facile dissociation of acetonitrile from 3a prompted
us to examine its reactions with (PPh4)2[MoS4], (NEt4)2-
[FeCl4], and [Cu(CH3CN)4](PF6). The treatment of 3a with
0.5 equiv of (PPh4)2[MoS4] in CH3CN proceeded smoothly,
and an Fe2Mo cluster, (PPh4)2[MoS4{Fe(SSiPh3)2}2] (7), was
isolated as black crystals in 71% yield after recrystallization
of the crude product from CH2Cl2/Et2O. The IR spectrum
of 7 shows a weak absorption at 413 cm-1 assignable to the
bridging Mo-S stretching vibrations, and no ModS stretch-
ing bands were observed. While the X-ray structure analysis
of 7 was carried out,16 the poor quality of the crystal prevents
us from discussing its metric parameters in detail. However,
the data clearly show a linear Fe-Mo-Fe cluster, which is
similar to the core geometry of [MoS4(FeCl2)2]2-.17 Each iron
The structure of the anion of 8 is shown in Figure 3, and
Table 4 lists selected bond distances and angles. A crystal-
lographic inversion center lies in the middle of the Fe2S2
core. The two FeII centers assume a distorted tetrahedral
coordination geometry, and are bridged by two silanethiolate
sulfurs. Two chlorides are bound to each Fe center, and the
dihedral angle between the FeS2 and FeCl2 planes is 83.2°.
The two triphenylsilyl groups are oriented trans to each other
to avoid steric repulsion. The Fe2S2 core is planar with an
Fe- - -Fe separation of 3.589(2) Å, which is longer by 0.61
Å than that of 1, and there is no Fe-Fe bonding interaction.
The large Fe-S-Fe angle of 95.08(6)° is consistent with
the absence of the Fe-Fe bonding. In the Fe2S2 core, there
are two sets of unequal Fe-S bond distances differing by
0.034 Å. The average Fe-S distance of 2.433 Å is obviously
longer than that of 1 (2.343 Å), because of the four-
coordinated nature of the Fe centers for 8.
(14) In a series of tetrahedral tetrakis-thiolato complexes, (PPh4)2[M(SPh)4],
the M-S distances decrease substantially in going from Mn (av 2.442
Å) to Fe (2.353 Å) to Co (2.328 Å) to Ni (2.288 Å). (a) Swenson,
D.; Baenzinger, N. C.; Coucouvanis, D. J. Am. Chem. Soc. 1978, 100,
1932-1934. (b) Coucouvanis, D.; Swenson, D.; Baenzinger, N. C.;
Murphy, C.; Holah, D. G.; Sfarnas, N.; Simopoulos, A.; Kostikas, A.
J. Am. Chem. Soc. 1981, 103, 3350-3362.
(15) Bartlett, R. A.; Ellison, J. J.; Power, P. P.; Shoner, S. C. Inorg. Chem.
1991, 30, 2888-2894.
(16) Crystal data for 7‚2CH2Cl2: C122H104S8Si4P2Cl4Fe2Mo, M ) 2350.38,
monoclinic, P21/n (No. 14), a ) 17.573(5) Å, b ) 26.297(3) Å, c )
27.633(9) Å, â ) 93.59(3)°, V ) 12744.3(5) Å3, Z ) 4, R ) 0.167,
Rw ) 0.204.
When 3a was treated with 2 equiv of [Cu(CH3CN)4](PF6)
in CH3CN, a ligand transfer reaction took place, and a cyclic
tetranuclear complex Cu4(SSiPh3)4 (9) was obtained as
(17) Coucouvanis, D.; Baenziger, N. C.; Simhon, E. D.; Stremple, P.;
Swenson, D.; Simopoulos, A.; Kostikas, A.; Petrouleas, V.; Papa-
efthymiou, V. J. Am. Chem. Soc. 1980, 102, 1732-1734.
Inorganic Chemistry, Vol. 41, No. 20, 2002 5089

Komuro et al.
the terminal silanethiolates (av 2.104 Å for 3a-d, 4, 5, and
6). The elongation of the Si-S bond implies that the S-Si
pπ-dπ overlap interactions are smaller for the bridging
silanethiolates, and that the Siδ+-Sδ- ionic bond character
increases.
