Synthesis, structures, solution behavior, and reactions of thiolato-bridged diruthenium carbonyl phosphine complexes

Article abstract of DOI:10.1021/om9710024

Dinuclear thiolato-bridged complexes [Ru₂(CO)₄(μ-SR)₂(PR′₃) ₂] (R′ = Ph, Me) have been readily prepared from the reaction of [Ru₂(CO)₄(MeCN)₄(PR′₃) ₂][BF₄]₂ (R′ = Ph (1), Me (2)) with RSH (R = ^tBu, ⁱPr, Ph) and Et₃N at ambient temperature. Although only the syn form of [Ru₂(CO)₄(M-S^tBu)₂(PPh ₃)₂] (3) and only the anti form of [Ru₂(CO)₄(μ-SPh)₂(PMe₃) ₂] (6) were found, an equilibrium mixture of both the syn (isomer A) and anti (isomer B) forms was present in solution for [Ru₂(CO)₄(μ-SⁱPr)₂(PPh ₃)₂] (4) and [Ru₂(CO)₄(μ-SPh)₂(PPh₃) ₂] (5). The spectral data support that the syn form (4A) is the major isomer of 4, while the anti form (5B) is the major isomer of 5. The two thiolato bridges are located cis to the two phosphine ligands in solid-state structures 3, 4A, and 5B, but they are located cis to only one of the two ligands whereas they are trans to the other in structure 6. Iodination of 3-6 gave one identical product [Ru₂(CO)₄(μ-SR)²I²(PR′ ₃)₂] (R′ = Ph, R = ^tBu (7), ⁱPr (8), Ph (9); R′ = Me, R = Ph (10)). Both spectral and structural evidence shows that 7-10 exist in the syn form with no Ru-Ru bonding interaction. The relative orientation of the two thiolato bridges with respect to the two phosphine ligands present in 6 remains in structure 10, in spite of the change from anti to syn. The reactions of the diiodide complexes [Ru₂(CO)₄(M-SR)₂I₂(PR′ ₃)₂3] with R″S anions give either [Ru₂(CO)₄(μ-SR)₂(PR′₃) ₂] and R″SSR″ or [Ru₂-(CO)₄(μ-SR)₂(SR″) ₂(PR′₃)₂].

Full text of DOI:10.1021/om9710024

1790
Organometallics 1998, 17, 1790-1797
Syn th esis, Str u ctu r es, Solu tion Beh a vior , a n d Rea ction s
of Th iola to-Br id ged Dir u th en iu m Ca r bon yl P h osp h in e
Com p lexes
Kom-Bei Shiu*
Department of Chemistry, National Cheng Kung University, Tainan, Taiwan 701
Sue-Lein Wang and Fen-Ling Liao
Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 300
Michael Y. Chiang
Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan 804
Shie-Ming Peng and Gene-Hsiang Lee
Department of Chemistry, National Taiwan University, Taipei, Taiwan 106
J u-Chun Wang and Lin-Shu Liou
Department of Chemistry, Soochow University, Taipei, Taiwan 111
Received November 13, 1997
Dinuclear thiolato-bridged complexes [Ru2(CO)4(µ-SR)2(PR′3)2] (R′ ) Ph, Me) have been
readily prepared from the reaction of [Ru2(CO)4(MeCN)4(PR′3)2][BF4]2 (R′ ) Ph (1), Me (2))
with RSH (R ) tBu, iPr, Ph) and Et3N at ambient temperature. Although only the syn form
of [Ru2(CO)4(µ-StBu)2(PPh3)2] (3) and only the anti form of [Ru2(CO)4(µ-SPh)2(PMe3)2] (6)
were found, an equilibrium mixture of both the syn (isomer A) and anti (isomer B) forms
was present in solution for [Ru2(CO)4(µ-SiPr)2(PPh3)2] (4) and [Ru2(CO)4(µ-SPh)2(PPh3)2] (5).
The spectral data support that the syn form (4A) is the major isomer of 4, while the anti
form (5B) is the major isomer of 5. The two thiolato bridges are located cis to the two
phosphine ligands in solid-state structures 3, 4A, and 5B, but they are located cis to only
one of the two ligands whereas they are trans to the other in structure 6. Iodination of 3-6
t
i
gave one identical product [Ru2(CO)4(µ-SR)2I2(PR′3)2] (R′ ) Ph, R ) Bu (7), Pr (8), Ph (9);
R′ ) Me, R ) Ph (10)). Both spectral and structural evidence shows that 7-10 exist in the
syn form with no Ru-Ru bonding interaction. The relative orientation of the two thiolato
bridges with respect to the two phosphine ligands present in 6 remains in structure 10, in
spite of the change from anti to syn. The reactions of the diiodide complexes [Ru2(CO)4(µ-
SR)2I2(PR′3)2] with R′′S anions give either [Ru2(CO)4(µ-SR)2(PR′3)2] and R′′SSR′′ or [Ru2-
(CO)4(µ-SR)2(SR′′)2(PR′3)2].
In tr od u ction
Diiron thiolato-bridged complexes, [Fe2(CO)4(µ-SR)2L2]
(L ) CO, phosphine, phosphite, one or one-half diphos-
phine or -arsine ligand; R ) alkyl, phenyl, or aryl), have
been studied extensively in terms of synthesis, reactiv-
ity, and spectroscopic measurements.4 The existence of
two isomers, syn and anti, with a common4-6 arrange-
ment for the two axially coordinated ligands L )
phosphine, trans to the metal-metal bond (Chart 1),
Transition-metal complexes with sulfur ligands are
of significant interest not only because they often
display unusual structures and novel reactivity1 but also
because they can serve as synthetic analogues for the
active sites of metalloprotein,2 and show some relevance
to metal sulfide hydrodesulfurization and demercura-
tion catalysts.3
(2) (a) Coucouvanis, D. Adv. Inorg. Chem. 1992, 38. 1. (b) Coucou-
vanis, D. In Molybenum Enzymes, Cofactors, and Model systems;
Stiefel, E. I., Coucouvanis, D., Newton, W. E., Eds.; American Chemical
Society: Washington, DC, 1993; p 304. (c) Rees, D. C.; Chan, M. K.;
Kim, J . Adv. Inorg. Chem. 1994, 40, 89.
(3) (a) Angelici, R. J . Acc. Chem. Res. 1988, 21, 387. (b) Chen, J .;
Daniels, L. M.; Angelici, R. J . J . Am. Chem. Soc. 1990, 112, 199. (c)
Wiegand, B. C.; Friend, C. M. Chem. Rev. 1992, 92, 491. (d) Riaz, V.;
Curnow, O. J .; Curtis, M. D. J . Am. Chem. Soc. 1994, 116, 4357. (e)
Bianchini, C.; Meli, A. J . Chem. Soc., Dalton Trans. 1996, 801. (f) Hill,
A. F.; Wilton-Ely, J . D. E. T. Organometallics 1997, 16, 4517.
* To whom correspondence should be addressed. Fax: (+886) 6 274
0552. E-mail: kbshiu@mail.ncku.edu.tw.
(1) For recent reviews, see: (a) Holm, R. H.; Ciurli, S.; Weigel, J . A.
