Unusual reactions of cationic bridging carbyne complexes of dimethylsilane-bridged bis(η5-cyclopentadienyl)diiron tricarbonyl with nucleophiles. A route to iron-sulfur cluster bridging carbene complexes

Article abstract of DOI:10.1021/om010322r

The reactions of diiron cationic carbyne complexes [Fe₂(μ-CO)(μ-CAr)(CO)₂{(η⁵- C₅H₄)₂Si-(CH₃)₂}] BBr₄ (4, Ar = C₆H₅; 5, Ar = p-CH₃C₆H₄; 6, Ar = p-CF₃C₆H₄) with NaSR (R = CH₃, C₆H₅, p-CH₃C₆H₄) in THF at low temperature afford diiron bridging mercaptocarbene complexes [Fe₂(μ-CO){μ-C(SR)Ar}(CO)₂{(η⁵- C₅H₄)₂ Si(CH₃)₂}] (9, Ar = C₆H₅, R = CH₃; 10, Ar = C₆H₅, R = C₆H₅, 11, Ar = C₆H₅, R = p-CH₃C₆H₄; 12, Ar = p-CH₃C₆H₄, R = CH₃; 13, Ar = p-CH₃C₆H₄, R = C₆H₅; 14, Ar = p-CH₃C₆H₄, R = p-CH₃C₆H₄; 15, Ar = p-CF₃C₆H₄, R = CH₃; 16, Ar= p-CF₃C₆H₄, R = C₆H₅; 17, Ar = p-CF₃C₆H₄, R = p-CH₃C₆H₄. Compound 6 reacts with [(μ-SLi)(μ-SC₆H₅)Fe₂(CO)₆] to give the novel iron-sulfur cluster bridging carbene complex [Fe₂(μ-CO)(μ-CC₆H₄CF₃-p) (CO)₂{(η⁵- C₅H₄)₂)Si(CH₃)₂}(μ-S) (μ-SC₆H₅)Fe₂(CO)₆] (18). Analogous iron-sulfur cluster bridging carbene complexes [Fe₂(μ-CO)(μ-CAr)(CO)₂(η⁵- C₅H₅)₂- (μ-S)(μ-SC₆H₅)Fe₂(CO)₆] (19, Ar = C₆H₅; 20, Ar = p-CH₃C₆H₄) can also be obtained by the reactions of diiron cationic carbyne complexes [Fe₂(μ-CO)(μ-CAr)(CO)₂(η⁵- C₅H₅)₂]BBr₄ (7, Ar = C₆H₅; 8, Ar = p-CH₃C₆H₄) with [(μ-SLi)(μ-SC₆H₅)Fe₂ (CO)₆]. The structures of complexes 9, 13, 16, and 18 have been established by X-ray crystallography.

Full text of DOI:10.1021/om010322r

4092
Organometallics 2001, 20, 4092-4099
Un u su a l Rea ction s of Ca tion ic Br id gin g Ca r byn e
Com p lexes of Dim eth ylsila n e-Br id ged
Bis(η5-cyclop en ta d ien yl)d iir on Tr ica r bon yl w ith
Nu cleop h iles. A Rou te to Ir on -Su lfu r Clu ster Br id gin g
Ca r ben e Com p lexes
Ruitao Wang,† Qiang Xu,*,‡ J ie Sun,† Li-Cheng Song,*,§ and J iabi Chen*,†
Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry,
Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China,
National Institute of Advanced Industrial Science and Technology, AIST,
1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, J apan, and Department of Chemistry,
State Key Laboratory of Elemento-Organic Chemistry, Nankai University,
Tianjin 300071, China
Received April 17, 2001
The reactions of diiron cationic carbyne complexes [Fe2(µ-CO)(µ-CAr)(CO)2{(η5-C5H4)2Si-
(CH3)2}]BBr4 (4, Ar ) C6H5; 5, Ar ) p-CH3C6H4; 6, Ar ) p-CF3C6H4) with NaSR (R ) CH3,
C6H5, p-CH3C6H4) in THF at low temperature afford diiron bridging mercaptocarbene
complexes [Fe2(µ-CO){µ-C(SR)Ar}(CO)2{(η5-C5H4)2Si(CH3)2}] (9, Ar ) C6H5, R ) CH3; 10,
Ar ) C6H5, R ) C6H5; 11, Ar ) C6H5, R ) p-CH3C6H4; 12, Ar ) p-CH3C6H4, R ) CH3; 13, Ar
) p-CH3C6H4, R ) C6H5; 14, Ar ) p-CH3C6H4, R ) p-CH3C6H4; 15, Ar ) p-CF3C6H4, R )
CH3; 16, Ar) p-CF3C6H4, R ) C6H5; 17, Ar ) p-CF3C6H4, R ) p-CH3C6H4). Compound 6
reacts with [(µ-SLi)(µ-SC6H5)Fe2(CO)6] to give the novel iron-sulfur cluster bridging carbene
complex [Fe2(µ-CO)(µ-CC6H4CF3-p)(CO)2{(η5-C5H4)2Si(CH3)2}(µ-S)(µ-SC6H5)Fe2(CO)6] (18).
Analogous iron-sulfur cluster bridging carbene complexes [Fe2(µ-CO)(µ-CAr)(CO)2(η5-C5H5)2-
(µ-S)(µ-SC6H5)Fe2(CO)6] (19, Ar ) C6H5; 20, Ar ) p-CH3C6H4) can also be obtained by the
reactions of diiron cationic carbyne complexes [Fe2(µ-CO)(µ-CAr)(CO)2(η5-C5H5)2]BBr4 (7, Ar
) C6H5; 8, Ar ) p-CH3C6H4) with [(µ-SLi)(µ-SC6H5)Fe2(CO)6]. The structures of complexes
9, 13, 16, and 18 have been established by X-ray crystallography.
In tr od u ction
Most recently, we found a new method for the prepara-
tion of dimetal bridging carbene and carbyne com-
plexes: the reactions of highly electrophilic diiron
cationic carbyne complexes [Fe2(µ-CO)(µ-CAr)(CO)2(η5-
C5H5)2]BBr4 (Ar ) C6H5, p-CH3C6H4) with nucleophiles
to give a series of diiron bridging carbene complexes.9,10
This offers a new and useful method for the preparation
and structural modification of dimetal bridging carbene
complexes.
In recent years, our interest in developing the meth-
odologies of the synthesis of transition metal bridging
carbene and carbyne complexes stems from the fact that
many such complexes are themselves metal clusters or
are the precursors of metal cluster complexes, which
have played important roles in many catalytic reac-
tions.1,2 A considerable number of di- or trimetal bridg-
ing carbene and bridging carbyne complexes have been
synthesized by Stone and co-workers3-6 and by us.7,8
In the meantime, we have noted our previously
reported reactions of cationic carbyne complexes [η5-
† Shanghai Institute of Organic Chemistry.
‡ National Institute of Advanced Industrial Science and Technology.
§ Nankai University.
(5) (a) Howard, J . A. K.; Mead, K. A.; Moss, J . R.; Navarro, R.; Stone,
F. G. A.; Woodward, P. J . Chem. Soc., Dalton Trans. 1981, 743. (b)
Hodgson, D.; Howard, J . A. K.; Stone, F. G. A.; Went, M. J . J . Chem.