Finally, we attempted to induce an S-Si bond cleaving
reaction of the Co complex, 5, with (NBu4)F. Thus, when 5
was treated with (NBu4)F in THF in the presence of PPh3,
the solution immediately darkened to black. Recrystallization
of the crude product from CH2Cl2 afforded the known
hexanuclear cobalt-sulfido cluster Co6(µ3-S)8(PPh3)6 (10),
albeit in low yield.19 Compound 10 was identified by X-ray
analysis, and the structure has an octahedral Co6 core, and
each Co3 face is capped by µ3-S.20 In addition, each Co atom
is further coordinated by a phosphine ligand. An obvious
driving force for the S-Si bond rupture of 5 is the formation
of a thermally stable silicon-fluorine bond. We anticipate
that the series of triphenylsilanethiolato complexes reported
in this paper will be utilized, perhaps with appropriate
desilylation reagents, as convenient precursors for the
synthesis of metal/sulfide clusters.
Figure 4. Structure of Cu4(SSiPh3)4 (9) showing 50% probability
ellipsoids.
Table 5. Selected Bond Distances (Å) and Angles (deg) in
Cu4(SSiPh3)4 (9)
Cu1-Cu2
Cu1-S1
Cu2-S2
S1-Si1
2.852(1)
2.168(1)
2.157(1)
2.153(2)
Cu1-Cu2′
Cu1-S2
Cu2-S1′
S2-Si2
3.027(1)
2.168(1)
2.160(1)
2.142(2)
Cu1-Cu2-Cu1′
S1-Cu1-S2
Cu1-S1-Cu2′
Cu1-S1-Si1
Cu1-S2-Si2
87.64(4)
174.18(4)
88.79(5)
92.56(6)
100.03(6)
Cu2-Cu1-Cu2′
S1′-Cu2-S2
Cu1-S2-Cu2
Cu2′-S1-Si1
Cu2-S2-Si2
92.36(4)
167.13(4)
82.50(5)
102.25(6)
115.10(6)
colorless crystals. The soft silanethiolato ligand appears to
prefer the softer Cu(I) center to Fe(II). The X-ray derived
structure is shown in Figure 4, and selected bond distances
and angles are listed in Table 5. The molecule consists of
an eight-membered Cu4S4 ring, and two halves of the
tetrameric structure are related by an inversion center. Thus
the Cu4 core is crystallographically planar, and the sulfur
atoms are slightly off the Cu4 plane (-0.26 Å for S1 and
+0.22 Å for S2). This planar arrangement of four copper
atoms resembles the geometry of [Cu(SR)]4 [R ) C6H3-2,6-
(SiMe3)2, Si(OtBu)3].5f,18 The two triphenylsilyl groups of
adjacent silanethiolato ligands are situated above the Cu4S4
plane, and the other two groups are below the Cu4S4 plane.
The S-Cu-S angles slightly deviate from linearity with the
average being 170.66 °, while the average Cu-S-Cu angle
is 85.64 °. The Cu4 square geometry is slightly distorted in
such a way that two Cu-Cu distances [2.852(1) Å] are
shorter than the other two [3.027(1) Å]. It is also worthy to
note that the Si-S bonds of the bridging silanethiolate
ligands (av 2.143 Å for 1, 8, and 9) are longer than those of
Acknowledgment. H.K. thanks the Tokuyama Science
Foundation for partial support of this work.
Supporting Information Available: X-ray crystallographic files
in CIF format. This material is available free of charge via the
Internet at http://pubs.acs.org.
IC025715C
(19) (a) Cecconi, F.; Ghilardi, C. A.; Midollini, S.; Orlandini, A.; Zanello,
P. Polyhedron 1986, 5, 2021-2031. (b) Fenske, D.; Ohmer, J. Angew.
Chem., Int. Ed. Engl. 1987, 26, 148-151. (c) Hong, M. C.; Huang,
Z. Y.; Lei, X. J.; Wei, G. W.; Kang, B. S.; Liu, H. Q. Polyhedron
1991, 10, 927-934.
(20) Crystal data for 10‚CH2Cl2: C109H92S8Cl2P6Co6, M ) 2268.75,
triclinic, P1h (No. 2), a ) 13.9808(8) Å, b ) 15.011(2) Å, c )
15.352(1) Å, R ) 118.138(3)°, â ) 114.736(3)°, γ ) 92.432(7)°,
V ) 2462.1(5) Å3, Z ) 1, R ) 0.049, Rw ) 0.079.
(18) Block, E.; Kang, H.; Ofori-Okai, G.; Zubieta, J. Inorg. Chim. Acta
1990, 167, 147-148.
5090 Inorganic Chemistry, Vol. 41, No. 20, 2002