Prog. Inorg. Chem. 1990, 38, 1. (b) Krebs, B.; Henkel, G. Angew. Chem.,
Int. Ed. Engl. 1991, 30, 769. (c) Shibahara, T. Coord. Chem. Rev. 1993,
123, 73. (d) Saito, T. In Early Transition Metal Clusters with π-Donor
Ligands; Chisholm, M. H., Ed.; VCH: New York, 1995; Chapter 3. (e)
Dance, I.; Fisher, K. Prog. Inorg. Chem. 1994, 41, 637. (f) Stiefel, E. I.
Ed. Transition Metal Sulfur Chemistry; American Chemical Society:
Washington, DC, 1996.
S0276-7333(97)01002-9 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 03/31/1998

Diruthenium Thiolato-Bridged Complexes
Organometallics, Vol. 17, No. 9, 1998 1791
Ch a r t 1
Exp er im en ta l Section
All solvents were dried and purified by standard methods
(ethers, paraffins, and arenes from potassium with benzophe-
none as indicator; halocarbons and acetonitrile from CaH2 and
alcohols from the corresponding alkoxide) and were freshly
distilled under nitrogen immediately before use. All reactions
and manipulations were carried out in standard Schlenk ware,
connected to a switchable double manifold providing vacuum
and nitrogen. Reagents were used as supplied by Aldrich. 1H
and 31P NMR spectra were measured on a Brueker AMC-400
(1H, 400 MHz; 31P, 162 MHz; 13C, 100 MHz) NMR spectrom-
eter. 1H chemical shifts (δ in ppm, J in hertz) are defined as
positive downfield relative to internal MeSi4 (TMS) or the
deuterated solvent, while 31P chemical shifts are referred to
external 85% H3PO4. The IR spectra were recorded on a Bio-
Rad FTS 175 instrument. The following abbreviations were
used: s, strong (IR); m, medium; s, singlet (NMR); d, doublet;
h, heptet; m, multiplet. Microanalyses were carried out by
the staff of the Microanalytical Service of the Department of
Chemistry, National Cheng Kung University.
and equilibrated isomerization favoring one isomer or
the other were recognized for some types of compounds.
Thermal oxidative and reductive decompositions yield-
ing sulfides, disulfides, and thiols were also reported.
In contrast the chemistry of diruthenium thiolato-
bridged complexes are still relatively unexplored.5
In this paper, we present the following new informa-
tion: (1) the reactions between [Ru2(CO)4(MeCN)4-
(PR′3)2][BF4]2 (R′ ) Ph (1), Me (2)) and two thiolate
anions via RSH/Et3N can occur even at ambient tem-
perature to afford the Ru-Ru singly bonded compounds
Syn th esis of [Ru 2(CO)4(µ-SR)2(P R′3)2] (R′ ) P h , R ) tBu
i
(3), P r (4), P h (5); R′ ) Me, R ) P h (6)). To a solution of
5b
[Ru2(CO)4(MeCN)4(PR′3)2][BF4]2 (0.26 mmol) dissolved in 20
mL of MeCN were added carefully deaerated HSR (1 mL) and
Et3N (2 mL). The solution was stirred for 2 h at ambient
temperature (ca. 28 °C), forming an orange-yellow precipitate
for starting compounds with R′ ) Ph and solution for the
compounds with R′ ) Me. The solvent and volatiles were then
removed under vacuum. Recrystallization from CH2Cl2/MeOH
gave pure product.
t
i
[Ru2(CO)4(µ-SR)2(PR′3)2] (3-6) (R ) Bu, Pr, Ph; R′ )
Ph, Me); (2) the facile interconversion between syn and
anti forms of [Ru2(CO)4(µ-SiPr)2(PPh3)2] (4) and [Ru2-
(CO)4(µ-SPh)2(PPh3)2] (5) is observed at ambient tem-
perature in solution; (3) the first crystallographically
characterized syn and anti forms of the diruthenium
thiolato-bridged carbonyl phosphine complexes are pre-
sented, adopting either a common geometry in 3-5,
with the two thiolato bridges cis to the two phosphine
groups observed previously in diiron thiolato-bridged
complexes,4i or an unprecedented geometry, with the
two thiolato bridges cis to one but trans to the other
phosphine ligand in 6; (4) iodination of 3-6 affords the
single diiodide adducts (7-10) all in the syn form, where
the unique geometry observed in 6 is retained in its
diiodide adduct 10; and (5) the reactions of [Ru2(CO)4-
(µ-SR)2I2(PR′3)2] with R′′S- via R′′SH/Et3N produce
either the substituted product [Ru2(CO)4(µ-SR)2(SR′′)2-
(PR′3)2] or the reductive-deiodination products [Ru2-
(CO)4(µ-SR)2(PR′3)2] with apparently external R′′S-
being oxidized into R′′SSR′′.
3: Anal. Calcd for C48H48O4P2Ru2S2: C, 56.68; H, 4.75.
Found: C, 56.61; H, 4.75. Yield: 87%. IR (CH2Cl2): vCO, 2001
s, 1965 m, 1931 s cm-1
.
1H NMR (25 °C, acetone-d6, 400
MHz): δ 0.64 (s, 18 H), 7.53 (m, 30 H). 31P{1H} NMR (25 °C,
162 MHz): δ 27.21 (s, 2 P) in acetone-d6 and 17.78 (s, 2 P) in
CDCl3.
4: Anal. Calcd for C46H44O4P2Ru2S2: C, 55.86; H, 4.48.
Found: C, 55.68; H, 4.47. Yield: 88%. IR (CH2Cl2): vCO, 2010
s, 2001 s, 1974 m, 1964 m, 1945 s, 1935 s cm-1 1H NMR (25
.
°C, CDCl3, 400 MHz): δ 0.32 (d, 12 H, J ) 6.6), 2.54 (h, 2 H)
for 4A; and δ 0.31 (d, 6 H, J ) 6.2), 1.03 (d, 6 H, J ) 6.2), 2.39
(h, 1 H), 2.71 (h, 1 H) for 4B. 31P{1H} NMR (25 °C, CDCl3,
162 MHz): δ 19.97 (s, 2 P) for 4A, and δ 26.54 (s, 2 P) for 4B.
5: Anal. Calcd for C52H40O4P2Ru2S2: C, 59.08; H, 3.81.