Soc., Dalton Trans. 1985, 1331.
(1) Suess-Fink, G.; Meister, G. Adv. Organomet. Chem. 1993, 35,
41.
(2) (a) Gladfelter, W. L.; Roesselet, K. J . In The Chemistry of Metal
Cluster Complexes; Shriver, D. F., Kaesz, H. D., Adams, R. D., Eds.;
VCH: Weinheim, Germany, 1990; p 392. (b) Maire, G. In Metal
Clusters in Catalysis; Gates, B. C., Guczi, L., Knoezinger, H., Eds.;
Elsevier: Amsterdam, The Netherlands, 1986; p 509. (c) Dickson, R.
S.; Greaves, B. C. Organometallics 1993, 12, 3249.
(3) Stone, F. G. A. In Advances in Metal Carbene Chemistry;
Schubert, U., Ed.; Kluwer Academic Publishers: Dordrecht, The
Netherlands, 1989; p 11.
(4) (a) Ashworth, T. V.; Howard, J . A. K.; Laguna, M.; Stone, F. G.
A. J . Chem. Soc., Dalton Trans. 1980, 1593. (b) Carriedo, G. A.;
Howard, J . A. K.; Stone, F. G. A. J . Chem. Soc., Dalton Trans. 1984,
1555. (c) Garcia, M. E.; J effery, J . C.; Sherwood, P.; Stone, F. G. A. J .
Chem. Soc., Dalton Trans. 1987, 1209. (d) Busetto, L.; J effery, J . C.;
Mills, R. M.; Stone, F. G. A.; Went, M. J .; Woodward, P. J . Chem. Soc.,
Dalton Trans. 1983, 101.
(6) Pilotti, M. U.; Stone, F. G. A.; Topaloglu, L. J . Chem. Soc., Dalton
Trans. 1991, 1621.
(7) (a) Chen, J .-B.; Yu, Y.; Liu, K.; Wu, G.; Zheng, P.-J . Organo-
metallics 1993, 12, 1213. (b) Yu, Y.; Chen, J .-B.; Chen, J .; Zheng, P.-J .
J . Chem. Soc., Dalton Trans. 1996, 1443.
(8) (a) Tang, Y.-J .; Sun, J .; Chen, J .-B. Organometallics 1999, 18,
4337. (b) Tang, Y.-J .; Sun, J .; Chen, J .-B. J . Chem. Soc., Dalton Trans.
1998, 931. (c) Tang, Y.-J .; Sun, J .; Chen, J .-B. J . Chem. Soc., Dalton
Trans. 1998, 4003. (d) Tang, Y.-J .; Sun, J .; Chen, J .-B. Organometallics
1998, 17, 2945. (e) Tang, Y.-J .; Sun, J .; Chen, J .-B. Organometallics
2000, 19, 72. (f) Tang, Y.-J .; Sun, J .; Chen, J .-B. Organometallics 1999,
18, 2459.
(9) Liu, Y.-J .; Wang, R.-T.; Sun, J .; Chen, J .-B. Organometallics
2000, 19, 3498.
(10) Liu, Y.-J .; Wang, R.-T.; Sun, J .; Chen, J .-B. Organometallics
2000, 19, 3784.
10.1021/om010322r CCC: $20.00 © 2001 American Chemical Society
Publication on Web 09/10/2001

Iron-Sulfur Cluster Bridging Carbene Complexes
Organometallics, Vol. 20, No. 19, 2001 4093
ods. Compounds 1-315 and [Fe2(µ-CO)(µ-CC6H5)(CO)2(η5-C5H5)2]-
BBr4 (7)9 and [Fe2(µ-CO)(µ-CC6H4CH3-p)(CO)2(η5-C5H5)2]BBr4
(8)9 were prepared as previously described.
C5H5(CO)2MtCC6H5]BBr4 (M ) Mn, Re) with the (µ-
phenylthio)(µ-thiolato)hexacarbonyldiiron anion, [(µ-
S)(µ-SC6H5)Fe2(CO)6]-, which afforded novel iron-
sulfur cluster carbene complexes [η5-C5H5(CO)2Md
C(C6H5)(µ-S)(µ-SC6H5)Fe2(CO)6] (M ) Mn, Re).11,12 In
view of the catalytic activity and use in organic synthe-
sis of the iron-sulfur cluster complexes,13,14 we take a
great interest in this type of complex.
IR spectra were measured on a Perkin-Elmer 983G spectro-
photometer. All 1H NMR spectra were recorded at ambient
temperature in acetone-d6 solution with TMS as the internal
reference using a Bruker AM-300 spectrometer. Electron
ionization mass spectra (EIMS) were run on a Hewlett-
Packard 5989A spectrometer. Melting points obtained on
samples in sealed nitrogen-filled capillaries are uncorrected.
P r ep a r a tion of [F e2(µ-CO)(µ-CC6H5)(CO)2{(η5-C5H4)2Si-
(CH3)2}]BBr 4 (4). Following the known preparations of the
analogous cationic carbyne complexes [Fe2(µ-CO)(µ-CAr)(CO)2-
(η5-C5H5)2]BBr4 (Ar ) C6H5, p-CH3C6H4), to a solution of [Fe2(µ-
CO){µ-C(OC2H5)C6H5}(CO)2{(η5-C5H4)2Si(CH3)2}] (1)15 (0.30 g,
0.581 mmol) in 150 mL of ether was added 0.30 mL (3.20
mmol) of BBr3 at -65 °C with vigorous stirring. Immediately
a brown-red solid precipitated from the reaction solution. After
stirring for 10 min at -65 °C, the resulting mixture was
filtered, and the solids were washed with ether (2 × 30 mL)
at -65 °C and then dried under high vacuum at -50 °C to
give 0.40 g (85%, based on 1) of 4 as a brown-red solid: IR
(CH2Cl2) ν(CO) 2041 (s), 2012 (s, br), 1848 (m) cm-1; 1H NMR
(CD3COCD3) δ 8.09-7.92 (m, 5H, C6H5), 6.81 (s, 4H, C5H4),
6.08 (d, 2H, C5H4), 5.45 (d, 2H, C5H4) 3.41 (q, 1H, (CH3CH2)2O),
1.12 (t, 1.5H, (CH3CH2)2O), 0.64 (s, 3H, SiCH3), 0.30 (s, 3H,
SiCH3).
The following complexes were prepared by similar reactions.
[F e2(µ-CO)(µ-CC6H 4CH 3-p )(CO)2{(η5-C5H 4)2Si(CH 3)2}]-
BBr 4 (5): brown-red solid (84% yields); IR (CH2Cl2) ν(CO) 2039
(s), 2018 (br), 1848 (m) cm-1; 1H NMR (CD3COCD3) δ 8.41 (d,
2H, C6H4CH3), 7.76 (d, 2H, C6H4CH3), 6.78 (d, 2H, C5H4), 6.76
(d, 2H, C5H4), 6.03 (d, 2H, C5H4), 5.42 (d, 2H, C5H4), 3.42 (q,
1.5H, (CH3CH2)2O), 2.59 (s, 3H, C6H4CH3), 1.13 (t, 2H, (CH3-
CH2)2O), 0.62(s, 3H, SiCH3), 0.29(s, 3H, SiCH3).
[F e2(µ-CO)(µ-CC6H 4CF 3-p )(CO)2{(η5-C5H 4)2Si(CH 3)2}]-
BBr 4 (6): brown-red solid (87%, yield); IR (CH2Cl2) ν(CO) 2046
(s), 2019 (br, m), 1857 (m) cm-1; 1H NMR (CD3COCD3) δ 8.76
(d, 2H, C6H4CF3), 8.22 (d, 2H, C6H4CF3), 6.88 (s, 4H, C5H4),
6.13(s, 2H, C5H4), 5.53(s, 2H, C5H4), 3.46 (q, 1.5H, (CH3CH2)2O),
1.12 (t, 2H, (CH3CH2)2O), 0.68(s, 3H, SiCH3), 0.33(s, 3H,
SiCH3).
To explore the reactivity of the cationic carbyne
complexes of diiron containing different cyclopentadi-
enyl ligands and the effect of different substituents at
the µ-carbyne carbon on the reactivity of the diiron
cationic carbyne complexes and to further examine the
scope of this preparation of dimetal bridging carbene
and bridging carbyne complexes, we chose (dicyclopen-
tadienyldimethylsilane)diiron bridging alkoxycarbene
complexes [Fe2(µ-CO){µ-C(OC2H5)Ar}(CO)2{(η5-C5H4)2-
Si(CH3)2}] (1, Ar ) C6H5; 2, Ar ) p-CH3C6H4; 3, Ar )
p-CF3C6H4),15 obtained by the reactions of di-µ-carbonyl-
cis-µ-(1-5-η:1′-5′-η-dicyclopentadienyldimethylsilane)-
bis(carbonyliron), [Fe2(µ-CO)2(CO)2{(η5-C5H4)2Si(CH3)2}],
with aryllithium reagents followed by alkylation with
Et3OBF4, as starting materials for the reaction with a
Lewis acid such as BBr3 to form the diiron cationic
bridging carbyne complexes [Fe2(µ-CO)(µ-CAr)(CO)2{(η5-
C5H4)2Si(CH3)2}]BBr4 (4, Ar ) C6H5; 5, Ar ) p-CH3C6H4;
6, Ar ) p-CF3C6H4). The cationic carbyne complexes
4-6 reacted with the nucleophiles involving [(µ-SLi) (µ-
SC6H5) Fe2(CO)6]. For comparison, the reactions of
diiron cationic carbyne complexes [Fe2(µ-CO)(µ-CAr)-
(CO)2(η5-C5H5)2]BBr4 (7, Ar ) C6H5; 8, p-CH3C6H4),
where the cyclopentadienyl ligands are the two non-
bridged cyclopentadienyl groups, with [(µ-SLi)(µ-SC6H5)
Fe2(CO)6] were also made. These reactions produced a
series of novel dimetal bridging carbene complexes.
Herein we report these unusual reactions and the
structural characterizations of the resulting products.
Exp er im en ta l Section
Rea ction of 4 w ith Na SCH3 to Give [F e2(µ-CO){µ-
C(SCH3)C6H5}(CO)2{(η5-C5H4)2Si(CH3)2}] (9). To 0.400 g
(0.494 mmol) of freshly prepared (in situ) 4 dissolved in 60
mL of THF at -80 °C was added 0.041 g (0.581 mmol) of
NaSCH3. The reaction mixture was stirred at -80 to -60 °C
for 1 h, during which time the turbid solution turned clear
deep-red gradually. After stirring at -60 to -20 °C for an
additional 3 h, the resulting solution was evaporated under
high vacuum at -30 °C to dryness and the dark red residue
was chromatographed on an alumina column (1.6 × 15-20
cm) at -25 °C with petroleum ether/CH2Cl2 (10:1) as the
eluant. The red band was eluted and collected. After vacuum
removal of the solvent, the residue was recrystallized from
petroleum ether/CH2Cl2 (15:1) solution at -80 °C to give 0.18
g (70%, based on 4) of purple-red crystals of 9: mp 132-134
All procedures were performed under a dry, oxygen-free N2
atmosphere using standard Schlenk techniques. All solvents
employed were reagent grade and dried by refluxing over
appropriate drying agents and stored over 4 Å molecular sieves
under a N2 atmosphere. The tetrahydrofuran (THF) and
diethyl ether (Et2O) were distilled from sodium benzophenone
ketyl, while petroleum ether (30-60 °C) and CH2Cl2 were
distilled from CaH2. The neutral alumina (Al2O3) used for
chromatography was deoxygenated at room temperature under
high vacuum for 16 h, deactivated with 5% w/w N2-saturated
water, and stored under N2. Compounds NaSCH3 and NaSC6H5
were purchased from Fluka Chemical Co. and Aldrich Chemi-
cal Co., respectively. NaSC6H4CH3-p,16 [(µ-S)2Fe2(CO)6],17 and
[(µ-SLi)(µ-SC6H5)Fe2(CO)6]18 were prepared by literature meth-
°C dec; IR (CH2Cl2) ν(CO) 1982 (s), 1950 (m), 1772 (m) cm-1
;
1H NMR (CD3COCD3) δ 7.47-6.88 (m, 5H, C6H5), 6.15 (s, 2H,
C5H4), 5.78 (s, 2H, C5H4), 5.24 (s, 2H, C5H4), 5.07 (s, 2H, C5H4),
2.03 (s, 3H, SCH3), 0.61 (s, 3H, SiCH3), 0.47 (s, 3H, SiCH3);
MS m/e 490 (M+ - CO), 462 (M+ - 2CO), 434 (M+ - 3CO),
415 (M+ - 2CO - SCH3). Anal. Calcd for C23H22O3SFe2Si: C,
53.30; H, 4.28. Found: C, 52.79; H, 4.38.
The following complexes were prepared by similar reactions.
[F e 2 (µ-C O ){µ-C (S C 6 H 5 )C 6 H 5 }(C O )2 {(η5 -C 5 H 4 )2 S i -
(CH3)2}] (10): red crystals (72% yield); mp 114-116 °C dec;
IR (CH2Cl2) ν(CO) 1983 (vs), 1951 (s), 1772 (s) cm-1; 1H NMR
(CD3COCD3) δ 7.47-6.26 (m, 10H, 2C6H5), 5.69 (s, 2H, C5H4),
5.63 (s, 2H, C5H4), 5.29 (s, 2H, C5H4), 5.22 (s, 2H, C5H4), 5.25
(m, 3H, CH2Cl2), 0.64 (s, 3H, SiCH3), 0.51 (s, 3H, SiCH3); MS
(11) Chen, J .-B.; Lei, G.-X.; Zhang, Z.-Y.; Tang, Y.-Q. Acta Chim.
Sin., Engl. Ed. 1986, 4, 311.
(12) Chen, J .-B.; Lei, G.-X.; Zhang, Z.-Y.; Tang, Y.-Q. Acta Chim.
Sin., Engl. Ed. 1989, 47, 31.
(13) De Beer, J . A.; Haines, R. J .; Greatrex, G.; Greenwood, N. N.
J . Organomet. Chem. 1971, 27, C33.