Found: C, 59.15; H, 3.92. Yield: 84%. IR (CH2Cl2): vCO, 2016
s, 1979 m, 1951 s cm-1 1H NMR (25 °C, CDCl3, 400 MHz): δ
.
6.68 (m, 10 H), 7.38 (m, 30 H). 31P{1H} NMR (25 °C, CDCl3,
162 MHz): δ 21.98 (s, 2 P) for 5A, and 26.15 (s, 2 P) for 5B.
6: 89% yield. Anal. Calcd for C16H32O4P2Ru2S2: C, 31.16;
H, 5.23. Found: C, 31.07; H, 5.22. IR (CH2Cl2): vCO, 2043 s,
(4) (a) Dahl, L. F.; Wei, C.-H. Inorg. Chem. 1963, 2, 328. (b) Hieber,
W.; Kaiser, K. Chem. Ber. 1969, 102, 4043. (c) Crow, J . P.; Cullen, W.
R. Can. J . Chem. 1971, 49, 2948. (d) De Beer, J . A.; Haines, R. J . J .
Chem. Soc. A 1971, 3271. (e) Maresca, L.; Greggio, F.; Sbrignadello,
G.; Bor, G. Inorg. Chim. Acta 1971, 5, 667. (f) De Beer, J . A., Haines,
R. J . J . Organomet. Chem. 1972, 36, 297. (g) De Beer, J . A.; Haines,
R. J . J . Organomet. Chem. 1972, 37, 173. (h) Ellgen, P. C.; Gerlach, J .
N. Inorg. Chem. 1973, 12, 2526. (i) Borgne, G. L.; Grandjean, D.;
Mathieu, R.; Poilblanc, R. J . Organomet. Chem. 1977, 131, 429. (j)
Nametkin, N. S.; Tyurin, V. D.; Kukina, M. A. J . Organomet. Chem.
1978, 149, 355. (k) Shriver, D. F.; Whitmire, K. H. In Comprehensive
Organometallic Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W.,
Eds.; Pergamon: Oxford, England, 1982; Vol. 4, Chapter 31, p 280. (l)
Hawker, P. H.; Twigg, M. V. In Comprehensive Coordination Chem-
istry; Wilkinson, G. W., Gillard, R. D., Eds.; Pergamon: Oxford,
England, 1987; Vol. 4. Chapter 44.1, p 1238. (m) Whitmire, K. H, In
Comprehensive Organometallic Chemistry II; Abel, E. W., Stone, F.
G. A., Wilkinson, G., Eds.; Pergamon: Oxford, England, 1995; Vol. 7,
Chapter 1, p 65.
1983 s, 1970 sh, 1937 m cm-1
.
1H NMR (25 °C, acetone-d6,
400 MHz): δ 1.84 (d, 9 H, J ) 10.1), 1.70 (d, 9 H, J ) 10.1),
7.04 (m, 10 H). 31P{1H} NMR (298 or 220 K, acetone-d6, 162
MHz): δ 6.42 (s, 1 P), 15.17 (s, 1P).
Iod in a tion of 3-6. To a solution of [Ru2(CO)4(µ-SR)2-
(PR′3)2] (0.12 mmol) dissolved in 20 mL of CH2Cl2 was added
dropwise 4 mL (ca. 0.13 mmol) of an I2 solution prepared by
dissolving 0.129 g (0.51 mmol) of I2 in 15 mL of CH2Cl2. The
solution was stirred for 10 min at ambient temperature. The
product, 7-10, was separated as a major yellow band by thin-
layer chromatography (silica gel, CH2Cl2:hexane ) 1:1), using
TLC plates (Kieselguhr 60 F254, E. Merck), and recrystallized
from CH2Cl2/MeOH.
[Ru 2(CO)4(µ-StBu )2I2(P P h 3)2] (7): 77% yield. Anal. Calcd
for C48H48I2O4P2Ru2S2: C, 45.36; H, 3.81. Found: C, 45.21;
H, 3.83. 1H NMR (25 °C, acetone-d6, 400 MHz): δ 0.76 (s, 18
H), 7.73 (m, 30 H). 31P{1H} NMR (300 or 220 K, acetone-d6,
162 MHz): δ 44.58 (s, 2 P). IR (CH2Cl2): vCO, 2057 s, 2049 s,
(5) (a) Andreu, P. L.; Cabeza, J . A.; Riera, V.; Robert, F.; J eannin,
Y. J . Organomet. Chem. 1989, 372, C15. (b) Shiu, K.-B.; Li, C.-H.; Chan,
T.-J .; Peng, S.-M.; Cheng, M.-C.; Wang, S.-L.; Liao, F.-L. Organome-
tallics 1995, 14, 524. (c) Soler, J .; Ros, J .; Carrasco, M. R.; Ruiz, A.;
Alvarez-Larena, A.; Piniella, J . F. Inorg. Chem. 1995, 34, 6211.
(6) Andreu, P. L.; Cabeza, J . A.; Miguel, D.; Riera, V.; Villa, M. A.;
Garcia-Granda, S. J . Chem. Soc., Dalton Trans. 1991, 533.
2003 s cm-1
.

1792 Organometallics, Vol. 17, No. 9, 1998
Shiu et al.