(14) Nametkim, N. S.; Tyurin, V. D.; Kulina, M. A. J . Organomet.
Chem. 1978, 149, 355.
(15) Wang, R.-T.; Sun, J .; Chen, J .-B. J . Organomet. Chem. 2001,
617-618, 292.
(16) Reid, E. E. Organic Chemistry of Bivalent Sulfur; Chemical
Publishing Co. Inc.: New York, 1958; Vol. 1, p 127.
(17) Seyferth, D.; Henderson, R. S.; Song, L.-C. Organometallics
1982, 1, 125.
(18) Seyferth, D.; Kiwan, A. M. J . Organomet. Chem. 1985, 286, 219.

4094 Organometallics, Vol. 20, No. 19, 2001
Ta ble 1. Cr ysta l Da ta a n d Exp er im en ta l Deta ils for Com p lexes 9, 13, 16, a n d 18
Wang et al.
9‚CH2Cl2
13
16
18‚CH2Cl2
formula
fw
space group
a (Å)
b ( Å)
c (Å)
C25H26O3Cl2SFe2Si
617.22
R-3 (No. 148)
32.849(8)
C29H26O3SFe2Si
594.36
P21/a (No. 14)
14.496(4)
10.066(4)
19.059(6)
C29H23O3F3SFe2Si
648.33
P21/a (No. 14)
14.776(3)
10.203(5)
19.003(7)
C36H25O9Cl2F3S2Fe4Si
1045.07
Pna21 (No. 33)
25.324(5)
16.970(3)
9.4415(19)
90
11.603(3)
R (deg)
â (deg)
106.52(2)
104.97(2)
90
90
γ (deg)
V (Å3)
10843(4)
18
1.701
2666(1)
4
1.481
2767(1)
4
1.556
4057.5(14)
4
1.711
Z
Dcalcd (g /cm3)
F(000)
5688.00
15.89
15; 14.1-19.5
3924
1409 (I > 2.80σ(I))
284
0.8857-1.0000
0.058
0.056
1.42
0.00
0.46
1224.00
12.40
20; 13.6-19.4
3494
1707
325
0.7931-1.0000
0.058
0.050
1.43
0.00
0.47
1320.00
12.16
21; 13.7-16.4
4085
1778 (I > 3.00σ(I))
355
0.8791-1.0557
0.071
0.079
2.21
0.00
0.54
2096
17.32
4.79-29.58
9195
9195
540
0.8290-1.0000
0.0590
0.0707
0.656
0.00
0.347
µ(Mo KR) (cm-1)
orientation reflns: no.; range (2θ) (deg)
no. of unique data, total
with I >2.00σ(I)
no. of params refined
correct. factors, max. min.
Ra
b
Rw
quality of fit indicatorc
max shift/esd. final cycle
largest peak, e-/Å3
minimum peak, e-/Å3
-0.54
-0.44
-0.63
-0.312
a
b
2
R ) ∑|Fo| - |Fc|/∑|Fo|. Rw ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2; w ) I/σ2(|Fo|). c Quality-of-fit ) [∑w(|Fo| - |Fc|)2/(Nobs - Nparams)]1/2
.
m/e 580 (M+), 524 (M+ - 2CO), 496 (M+ - 2CO), 84 (CH2Cl2+).
Anal. Calcd for C28H24O3SFe2Si‚1.5CH2Cl2: C, 50.07; H, 3.85.
Found: C, 49.48; H, 3.77.
°C dec; IR (CH2Cl2) ν(CO) 1983 (s), 1952 (m), 1777 (m) cm-1
;
1H NMR (CD3COCD3) δ 7.66-7.35 (dd, 4H, C6H4CF3), 6.21 (s,
2H, C5H4), 5.64 (s, 2H, C5H4), 5.28 (s, 2H, C5H4), 5.08 (s, 2H,
C5H4), 2.09 (s, 3H, SCH3), 0.62 (s, 3H, SiCH3), 0.49 (s, 3H,
SiCH3); MS m/e 586 (M+), 558 (M+ - CO), 530 (M+ - 2CO),
502 (M+ - 3CO), 455 (M+ - 3CO - SCH3). Anal. Calcd for
[F e2(µ-CO){µ-C(SC6H 4CH 3-p )C6H 5}(CO)2{(η5-C5H 4)2Si-
(CH3)2}] (11): purple-red crystals(75% yield); mp 126-128 °C
1
dec; IR (CH2Cl2) ν(CO) 1983 (vs), 1952 (s), 1772 (s) cm-1; H
C
24H21O3F3SFe2Si: C, 49.17; H, 3.61. Found: C, 49.21; H, 3.76.
[F e2(µ-CO){µ-C(SC6H 5)C6H 4CF 3-p }(CO)2{(η5-C5H 4)2Si-
NMR (CD3COCD3) δ 7.42-6.61 (m, 9H, C6H5 + C6H4CH3-p),
6.22 (s, 2H, C5H4), 5.67 (s, 2H, C5H4), 5.25 (s, 4H, C5H4), 2.23
(s, 3H, C6H4CH3), 0.63 (s, 3H, SiCH3), 0.51 (s, 3H, SiCH3); MS
(CH3)2}] (16): red crystals (73% yield); mp 136-138 °C dec;
IR (CH2Cl2) ν(CO) 1984 (s), 1954 (m), 1779 (m) cm-1; 1H NMR
(CD3COCD3) δ 7.61-7.03 (m, 9H, C6H5 + C6H4CF3), 6.30 (s,
2H, C5H4), 5.76 (s, 2H, C5H4), 5.32 (s, 2H, C5H4), 5.24 (s, 2H,
C5H4), 0.65 (s, 3H, SiCH3), 0.53 (s, 3H, SiCH3); MS m/e 648
(M+), 564 (M+ - 3CO), 539 (M+ - SC6H5). Anal. Calcd for
m/e 594 (M+), 538 (M+ - 2CO), 510 (M+ - 3CO), 471 (M+
-
SC6H4CH3). Anal. Calcd for C29H26O3SFe2Si: C, 58.60; H, 4.41.
Found: C, 58.91; H, 4.45.
[F e2(µ-CO){µ-C(SCH 3)C6H 4CH 3-p }(CO)2{(η5-C5H 4)2Si-
(CH3)2}] (12): purple-red crystals (73% yield); mp 126-127
°C dec; IR (CH2Cl2) ν(CO) 1981 (s), 1949 (m), 1773 (m) cm-1
;
C
29H23O3F3SFe2Si: C, 53.72; H, 3.55. Found: C, 53.73; H, 3.48.
[F e 2(µ-C O ){µ-C (S C 6H 4C H 3-p )C 6H 4C F 3-p }(C O )2{(η5-
1H NMR (CD3COCD3) δ 7.35-6.83 (dd, 4H, C6H4CH3), 6.13
(s, 2H, C5H4), 5.56 (s, 2H, C5H4), 5.22 (s, 2H, C5H4), 5.05 (s,
2H, C5H4), 2.19 (s, 3H, SCH3), 2.03 (s, 3H, C6H4CH3), 0.61 (s,
C5H4)2Si(CH3)2}] (17): purple-red crystals (78% yield); mp
119-121 °C dec; IR (CH2Cl2) ν(CO) 1983 (s), 1952 (m), 1777
(m) cm-1; 1H NMR (CD3COCD3) δ 7.56-7.00 (m, 8H, C6H4CF3
+ C6H4CH3), 6.27 (s, 2H, C5H4), 5.75 (s, 2H, C5H4), 5.30 (s,
2H, C5H4), 5.26 (s, 2H, C5H4), 2.24 (s, 3H, C6H4CH3), 0.65 (s,
3H, SiCH3), 0.47 (s, 3H, SiCH3); MS m/e 532 (M+), 504 (M+
-
CO), 476 (M+ - 2CO), 448 (M+ - 3CO), 485 (M+ - SCH3).
Anal. Calcd for C24H24O3SFe2Si: C, 53.23; H, 4.54. Found: C,
53.79; H, 5.09.
3H, SiCH3), 0.53 (s, 3H, SiCH3); MS m/e 662 (M+), 578 (M+
-
[F e2(µ-CO){µ-C(SC6H 5)C6H 4CH 3-p }(CO)2{(η5-C5H 4)2Si-
(CH3)2}] (13): red crystals (70% yield); mp 135-136 °C dec;
IR (CH2Cl2) ν(CO) 1982 (vs), 1951 (s), 1772 (s) cm-1; 1H NMR
(CD3COCD3) δ 7.36-6.54 (m, 9H, C6H5 + C6H4CH3), 6.23 (s,
2H, C5H4), 5.66 (s, 2H, C5H4), 5.26 (s, 2H, C5H4), 5.20 (s, 2H,
C5H4), 2.02 (s, 3H, C6H4CH3), 0.64 (s, 3H, SiCH3), 0.51 (s, 3H,
SiCH3); MS m/e 594 (M+), 538 (M+ - 2CO), 485 (M+ - SC6H5).
Anal. Calcd for C29H26O3SFe2Si: C, 58.60; H, 4.41. Found: C,
58.24; H, 4.55.
3CO), 539 (M+ - SC6H4CH3). Anal. Calcd for C30H25O3F3S-
Fe2Si: C, 54.40; H, 3.8. Found: C, 54.77; H, 4.02.
P r ep a r a t ion of [F e2(µ-CO)(µ-CC6H 4CF 3-p )(CO)2{(η5-
C5H4)2Si(CH3)2}(µ-S)(µ-SC6H5)F e2(CO)6] (18). To a solution
of 0.179 g (0.52 mmol) of [(µ-S)2Fe2(CO)6]17 in 30 mL of THF
at -78 °C was added dropwise 0.52 mmol of C6H5Li with
vigorous stirring within 10 min. The color of the solution
turned from red to emerald green. After 10 min stirring at
-78 °C, the resulting solution of [(µ-SLi)(µ-SC6H5)Fe2(CO)6]18
was cooled to -100 °C and then poured rapidly onto 0.370 g
(0.437 mmol) of freshly (in situ) prepared 6 in 50 mL of THF
previously cooled to -100 °C. The reaction proceeded rapidly
to form a dark solution. The mixture was stirred at -100 to
-50 °C for 5-6 h, during which time the dark solution turned
dark red. The resulting mixture was evaporated under high
vacuum at -50 to -40 °C to dryness. The dark residue was
chromatographed on an alumina column at -25 °C with
petroleum ether as the eluant. After removal of a small yellow
band from the column, the purple-red band was eluted with
petroleum ether/CH2Cl2 (10:1) and collected. The solvent was
removed in vacuo, and the residue was recrystallized from
[F e 2 (µ-C O ){µ-C (S C 6 H 4 M e -p )C 6 H 4 M e -p }(C O )2 {(η5 -
C5H4)2Si(CH3)2}] (14): purple-red crystals (64% yield); mp
108-110 °C dec; IR (CH2Cl2) ν(CO) 1982 (s), 1950 (m), 1771
1
(m) cm-1; H NMR (CD3COCD3) δ 7.33-6.55 (m, 8H, 2C6H4-
CH3), 6.20 (s, 2H, C5H4), 5.65 (s, 2H, C5H4), 5.25 (s, 2H, C5H4),
5.22 (s, 2H, C5H4), 2.24(s, 3H, SC6H4CH3), 2.03 (s, 3H,
C6H4CH3), 0.62 (s, 3H, SiCH3), 0.49 (s, 3H, SiCH3); MS m/e
608 (M+), 580 (M+ - CO), 524 (M+ - 3CO), 485 (M+
-
SC6H4CH3). Anal. Calcd for C30H28O3SFe2Si: C, 59.22; H, 4.64.
Found: C, 59.24; H, 4.77.
[F e2(µ-CO){µ-C(SCH 3)C6H 4CF 3-p }(CO)2{(η5-C5H 4)2Si-
(CH3)2}] (15): purple-red crystals (77% yield); mp 104-110

Iron-Sulfur Cluster Bridging Carbene Complexes
Organometallics, Vol. 20, No. 19, 2001 4095
Ta ble 2. Selected Bon d Len gth s (Å)a a n d An gles (d eg)a for Com p lexes 9, 13, a n d 16
9
13
16
9
13
16
Fe(1)-Fe(2)
2.515(3)
2.04(1)
2.00(1)
1.88(2)
1.96(2)
1.18(2)
1.75(2)
1.14(2)
1.75(2)
1.14(2)
52.2(4)
77.0(4)
50.8(4)
47.8(4)
81.9(7)
50.4(5)
96.7(6)
95.6(6)
143(1)
2.510(2)
2.032(10)
2.01(1)
1.90(1)
1.91(1)
1.18(1)
1.76(1)
1.15(1)
1.74(1)
1.14(1)
52.0(3)
76.9(4)
51.1(3)
48.7(4)
82.3(6)
49.0(4)
95.6(5)
96.1(5)
137.9(10)
139(1)
2.516(3)
2.08(2)
2.01(1)
1.87(2)
1.88(2)
1.21(2)
1.73(2)
1.18(2)
1.73(2)
1.18(2)
53.2(4)
76.0(5)
50.8(3)
47.7(5)
84.1(8)
48.1(5)
94.7(6)
96.5(7)
137(1)
C(1)-C(2)
C(1)-S
1.55(2)
1.81(1)
1.81(2)
1.88(1)
1.88(1)
1.83(2)
1.83(2)
2.134
1.52(1)
1.81(1)
1.78(1)
1.87(1)
1.90(1)
1.85(1)
1.85(1)
2.134
1.47(2)
1.80(1)
1.79(2)
1.87(1)
1.90(2)
1.85(2)
1.88(2)
2.122
Fe(1)-C(1)
Fe(2)-C(1)
S-C(26)
Fe(1)-C(10)
Si-C(17)
Fe(2)-C(10)
Si-C(18)
C(10)-O(2)
Si-C(23)
Fe(1)-C(8)
Si-C(24)
C(8)-O(1)
Fe(1)-C(Cp) (av)
Fe(2)-C(Cp) (av)
Fe(2)-C(9)
2.130
2.134
2.126
C(9)-O(3)
Fe(1)-Fe(2)-C(1)
Fe(1)-C(1)-Fe(2)
Fe(2)-Fe(1)-C(1)
Fe(1)-Fe(2)-C(10)
Fe(1)-C(10)-Fe(2)
Fe(2)-Fe(1)-C(10)
C(1)-Fe(1)-C(10)
C(1)-Fe(2)-C(10)
Fe(1)-C(10)-O(2)
Fe(2)-C(10)-O(2)
Fe(1)-C(1)-S
Fe(2)-C(1)-S
123.2(7)
118.0(9)
121.5(9)
173(1)
118.2(5)
119.2(7)
125.2(8)
172(1)
119.5(7)
116.2(9)
124.7(9)
172(1)
Fe(1)-C(1)-C(2)
Fe(2)-C(1)-C(2)
Fe(1)-C(8)-O(1)
Fe(2)-C(9)-O(3)
Fe(1)-C(17)-Si
Fe(2)-C(18)-Si
C(17)-Si-C(18)
C(10)-Fe(2)-C(1)
C(1)-S-C(26)
175(1)
172(1)
173(1)
119.5(6)
120.2(6)
106.8(6)
95.6(6)
120.3(5)
120.5(6)
104.9(4)
96.1(5)
121.0(7)
121.2(7)
104.1(7)
96.5(7)
134(1)
111.9(6)
138(1)
109.5(7)
104.2(7)
110.1(5)
107.3(8)
109.9(5)
a
Estimated standard deviations in the least significant figure are given in parentheses.