Ta ble 1. Cr ysta l Da ta
5B
compd
formula
fw
3‚CH3OH‚2H2O
49H48O7P2Ru2S2
1077.1
4A
8
10
C
C46H44O4P2Ru2S2
988.9
C52H40O4P2Ru2S2
1057.8
C22H28O4P2Ru2S2
684.67
C22H28I2O4P2Ru2S2
988.9
color, habit
diffractometer used
space group
a, Å
b, Å
orange-yellow, chunk
Siemens SMART-CCD Siemens P4
yellow, rhombohedron orange-yellow, chunk
yellow, prism
Rigaku AFC7S
monoclinic, P21/n
11.673(3)
17.716(4)
13.496(2)
90
94.59(2)
90
2782.0(10)
4
orange-yellow, equant
Siemens SMART-CCD
Nonius
monoclinic, C2/c
48.905(2)
10.759(2)
19.528(2)
90
97.97(2)
90
10175(2)
8
1.406
orthorhombic, Cmc21
triclinic, P1h
9.8356(14)
11.168(3)
22.065(5)
82.16(3)
78.92(3)
79.640(16)
2326.8(8)
2
monoclinic, P21/c
10.769(2)
24.144(2)
13.097(2)
90
112.56(2)
90
3144.8(8)
4
1.982
24.522(4)
11.318(2)
16.037(4)
90
90
90
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
4451.1(14)
4
D
calcd, g cm-3
1.455
1.509
1.635
λ(Mo KR), Å
F(000)
0.710 73
4384
0.710 73
2208
0.7107
1063
0.710 69
1368
0.710 73
1792
unit cell detn
no. 2θ range, deg
scan type
whole data
hemisphere
4-54
25, 14-28
25, 19-34
θ-2θ
25, 15-23
ω-2θ
whole data
hemisphere
3-52
θ-ω
2θ range, deg
3-50
14,30,20
8.84
3-50
6-47
h,k,l range
(49,(12,(23
7.85
(18,(19,26
4.75
13,19,(14
13.76
(13,(28,(15
31.83
µ(Mo KR), cm-1
cryst size, mm
temp, K
0.48 × 0.40 × 0.35
0.5 × 0.5 × 0.5
0.50 × 0.50 × 0.60
0.25 × 0.30 × 0.33 0.52 × 0.44 × 0.36
296
298
298
297
296
no. of measd rflns
no. of unique rflns
no. of obst rflns (No)
42 104
8449
7104 (>3σ)
0.038, 0.043
1.22
4428
2098
1660 (>4σ)
0.041, 0.050
8198
8173
6711 (>2σ)
0.026, 0.030
1.64
4501
4269
3400 (>3σ)
0.027, 0.034
1.27
14 136
5446
4754 (>3σ)
0.034, 0.042
1.01
Ra, Rw
a
GOFa
1.04
refinement program
no. of ref params (Np) 560
SHELXTL-PLUS
SHELXTL-PLUS
NRCVAX
560
TEXSAN
289
SHELXTL-PLUS
308
2 -1
138
[σ2(Fo) + 0.0006Fo
0
1.12
-0.65
]
[σ2(Fo) + 0.0010Fo
]
[σ2(Fo) + 0.0001Fo
1.91(15) × 10-4
0.0065
]
[σ2(Fo)]-1
[σ2(Fo) + 0.0009Fo
]
2
-1
2
-1
2
-1
weighting scheme
second extinct coeff
(∆F)max, e Å-3
0
0.89
-0.63
0.32
-0.56
0.97
-0.70
(∆F)min, e Å-3
-0.53
a
2
R ) [∑||Fo| - |Fc||/∑|Fo]. Rw ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2. GOF ) [∑w(|Fo| - |Fc|)2/(No - Np)]1/2
.
[Ru 2(CO)4(µ-SiP r )2I2(P P h 3)2] (8): 83% yield. Anal. Calcd
for C46H44I2O4P2Ru2S2: C, 44.45; H, 3.57. Found: C, 44.21;
H, 3.60. 1H NMR (27 °C, acetone-d6, 400 MHz): δ 0.95 (d, 12
H, J ) 6.7), 2.99 (h, 2 H), 7.60 (m, 30 H). 31P{1H} NMR (300
or 220 K, acetone-d6, 162 MHz): δ 46.65 (s, 2 P). IR (CH2-
vacuum to afford 148 mg of the product [Ru2(CO)4(µ-SPh)2-
(SPh)2(PPh3)2] (11) in 75% yield. Anal. Calcd for
C
64H50O4P2Ru2S4: C, 60.27; H, 3.95. Found: C, 60.17; H, 3.95.
IR (CH2Cl2): vCO, 2045 s, 2032 sh, 1985 s cm-1 1H NMR (27
.
°C, CDCl3, 400 MHz): δ 7.39 (m, 50 H). 31P{1H} NMR (300
K, CDCl3, 162 MHz): δ 19.47 (s, 2 P).
Cl2): vCO, 2059 s, 2051 s, 2005 s cm-1
.
Sin gle-Cr ysta l X-r a y Diffr a ction Stu d ies of 3, 4A, 5B,
6, a n d 10. Suitable single crystals were grown from CH2Cl2/
MeOH or CH2Cl2/hexane at room temperature and chosen for
single crystal structure determinations. The X-ray diffraction
data of 4A, 5B, and 6 were measured on a four-circle diffrac-
tometer, and those of 3 and 10 were measured in frames with
increasing ω (0.3 deg/frame) and with the scan speed at 10.00
s/frame on a Siemens SMART-CCD instrument, equipped with
a normal focus and 3 kW sealed-tube X-ray source. For data
collected on the four-circle diffractometer, three standard
reflections were monitored every hour or every 50 reflections
throughout the collection. The variation was less than 2%.
Empirical absorption corrections were carried out based on an
azimuthal scan. For 6, the structure was solved by direct
methods and refined by a full-matrix least-squares procedure
using TEXSAN.7 For 5B, the structures were solved by the
heavy-atom method and refined by a full-matrix least-squares
procedure using NRCVAX.8 For 3, 4A, and 10, the structures
were solved by direct methods and refined by a full-matrix
least-squares procedure using SHELXTL-PLUS.9 Neutral
atom scattering factors for non-hydrogen atoms and the values
for ∆f′ and ∆f′′ described in each software7-9 were used. The
other essential details of single-crystal data measurement and
refinement are listed in Table 1. One molecule of MeOH and
two molecules of H2O were found in the asymmetric unit of
[Ru 2(CO)4(µ-SP h )2I2(P P h 3)2] (9): 85% yield. Anal. Calcd
for C52H40I2O4P2Ru2S2: C, 47.64; H, 3.08. Found: C, 47.43;
H, 3.11. 1H NMR (27 °C, acetone-d6, 400 MHz): δ 7.47 (m, 40
H). 31P{1H} NMR (300 or 220 K, acetone-d6, 162 MHz): δ
50.97 (s, 2 P). IR (CH2Cl2): vCO, 2070 sh, 2062 s, 2017 s cm-1
.
[Ru 2(CO)4(µ-SP h )2I2(P Me3)2] (10): 82% yield. Anal. Calcd
for C22H28I2O4P2Ru2S2: C, 28.16; H, 3.01. Found: C, 28.11;
H, 3.01. 1H NMR (27 °C, acetone-d6, 400 MHz): δ 1.74 (d, 9
H, J ) 10.8), 1.84 (d, 9 H, J ) 10.8), 7.53 (m, 10 H). 31P{1H}
NMR (300 or 220 K, acetone-d6, 162 MHz): δ 18.47 (s, 1 P),
27.77 (s, 1 P). IR (CH2Cl2): vCO, 2047 s, 2008 sh, 1991 s, 1960
m cm-1
.
Rea ction of [Ru 2(CO)4(µ-SR)2I2(P R′3)2] w ith R′′SH (R′′
) tBu , iP r , P h ) a n d Et3N. (a) Reactions between 7 and R′′SH/
t
Et3N and that between 9 and BuSH/Et3N are quite similar,
and only one typical example is shown below. Compound 7
(445 mg, 0.35 mmol) was dissolved in 20 mL of MeCN, and to
this solution were then added 1 mL of PhSH and 2 mL of Et3N.