Ta ble 3. Selected Bon d Len gth s (Å)a a n d An gles (d eg)a for Com p lex 18
Fe(1)-Fe(2)
2.505(3)
2.053(11)
2.041(11)
1.895(15)
1.936(14)
1.183(14)
1.762(16)
1.150(15)
52.5(3)
75.4(4)
52.1(3)
48.5(4)
81.7(6)
Fe(2)-C(9)
1.761(14)
1.148(14)
1.510(15)
1.847(12)
1.780(11)
1.870(15)
1.859(14)
1.826(13)
137.7(13)
112.9(5)
112.6(6)
120.0(9)
122.8(8)
121.4(7)
122.7(7)
112.9(5)
112.6(6)
Si-C(24)
1.863(11)
2.297(4)
2.296(3)
2.236(4)
2.246(4)
2.531(3)
2.106
Fe(1)-C(1)
C(9)-O(3)
S(1)-Fe(3)
Fe(2)-C(1)
C(1)-C(2)
S(1)-Fe(4)
Fe(1)-C(10)
S(1)-C(1)
S(2)-Fe(3)
Fe(2)-C(10)
S(2)-C(26)
S(2)-Fe(4)
C(10)-O(2)
Si-C(17)
Fe(3)-Fe(4)
Fe(1)-C(8)
Si-C(18)
Fe(1)-C(Cp) (av)
Fe(2)-C(Cp) (av)
S(1)-C(1)-C(2)
C(1)-S(1)-Fe(3)
C(1)-S(1)-Fe(4)
S(1)-Fe(3)-Fe(4)
S(1)-Fe(4)-Fe(3)
Fe(3)-S(1)-Fe(4)
S(2)-Fe(3)-Fe(4)
S(2)-Fe(4)-Fe(3)
Fe(3)-S(2)-Fe(4)
C(8)-O(1)
Si-C(23)
2.092
Fe(1)-Fe(2)-C(1)
Fe(1)-C(1)-Fe(2)
Fe(2)-Fe(1)-C(1)
Fe(1)-Fe(2)-C(10)
Fe(1)-C(10)-Fe(2)
Fe(2)-Fe(1)-C(10)
C(1)-Fe(1)-C(10)
C(1)-Fe(2)-C(10)
Fe(1)-C(10)-O(2)
Fe(2)-C(10)-O(2)
Fe(1)-C(1)-S(1)
Fe(2)-C(1)-S(1)
Fe(1)-C(1)-C(2)
Fe(2)-C(1)-C(2)
Fe(1)-C(17)-Si
Fe(2)-C(18)-Si
Fe(1)-C(1)-S(1)
Fe(2)-C(1)-S(1)
109.6(7)
123.9(4)
124.5(4)
56.55(10)
56.56(10)
66.88(11)
55.82(11)
55.42(11)
68.77(12)
49.9(4)
97.6(5)
96.7(5)
140.6(13)
a
Estimated standard deviations in the least significant figure are given in parentheses.
petroleum ether/CH2Cl2 solution at -80 °C to give 0.28 g (68%,
based on 7) of blackish red crystals of 18: mp 96-98 °C dec;
dures for the reaction of 6 with [(µ-SLi)(µ-SC6H5)Fe2(CO)6],
compound 8 (0.52 g, 0.69 mmol) was treated with [(µ-SLi)(µ-
SC6H5)Fe2(CO)6], prepared (in situ) by the reaction of [(µ-
S)2Fe2(CO)6] (0.275 g, 0.80 mmol) with 0.80 mmol of C6H5Li,
at -100 to -40 °C for 5 h, during which time the green solution
turned dark red. Further treatment as that for the preparation
of 18 yielded 0.42 g (72%, based on 8) of 20 as blackish red
crystals: mp 58-59 °C dec; IR (CH2Cl2) ν(CO) 2062 (m), 2052
IR (CH2Cl2) ν(CO) 2059 (m), 2024 (s), 1991 (s), 1787 (m) cm-1
;
1H NMR (CD3COCD3) δ 7.75-7.15 (m, 9H, C6H5 + C6H4CF3),
5.62-5.31 (m, 8H, C5H4), 0.83 (s, 3H, SiCH3), 0.69 (s, 3H,
SiCH3); MS m/e 539 [M+ - (µ-S)(µ-SC6H5)Fe2(CO)6], 421 [(µ-S)-
(µ-SC6H5)Fe2(CO)6+], 337 (µ-S)(µ-SC6H5)Fe2(CO)3+], 84 (CH2-
Cl2+). Anal. Calcd for C35H23O9F3S2Fe4Si‚CH2Cl2: C, 41.37; H,
2.41. Found: C, 40.95; H, 2.51.
(s), 2015 (vs, br), 1974 (vs, br), 1810 (s) cm-1 1H NMR
;
P r ep a r a tion of [F e2(µ-CO)(µ-CC6H5)(CO)2(η5-C5H5)2(µ-
S)(µ-SC6H5)F e2(CO)6] (19). As used in the reaction of 6 with
[(µ-SLi)(µ-SC6H5)Fe2(CO)6], compound 7 (0.51 g, 0.68 mmol)
was treated with [(µ-SLi)(µ-SC6H5)Fe2(CO)6], prepared (in situ)
by the reaction of [(µ-S)2Fe2(CO)6] (0.275 g, 0.80 mmol) with
0.80 mmol of C6H5Li, at -100 to -40 °C for 5 h, during which
time the green solution turned dark red. Further treatment
as that for the preparation of 18 gave 0.39 g (68%, based on
7) of blackish red crystals of 19: mp 54-56 °C dec; IR (CH2Cl2)
(CD3COCD3) δ 7.60-7.25 (m, 10H, 2C6H5), 5.28 (m, 2H,
CH2Cl2), 5.14 (s, 5H, C5H5), 4.94 (s, 5H, C5H5), 2.51 (s, 3H,
C6H4CH3); MS m/e 254 [M+ - 3CO - C6H5 - (µ-S)(µ-SC6H5)-
Fe2(CO)6], 344 [(µ-S)2Fe2(CO)6+], 232 [(µ-S)2Fe2(CO)2+], 204 [(µ-
S)2Fe2(CO)+], 176 [(µ-S)2Fe2+], 84 (CH2Cl2+). Anal. Calcd for
C
33H22O9S2Fe4‚CH2Cl2: C, 43.68; H, 2.59. Found: C, 43.87; H,
2.81.