The solution was stirred for 2 h, forming a orange-yellow
precipitate. The solvent and volatiles were then removed
under vacuum, and the residue was taken up in a minimum
amount of CH2Cl2. The products were separated by thin-layer
chromatography using CH2Cl2/hexane mixed solvents to give
63 mg of PhSSPh (83%) and 274 mg of 3 (77%). (b) Reaction
between 9 and PhSH/Et3N: Compound 9 (203 mg, 0.155 mmol)
was dissolved in 10 mL of MeCN to form a clear yellow
solution, and to this solution were then added 1 mL of Et3N
and 0.5 mL of PhSH. Upon addition of PhSH, the orange-
yellow color developed immediately and an orange-yellow
precipitate appeared within 3 min. The suspension was stirred
for an additional 30 min. The precipitate was collected,
washed with 5 mL of MeOH three times, and dried under
(7) Crystal Structure Analysis Package, Molecular Structure Cor-
poration, Texas, 1985 and 1992.
(8) Gabe, E. J .; Le page, Y.; Charland, J .-P.; Lee, F. L.; White, P. S.
J . Appl. Crystallogr. 1989, 22, 384.
(9) (a) Sheldrick, G. M. SHELXTL-Plus Crystallographic System,
release 4.21; Siemens Analytical X-ray Instruments: Madison, WI,
1991. (b) Siemens Analytical X-ray Instruments Inc.: Karlsruhe,
Germany, 1991.

Diruthenium Thiolato-Bridged Complexes
Organometallics, Vol. 17, No. 9, 1998 1793
Sch em e 1
F igu r e 1. ORTEP plot of [Ru2(CO)4(µ-StBu)2(PPh3)2] (3).
Selected bond distances (Å): Ru(1)-Ru(2) ) 2.640(1), Ru-
(1)-S(1) ) 2.319(1), Ru(1)-S(2) ) 2.422(1), Ru(1)-P(1) )
2.449(1), Ru(1)-C(1) ) 1.867(4), Ru(1)-C(2) ) 1.867(5),
Ru(2)-S(1) ) 2.564(1), Ru(2)-S(2) ) 2.466(1), Ru(2)-P(2)
) 2.265(1), Ru(2)-C(3) ) 1.887(4), Ru(2)-C(4) ) 1.945(5).
Selected bond angles (deg): Ru(1)-Ru(2)-S(1) ) 52.9(1),
Ru(1)-Ru(2)-S(2) ) 56.5(1), Ru(1)-Ru(2)-P(2) ) 148.6-
(1), Ru(2)-Ru(1)-S(1) ) 61.9(1), Ru(2)-Ru(1)-S(2) ) 58.1-
(1), Ru(2)-Ru(1)-P(1) ) 150.3(1), Ru(1)-S(1)-Ru(2) )
65.2(1), Ru(1)-S(2)-Ru(2) ) 65.4(1), P(1)-Ru(1)-S(1) )
96.6(1), P(1)-Ru(1)-S(2) ) 97.9(1), P(2)-Ru(2)-S(1) )
100.8(1), P(2)-Ru(2)-S(2) ) 100.6(1).
the crystals used for 3. The solvent hydrogen positions in this
structure were not included in the structure refinement.
in acetone-d6, or at 420 K in acetophenone-d3, indicating
probably the presence of only one isomer at either high
or low temperature. On the basis of the three-carbonyl-
stretching-band pattern observed for 3 dissolved in CH2-
Cl2, the structure is not in the anti form (Cs symmetry),
but in the syn geometry (C2v symmetry), which was
confirmed by X-ray diffraction methods (Figure 1). The
high-temperature 31P NMR evidence reflects that the
syn geometry is more stable thermodynamically than
the anti form, if this form can be prepared in some way.
It is hence quite surprising that Ros’s isolated “syn”
isomer was found to be a minor product with “syn”/“anti”
) 1:8.5c
The isolated 4 and 5 exist in solution as equilibrium
mixtures of syn ( isomer A) and anti (isomer B) isomers,
as evidenced by the following: (1) similar NMR and IR
spectra were obtained by dissolving either the products
4 and 5 or their single crystals (4A and 5B); (2) the syn:
anti ratio was found to be changeless within experi-
mental error, even after a toluene solution of 4 (or 5)
was heated under reflux for more than 80 h; and (3)
Resu lts a n d Discu ssion
Syn th esis, Str u ctu r es, a n d Solu tion Beh a vior of
[Ru 2(CO)4(µ-SR)2(P R′3)2] (3-6). Following one of our
recent reports that the acetonitrile ligands of 1 and 2
- 10
can be easily replaced by weak anions such as NO3
,
we rediscovered that the temperature for reaction
between 1 and 1,2-benzenedithiol to produce [Ru2(CO)4-
(µ,η2-S2C6H4)(PPh3)2]5b can be reduced to the ambient
temperature. Likewise the reaction of 1 and 2 with a
thiol in the presence of a base such as Et3N can occur
readily at ambient temperature to give 3-6 in satisfac-
tory yield (Scheme 1). The diruthenium trimethylphos-
phine derivative was found to be more air-sensitive than
the triphenylphosphine analogue. Both the thiol and
Et3N should be carefully deaerated before addition to
compounds 1 and 2, especially for the preparation of 6.
This compound is orange-yellow. However, when aer-
ated thiol and Et3N were used to react with 2, the
resulted orange-red to red products contained obviously
multiple components displaying more than 15 31P{1H}
NMR singlets between δ -20 and 33 in CDCl3.
two exchange cross peaks, indicating clearly Psyn T Panti
,
were shown in the 31P{1H} NOESY NMR experiments11
for 4 and 5 in CDCl3 at 298 K. The spectral data
support that 4A (the syn form) is the major isomer for
4, whereas 5B (the anti form) is the major component
for 5. The observed syn/anti (or 4A:4B) integration ratio
Compound 3 was previously reported to be formed
either from the thermal degradation of [Ru3(CO)9(PPh3)3]
t
with BuSH by Cabeza et al. in 19895a or from a long
1
of 1.16:1 based on the H NMR doublets assigned for
(20 h) thermal displacement reaction between
[Ru2(CO)4(µ-O2CH)2(PPh3)2] and the thiol in refluxing
toluene (bp 110 °C) by Ros et al. in 1995.5c Although it
is not unreasonable that both syn and anti isomers are
produced under these reaction conditions, the 31P{1H}
chemical shifts of Ros’s two isomers are rather high at
δ 45.3 for syn and 39.5 for anti, compared with the
values of 23.87 reported for Cabeza’s compound5a and
17.78 measured for 3 in our laboratory. The 31P{1H}
singlet observed for this compound remains at 220 K
i
the methyl groups of Pr of 4 is close to that of 1.14:1
based on the inverse-gated 31P{1H} NMR singlets (i.e.,
without NOE) in CDCl3. Similarly, the calculated
integration ratio between one carbonyl 13C NMR singlet
for 5A (the syn form) and two carbonyl singlets for 5B
(the anti form) is 1.14:1:1, based on the observed 5A:
5B integration ratio of 1:1.766 found as two inverse-
gated 31P{1H} NMR singlets, is close to the observed
integration ratio of 1.13:1:1 based on the three broad
(10) Shiu, K.-B.; Yang, L.-T.; J ean, S.-W.; Li, C.-H.; Wu, R.-L.; Wang,
J .-C.; Liou, L.-S.; Chiang, M. Y. Inorg. Chem. 1996, 35, 7845.