X-r a y Cr ysta l Str u ctu r e Deter m in a tion s of Com p lexes
9, 13, 16, a n d 18. The single crystals of 9, 13, 16, and 18
suitable for X-ray diffraction study were obtained by recrys-
tallization from petroleum ether/CH2Cl2 solution at -80 °C.
Single crystals were mounted on a glass fiber and sealed with
epoxy glue. The X-ray diffraction intensity data were collected
with Rigaku AFC7R and Brock Smart diffractometer at 20 °C
using Mo KR radiation (λ ) 0.71069 Å) with a ω-2θ scan mode.
The structures of 9, 13, and 18 were solved by direct
methods and expanded using Fourier techniques. For 9, some
non-hydrogen atoms were refined anisotropically, while the
rest were refined isotropically. For 13 and 18, the non-
ν(CO) 2062 (s), 2053 (s), 2025 (vs), 1977 (vs, br), 1811 (m) cm-1
;
1H NMR (CD3COCD3) δ 7.82-7.11 (m, 10H, 2C6H5), 5.26 (s,
5H, C5H5), 4.97 (s, 5H, C5H5); MS m/e 338 [M+ - C6H5 - (µ-S)-
(µ-SC6H5) Fe2(CO)6], 282 [M+ - 2CO - C6H5 - (µ-S)(µ-SC6H5)-
Fe2(CO)6], 344 [(µ-S)2Fe2(CO)6+], 288 [(µ-S)2Fe2(CO)4+], 260 [(µ-
S)2Fe2(CO)3+], 232 [(µ-S)2Fe2(CO)2+], 204 [(µ-S)2Fe2(CO)+], 176
[(µ-S)2Fe2+]. Anal. Calcd for C32H20O9S2Fe4: C, 45.97; H, 2.41.
Found: C, 46.13; H, 2.66.
P r ep a r a t ion of [F e2(µ-CO)(µ-CC6H 4CH 3-p )(CO)2(η5-
C5H 5)2(µ-S)(µ-SC6H 5)F e2(CO)6] (20). Similar to the proce-

4096 Organometallics, Vol. 20, No. 19, 2001
Wang et al.
F igu r e 1. Molecular structure of 9, showing the atom-
numbering scheme. Thermal ellipsoids are shown at 45%
probability. CH2Cl2 has been omitted for clarity.
F igu r e 2. Molecular structure of 13, showing the atom-
numbering scheme with 40% thermal ellipsoids.
(CO)2(η5-C5H5)2]BBr4 (7, Ar ) C6H5; 8, Ar ) p-CH3C6H4),9
with an excess of BBr3 at -65 °C to produce diiron
cationic bridging carbyne complexes [Fe2(µ-CO)(µ-CAr)-
(CO)2{(η5-C5H4)2Si(CH3)2}]BBr4 (4, Ar ) C6H5; 5, Ar )
p-CH3C6H4; 6, Ar ) p-CF3C6H4) as brown-red solids in
84-87% yields (eq 1).
hydrogen atoms were refined anisotropically. For the three
complexes the hydrogen atoms were included but not refined.
The final cycle of full-matrix least-squares refinement gave
agreement factors of R ) 0.058 and Rw ) 0.056 for 9, R ) 0.058
and Rw ) 0.050 for 13, and R ) 0.0590 and Rw ) 0.0707 for
18. The structure of 16 was solved by heavy-atom Patterson
methods and expanded using Fourier techniques. The non-
hydrogen atoms were refined anisotropically. The hydrogen
atoms were included but not refined. The final cycle of full-
matrix least-squares refinement gave agreement factors of R
) 0.071 and Rw ) 0.079.
The details of the crystallographic data and the procedures
used for data collection and reduction information for 9, 13,
16, and 18 are given in Table 1. Selected bond lengths and
angles are listed in Tables 2 and 3. The atomic coordinates
and Biso/Beq, anisotropic displacement parameters, complete
bond lengths and angles, least-squares planes for 9, 13, 16,
and 18, and the molecular structure of 16) are given in the
Supporting Information. The molecular structures of 9, 13, and
18 are given in Figures 1, 2, and 3, respectively.
Resu lts a n d Discu ssion
The dimethylsilane-bridged bis(η5-cyclopentadienyl)-
diiron bridging alkoxy carbene complexes [Fe2(µ-CO)-
(µ-CAr)(CO)2{(η5-C5H4)2Si(CH3)2}]BBr4 (1, Ar ) C6H5;
2, Ar ) p-CH3C6H4; 3, Ar ) p-CF3C6H4)15 in ether were
treated, similar to the procedures for the preparation
of the cationic carbyne complexes [Fe2(µ-CO)(µ-CAr)-

Iron-Sulfur Cluster Bridging Carbene Complexes
Organometallics, Vol. 20, No. 19, 2001 4097
Cationic bridging carbyne complexes 4-6 are only
sparingly soluble in polar organic solvents, such as THF
and CH2Cl2. They are very sensitive to air, moisture,
and temperature and can be stored at low temperature
(below -65 °C) only for a short period. The compositions
and structures of complexes 4-6 were established on
the basis of their IR and 1H NMR spectra. Since
complexes 4-6 contain diethyl ether and are extremely
labile, we cannot get satisfactory results of the elemen-
tal analyses.
The freshly prepared (in situ) cationic carbyne com-
plex [Fe2(µ-CO)(µ-CC6H5)(CO)2(η5-C5H5)2]BBr4 (4) reacts
with about 15-20% molar excess of NaSR (R ) CH3,
C6H5, p-CH3C6H4), in THF at low temperature (-80 to
-20 °C) for 4-5 h. After workup as described in the
Experimental Section, the brown-red diiron bridging
mercaptocarbene complexes [Fe2(µ-CO){µ-C(SR)C6H5}-
(CO)2{(η5-C5H4)2Si(CH3)2}] (9, R ) CH3; 10, R ) C6H5;
11, R ) p-CH3C6H4) were isolated in 70-75% yields (eq
2).
The analogous reactions of [Fe2(µ-CO)(µ-CAr)(CO)2-
(η5-C5H5)2]BBr4 (5, Ar ) p-CH3C6H4; 6, Ar ) p-CF3C6H4)
with NaSR under the same conditions yielded the
corresponding bridging mercaptocarbene complexes
[Fe2(µ-CO){µ-C(SR)Ar}(CO)2{(η5-C5H4)2Si(CH3)2}] (12,
Ar ) p-CH3C6H4, R ) CH3; 13, Ar ) p-CH3C6H4, R )
C6H5; 14, Ar ) p-CH3C6H4, R ) p-CH3C6H4; 15, Ar )
p-CF3C6H4, R ) CH3; 16, Ar ) p-CF3C6H4, R ) C6H5;
17, Ar ) p-CF3C6H4, R ) p-CH3C6H4) (eq 2) in 64-78%
yields.