(11) Bodenhausen, G.; Ernst, R. R. J . Am. Chem. Soc. 1982, 104,
1304.

1794 Organometallics, Vol. 17, No. 9, 1998
Shiu et al.
previously reported in obtaining one “syn” and two
“anti” isomers of a similar compound, [Ru2(CO)4(µ-SBz)2-
(PPh3)2] (Bz ) benzyl), by Ros’s group.5c The syn-anti
equilibria of the organothio-bridged deriviatives of iron
carbonyl, [Fe2(CO)6(µ-SR)2] (with R ) Me, Et), and of
their monosubstitution products, [Fe2(CO)5(µ-SMe)2(Pn-
Bu3)], were reported previously to have the predominant
form in anti geometry for the former but in syn
geometry for the latter.4e The disubstitution products
of a related selenium compound, [Ru2(CO)6(µ-SePh)2],
with PPh3 were also found to consist of both forms, with
the anti mode favored.6 Apparently both steric and
electronic factors should be combined to account for the
different ratio between the two forms.4g,h
Dinuclear thiolato-bridged phosphine carbonyl com-
plexes [M2(CO)4(µ-SR′)2(PR3)2] (M ) Fe, Ru) were rarely
characterized by X-ray diffraction methods and limited
in the syn form of [Fe2(CO)4(µ-SMe)2(PMe3)2] in 1977,4i
and no crystal structures containing diruthenium ana-
logues have been characterized so far. Hence, 3, 4A,
and 5B are the first crystallographically characterized
syn and anti structures of diruthenium thiolato-bridged
carbonyl phosphine complexes. The Ru-Ru distances
of 2.640(1) Å in 3, 2.694(1) Å in 4A, and 2.679(1) Å in
5B are similar to each other and fall within the range
2.558-2.873 Å of other singly Ru-Ru bonded complexes
with ligation of PPh3 ligands.10,12 Structure 4A has a
crystallographically imposed mirror plane containing
the midpoint of the Ru-Ru bond, two sulfur atoms, and
four carbon atoms, C(3)-C(6) (Figure 2). Like the
previously reported structure with two thiolato bridges,
[Fe2(CO)4(µ-SMe)2(PMe3)2],4i and those with one dithi-
olato bridge, [Ru2(CO)4(µ,η2-S2(C6H4)(PPh3)2]5b and [Ru2-
(CO)4(µ,η2-S2(CH2)3)(PPh3)2],5c the three thiolato-bridged
structures 3 (Figure 1), 4A (Figure 2), and 5B (Figure
3) follow to have a common structure type with the two
thiolato bridges all being located cis to the two phos-
phine groups.
Like 4 and 5, product 6 exhibited two 31P{1H} NMR
singlets at δ 6.42 and 15.17 at ambient temperature
(298 K) and at a low temperature (220 K). However,
the single-crystal X-ray structure evidence of 6 did not
support the presence of both syn and anti isomers in
solution, but revealed an unprecedented structure type
for only one anti isomer. The two thiolato bridges are
located cis to one but trans to the other phosphine
ligand, resulting in two inequivalent phosphine atoms
and two 31P{1H} NMR singlets in the NMR spectra, with
d(Ru-Ru) ) 2.6923(8) Å in 6 (Figure 4). The four-band
vCO pattern displayed by a CH2Cl2 solution of 6 in an
IR spectrum is consistent with the C1 symmetry of this
structure. However, the vCO pattern should not be
overemphasized without consideration of other evidence
such as NMR results in the characterization of the
related structures, for the bands may be overlapped into
a different pattern or may not be resolved by the IR
instrument, explaining a six-band and a three-band
pattern observed for 4 and 5, respectively, each contain-
ing an equilibrium mixture of two differently weighted
F igu r e 2. ORTEP plot of [Ru2(CO)4(µ-SiPr)2(PPh3)2] (4A).
Selected bond distances (Å): Ru(1)-Ru(1a) ) 2.694(1), Ru-
(1)-S(1) ) 2.424(3), Ru(1)-S(2) ) 2.422(3), Ru(1)-P(1) )
2.375(3), Ru(1)-C(1) ) 1.874(10), Ru(1)-C(2) ) 1.855(10).
Selected bond angles (deg): Ru(1a)-Ru(1)-S(1) ) 56.3-
(1), Ru(1a)-Ru(1)-S(2) ) 56.2(1), Ru(1a)-Ru(1)-P(1) )
148.7(1), Ru(1)-S(1)-Ru(1a) ) 67.5(1), P(1)-Ru(1)-S(1)
) 97.5(1), P(1)-Ru(1)-S(2) ) 102.6(1).
F igu r e 3. ORTEP plot of [Ru2(CO)4(µ-SPh)2(PPh3)2] (5B).
Selected bond distances (Å): Ru(1)-Ru(2) ) 2.6788(10),
Ru(1)-S(1) ) 2.4285(9), Ru(1)-S(2) ) 2.4358(11), Ru(1)-
P(1) ) 2.3897(11), Ru(1)-C(1) ) 1.868(3), Ru(1)-C(2) )
1.861(3), Ru(2)-S(1) ) 2.4260(8), Ru(2)-S(2) ) 2.4323(9),
Ru(2)-P(2) ) 2.3762(11), Ru(2)-C(3) ) 1.874(3), Ru(2)-
C(4) ) 1.870(3). Selected bond angles (deg): Ru(2)-Ru-
(1)-S(1) ) 51.463(24), Ru(2)-Ru(1)-S(2) ) 56.55(3), Ru-
(2)-Ru(1)-P(1) ) 159.917(24), Ru(1)-Ru(2)-S(1) ) 56.55(3),
Ru(1)-Ru(2)-S(2) ) 56.68(3), Ru(1)-Ru(2)-P(2) ) 156.929-
(24), Ru(1)-S(1)-Ru(2) ) 66.98(3), Ru(1)-S(2)-Ru(2) )
66.77(3), P(1)-Ru(1)-S(1) ) 109.04(4), P(1)-Ru(1)-S(2)
) 109.96(4), P(2)-Ru(2)-S(1) ) 106.57(4), P(2)-Ru(2)-
S(2) ) 107.81(4).
13C NMR carbonyl singlets measured in CDCl3. Both
the 31P{1H} NMR singlet and the 13C NMR carbonyl
singlet for the syn form were observed at an upfield
position relative to those for the anti form (31P{1H} NMR
δ 19.97 for 4A vs 26.54 for 4B and 21.98 for 5A vs. 26.15
for 5B; 13C{1H} NMR 202.0 for 5A vs 203.4 and 204.6
for 5B). The single-crystal structures were determined
by X-ray diffraction methods, confirming the stereo-
chemistry with the syn form for 4A (Figure 2) and the
anti form for 5B (Figure 3). Quite coincidentally, the
major isomer is the one giving the structures. The
spectral and the X-ray crystal structural evidence
apparently explain why the two isomers of 4 and 5
cannot be separated in our hands by either silica or
alumina column chromatography by CH2Cl2/hexane
mixtures, although such a separation method was
(12) (a) Sherlock, S. J .; Cowie, M.; Singleton, E.; Steyn, M. M. de V.
J . Organomet. Chem. 1989, 361, 353. (b) Garcia-Granda, S.; Obeso-
Rosete, R.; Gonzalez, J . M. R.; Anillo, A. Acta Crystallogr. 1990, C46,
2043. (c) Shiu, K.-B.; Peng, S.-M.; Cheng, M.-C. J . Organomet. Chem.
1993, 452, 143. (d) Klemperer, W. G.; Bianxia, Z. Inorg. Chem. 1993,
32, 5821.

Diruthenium Thiolato-Bridged Complexes
Organometallics, Vol. 17, No. 9, 1998 1795
F igu r e 5. ORTEP plot of [Ru2(CO)4(µ-SPh)2I2(PMe3)2] (10).
Selected bond distances (Å): Ru(1)-I(1) ) 2.799(1), Ru-
(1)-S(1) ) 2.466(1), Ru(1)-S(2) ) 2.458(1), Ru(1)-P(1) )
2.337(1), Ru(1)-C(1) ) 1.886(6), Ru(1)-C(2) ) 1.869(6),
Ru(2)-S(1) ) 2.471(1), Ru(2)-S(2) ) 2.463(1), Ru(2)-P(2)
) 2.360(1), Ru(2)-C(3) ) 1.865(9), Ru(2)-C(4) ) 1.859(7).
Selected bond angles (deg): I(1)-Ru(1)-P(1) ) 171.6(1),
I(2)-Ru(2)-C(4) ) 172.7(2), Ru(1)-S(1)-Ru(2) ) 98.6(1),
Ru(1)-S(2)-Ru(2) ) 99.1(1), P(1)-Ru(1)-S(1) ) 91.5(1),
P(1)-Ru(1)-S(2) ) 90.2(1), P(2)-Ru(2)-S(1) ) 94.5(1),
P(2)-Ru(2)-S(2) ) 168.3(1).
F igu r e 4. ORTEP plot of [Ru2(CO)4(µ-SPh)2(PMe3)2] (6).
Selected bond distances: Ru(1)-Ru(2) ) 2.6923(8), Ru(1)-
S(1) ) 2.423(1), Ru(1)-S(2) ) 2.433(1), Ru(1)-P(1) ) 2.357-
(1), Ru(1)-C(1) ) 1.862(4), Ru(1)-C(2) ) 1.868(5), Ru(2)-
S(1) ) 2.417(1), Ru(2)-S(2) ) 2.407(1), Ru(2)-P(2) )
2.327(1), Ru(2)-C(3) ) 1.891(4), Ru(2)-C(4) ) 1.880(5) Å.
Selected bond angles: Ru(2)-Ru(1)-S(1) ) 56.09(3), Ru-
(2)-Ru(1)-S(1) ) 55.76(3), Ru(2)-Ru(1)-P(1) ) 151.95-
(3), Ru(1)-Ru(2)-S(1) ) 56.32(3), Ru(1)-Ru(2)-S(2) )
56.65(3), Ru(1)-Ru(2)-P(2) ) 102.74(3), Ru(1)-S(1)-Ru-
(2) ) 67.60(3), Ru(1)-S(2)-Ru(2) ) 67.60(3), P(1)-Ru(1)-
S(1) ) 99.71(4), P(1)-Ru(1)-S(2) ) 109.13(4), P(2)-Ru(2)-
S(1) ) 159.04(4), P(2)-Ru(2)-S(2) ) 90.81(4)o.
Sch em e 3
Sch em e 2
syn and anti isomers. A mechanism probably involving
conversion of a bridging into a terminal thiolato group
with concomitant formation of multiple Ru-Ru bonding
interactions is proposed to account for the equilibrium
process between the syn and anti forms of 4 and 5 in
solution (Scheme 2).
Syn th esis, Str u ctu r es, a n d Rea ction s of [Ru 2-
(CO)4(µ-SR′)2I2(P R3)2] (7-10). The electrophilic ad-
dition of I2 to CH2Cl2 solutions of 3-6 generates almost
immediately at ambient temperature the diiodide ad-
ducts [Ru2(CO)4(µ-SR′)2I2(PR3)2] (7-10) (Scheme 3). It
appears that there are two different classes of products,
as shown in the three-band and the four-band vCO
patterns observed for 7-9 and 10, respectively. Quite
coincidentally, the difference between the highest vCO
bands of 7-10 and their respective precursor com-
pounds 3-6 is as high as about 50 cm-1 for 7-9 and as
low as 4 cm-1 for 10 (2057 in 7 vs 2001 in 3; 2059 in 8
vs 2001 in 4; 2070 in 9 vs 2016 in 4; 2047 in 10 vs 2043
cm-1 in 6). The single crystals of 10 were easily grown
from CH2Cl2/hexane at ambient temperature, and the
structure was soon found to keep the unique structure
just like the precursor 6 but change the geometry from
anti in 6 into syn in 10 (Figure 5). This novel structure
with inequivalent phosphine atoms remains not only in
the solid state but also in solution, as shown with two
observed 31P{1H} NMR singlets at δ 18.47 and 27.77 in
acetone-d6 at 300 and 220 K. The long distance with
d(Ru‚‚‚Ru) ) 3.743 Å between two Ru atoms indicates
no Ru-Ru single bond in 10 and probably also in 7-9.
The two iodides are trans to each other, reflecting a
trans addition of diiodine to 6 and probably also to 3-5.
If the resulting structure 7-9 has two trans iodide
atoms with each at one Ru atom, the observed 31P{1H}
NMR singlet at δ 44.58 for 7, 46.65 for 8, and 50.97 for
9 in acetone-d6 at 300 and 220 K may suggest a very
facile process, probably involving conversion of two
terminal into bridging iodides concomitantly with open-
ing two bridging into terminal thiolato groups while not
permitting rotation of two carbonyls and one phosphine
attached to each Ru atom along a pseudo-C3 axis
(Scheme 4), resulting in two equivalent and inequivalent
phosphine atoms for 7-9 and 10, respectively, at the
NMR time scale. The evidence of the three-band vCO
pattern and the one 31P{1H} NMR singlet described for

1796 Organometallics, Vol. 17, No. 9, 1998
Shiu et al.
Sch em e 4
Sch em e 5
1
7-9 and that of one H NMR singlet at δ 0.76 for the
two tBu groups in 7, one doublet at 0.95 and one heptet
at 2.99 for two iPr groups in 8, and one 31C NMR doublet
at 192.5 with J P,C ) 11.0 Hz13 for the four carbonyl
groups in 9 suggest that 7-9 should adopt probably the
syn form rather than the anti form.
The reported reaction chemistry of [Fe2(CO)4(µ-SR)2-
(PPh3)2] (R ) Et, Ph) with X2 (X ) Cl, Br, I) is quite
rich, producing either [Fe2(CO)4(µ-SR)2(PPh3)2I]I3 or
[Fe3(CO)4(µ-SR)2(PPh3)2X4]X with no Fe-Fe metal bond.4b
However, decarbonylation occurs quite readily for iodi-
nation of 7-9, resulting in intractable products, appar-
ently without carbonyl groups attached to the metal
center on the basis of the IR spectra obtained. Reactions
of 7-9 with nucleophiles such as thiolate anions were
then carried out. The reaction results between com-
t
Cl2 at 300 or 220 K, suggesting a similar facile process
involving conversion of two terminal into bridging
thiolato groups concomitantly with opening two bridging
into terminal thiolato groups (cf. Scheme 4) to make two
phosphine atoms equivalent at the NMR time scale.
However, the two structures are different, with a syn
form for 9 and an anti form for 11, based on the two
observed 13C NMR doublets at δ197.2 (J ) 8.3 Hz)13 and
197.5 (J ) 9.7 Hz)13 for the four carbonyls in this
compound dissolved in CDCl3. Apparently, it is rather
difficult to predict the structure preference for any
diruthenium compounds with two thiolato bridges prior
to examining the characterization data. The two thi-
olato bridges in a dinuclear system may adopt a syn
form like 3 and 7-10 or an anti form like 6 and 11, or
they may involve an equilibrium mixture of syn and anti
forms with the syn form favored for 4 and the anti form
for 5 in solution. This nonspecific feature is probably
more associated with steric effects than electronic
effects, and the one or two forms adopted may represent
nonbonded interactions of low, if not the least, repul-
siveness.
plexes 7 and 9 and the anions via R′′SH/Et3N (R′′ ) -
Bu, iPr, Ph) appear somewhat unexpectedly to have two
reaction pathways. Among the five reactions studied,
only the one between 9 and PhS- gave the expected
substitution product, [Ru2(CO)4(µ-SPh)2(SPh)2(PPh3)2]
(11). Other reactions regenerated reductively 3 and 5
with the apparently external R′′S anions being oxidized
into R′′SSR′′ in high yield (Scheme 3). Disulfide forma-
tion was previously reported for the internally ligated
thiolato groups of [Fe2(CO)6(µ-SR)2] but under oxidation
conditions with O2,4j different from our examples.
Under similar reaction conditions with excess R′′SH/
Et3N relative to the complex (e.g., 1 mL of R′′SH, 2 mL
of Et3N, and ca. 0.30 mmol of the complex), we found
that the time required for a complete redox reaction is
ca. 2 h, much longer than that of 0.5 h needed for a
complete substitution reaction. Further, on the basis
of the IR spectra measured sequentially for the longer
redox reaction, no intermediate compounds were ob-
served with typical IR spectra recorded in an overlaid
mode for the reaction between 7 and PhSH/Et3N in CH2-
Cl2. These facts led us to propose a mechanism favoring
substitution (route a) rather than a redox process (route
b) for the first step of the reaction.15 It probably involves
the replacement of one iodide at the less sterically
congested site (cf. Scheme 5) with one thiolate anion to
form the intermediate [Ru2(CO)4(µ-SR)2(SR′′)I(PR′3)2].
For PhS-, the steric hindrance of this intermediate with
R ) R′ ) R′′ ) Ph is not large, enabling a further
replacement reaction (route c) to give 11. However,
when the hindrance of the intermediate with one of the
other combinations of R, R′, and R′′ (i.e., R ) R′ ) Ph,
Con clu sion
Our investigation into diruthenium carbonyl phos-
phine complexes containing two µ-thiolato linkages
resulted in the facile synthesis of 3-6 from 1 and 2 in
satisfactory yield (Scheme 1). Electrophilic additions
of 3-6 with I2 produce diiodide adducts 7-10. Further
reactions of 7 and 9 with thiolate anions give either
expected nucleophilic substitution products such as 11
or unexpected reductive-dehalogenation to regenerate
complexes 3 and 5, respectively, with the apparently
external anions being oxidized into alkyl or aryl disul-
fides (Scheme 3). Various spectral data and five X-ray
crystal structures (Figures 1-5) help to establish that
the two thiolato bridges in 3-11 may adopt a syn form
or an anti form, or they may involve an equilibrium
mixture of both forms with one form or the other favored
in solution. An unprecedented structure type with the
two thiolato bridges located cis to one of two phosphine
ligands in the compounds but trans to the other was
t
t
i
t
R′′ ) Bu; or R ) Ph, R′ ) Bu, R′′ ) Ph, Pr, or Bu) is
too high to allow a second replacement reaction, a redox
reaction (route d) occurs with regeneration of complexes
3 and 5 and R′′SSR′′.
Like 9, 11 displays one 31P{1H} NMR singlet for the
two PPh3 ligands in this compound dissolved in CH2-
(13) The coupling constant is compatible with the reported values.14
(14) Gill, D. F.; Mann, B. E.; Shaw, B. L. J . Chem. Soc., Dalton
Trans. 1973, 311.
(15) Astruc, D., Ed. Electron Transfer and Radical Processes in
Transition-Metal Chemistry; VCH: New York, 1995.

Diruthenium Thiolato-Bridged Complexes
Organometallics, Vol. 17, No. 9, 1998 1797
Su p p or t in g In for m a t ion Ava ila b le: Tables of non-
hydrogen atomic coordinates and equivalent isotropic displace-
ment coefficients, complete bond lengths and angles, aniso-
tropic displacement coefficients, and hydrogen coordinates for
3, 4A, 5B, 6, and 10 (30 pages). Ordering information is given
on any current masthead page.
observed in 6 (Figure 4) and retained in the iodination
product 10 (Figure 5), in spite of the anti geometry in 6
being changed into syn in 10.
Ack n ow led gm en t. Financial support for this work
by the National Science Council of Republic of China
(Contract NSC87-2113-M006-007) and skillful assis-
tance by Ms. Fang-Chung Chou are gratefully acknowl-
edged.
OM9710024