F igu r e 3. Molecular structure of 18, showing the atom-
numbering scheme with 40% thermal ellipsoids. CH2Cl2
has been omitted for clarity.
signals attributed to the dicyclopentadienyl protons
showed four resonances at about 6.30-5.05 ppm, similar
to those of precursor complexes 1-3.15
The structures of complexes 9, 13, and 16, which have
been established by X-ray diffraction studies, resemble
that of 1, except that the substituent on the µ-carbene
carbon is a SR group in 9, 13, and 16 and an OEt group
in 1. The mercapto and aryl groups are attached to the
µ-carbene carbon, and the two cyclopentadienyl rings
are in totally eclipsed configuration, as anticipated from
1
the IR and H NMR spectra.
The distances of the Fe-Fe bond bridged by the
µ-carbene ligand in 9, 13, and 16 are 2.515(3), 2.510(2),
and 2.516(3) Å, respectively, which are the same as that
found in 1 (2.513(1) Å).15 The µ-carbene carbon almost
symmetrically bridges the Fe-Fe bond with a C(1)-
Fe(1) of 2.03-2.08 Å and a C(1)-Fe(2) of 2.00-2.01 Å
for 9, 13, and 16. The µ-C-Fe distances are much longer
than the µ-Fe-CO bond (C(10)-Fe(1) 1.87-1.90 Å,
C(10)-Fe(2) 1.88-1.96 Å) but approximately equal to
that in [Fe2(µ-CO){µ-C(CN)NHPh}CC(CO)2(η5-C5H5)]
(C(4)-Fe(1) 2.004(2) Å, C(4)-Fe(2) 2.028(2) Å).19 The
C(1)-S distances (1.81(1) Å for 9 and 13, 1.80(1) Å for
16) indicate that they are essentially single bonds by
comparison with standard C(sp2)-S (1.76 Å)20 single
bond and C(sp3)-S(1.81 Å)20 single bond distances.
Complexes 9-17 are readily soluble in polar organic
solvents but slightly soluble in nonpolar solvents. They
are sensitive to air and temperature in solution but
relatively stable in the solid state. The formulas shown
in eq 2 for complexes 9-17 were established by elemen-
Like NaSR, (µ-phenylthio)(µ-thiolato)hexacarbonyl-
diiron, [(µ-SLi)(µ-SC6H5)Fe2(CO)6], can also react with
cationic carbyne complex 6 under similar conditions to
produce the iron-sulfur cluster bridging carbene
1
tal analysis and IR, H NMR, and mass spectroscopy
(Experimental Section). The IR spectra of 9-17 showed
two CO absorption bands at 1984-1949 cm-1 and one
at 1779-1771 cm-1 in the bridging ν(CO) region,
evidence for an Fe2(µ-CO)(CO)2 moiety in these com-
plexes. In the 1H NMR spectra of 9-17, the proton
(19) Albano, V. G.; Bordoni, S.; Braga, D.; Busetto, L.; Palazzi, A.;
Zanotti, V. Angew. Chem., Int. Ed. Engl. 1991, 30, 847.
(20) (a) Rozsondai, B.; Schultz, G.; Hargittai, I. J . Mol. Struct. 1981,
70, 309. (b) Samdal, S.; Seip, H. M.; Torgrimsen, T. J . Mol. Struct.
1979, 57, 105.

4098 Organometallics, Vol. 20, No. 19, 2001
Wang et al.
complex [Fe2(µ-CO)(µ-CC6H4CF3-p)(CO)2{(η5-C5H4)2Si-
(CH3)2}(µ-S)(µ-SC6H5)Fe2(CO)6] (18) in 68% yield (eq 3).
owing to its strong electron-withdrawing action, which
promotes the nucleophilic attack of the [(µ-S)(µ-SC6H5)-
Fe2(CO)6]- anion on the µ-carbyne carbon of 6, resulting
in the formation of iron-sulfur cluster bridging carbene
complex 18.
The formulas shown in eqs 3 and 4 for complexes 18-
20 were based on the elemental analysis and IR, 1H
NMR, and mass spectroscopy (Experimental Section) as
well as X-ray crystallography. The IR spectra of 18-20
in the ν(CO) region showed an absorption band at ca.
1810 cm-1 attributed to the bridging CO ligand, in
addition to four terminal CO absorption bands at 2062-
1974 cm-1, which signified Fe2(µ-CO)(CO)2 and Fe2(CO)6
moieties in these complexes.
The molecular structure (Figure 3) of 18 was estab-
lished by X-ray diffraction studies, which show that it
is a derivative of (µ-S)2Fe2(CO)6 in which the bridging
carbene carbon is bonded by a (µ-S)(µ-SC6H5)Fe2(CO)6
moiety. The average Fe-µ-C distance of 2.047 Å is
slightly longer than that found (2.020-2.022 Å) in
mercaptocarbene complexes 9 and 13. The µ-C-S(1)
bond length of 1.847(12) Å in 25 is significantly longer
than that in the analogous iron-sulfur cluster carbene
complex [{η5-C5H5(CO)2RedCC6H5}(µ-S)(µ-SC6H5)Fe2-
(CO)6] (1.70(2) Å)12 and slightly longer than that in
complexes 9 and 13 (1.80(1)-1.81(1) Å). Except for the
[Fe2(µ-CO)(µ-CC6H4CF3-p)(CO)2{(η5-C5H4)2Si(CH3)2}] unit,
the structure of the (µ-S)(µ-SC6H5)Fe2(CO)6 portion of
18 is nearly the same as that in analogous complexes
[{η5-C5H5(CO)2RedCC6H5}(µ-S)(µ-SC6H5)Fe2(CO)6],12
[(C6H5S)Fe2(CO)6S-S(CO)6Fe2(SC6H5)],21 and [(µ-CH3S)-
Fe2(CO)6]2[µ-S-(m-CH2C6H4CH2)-S-µ],22 as illustrated by
the following parameters (the value for 18 is followed
by the same parameters for Re carbene complexes,
[(C6H5S)Fe2(CO)6S-S(CO)6Fe2(SC6H5)], and [(µ-CH3S)-
Fe2(CO)6]2[µ-S-(m-CH2C6H4CH2)-S-µ]: Fe-Fe (2.531(3),
2.523(4), 2.523 (av), 2.510 (av) Å), average Fe-S (2.269,
2.260, 2.261, 2.260 Å), average Fe-S-Fe (67.825, 67.45,
68.25, 67.46°). The distance of the S atom to the phenyl
(S(2)-C(26) 1.780(11) Å) in 18 is somewhat shorter than
that in [{η5-C5H5(CO)2RedCC6H5}(µ-S)(µ-SC6H5)Fe2-
(CO)6] (S(2)-C(13) 1.82(2) Å)12 but is the same within
experimental error as that in [(C6H5S)Fe2(CO)6S-
S(CO)6Fe2(SC6H5)] (average 1.786 Å).21
Analogous iron-sulfur cluster bridging carbene com-
plexes [Fe2(µ-CO)(µ-CC6H5)(CO)2(η5-C5H5)2(µ-S)(µ-SC6H5)-
Fe2(CO)6] (19) and [Fe2(µ-CO)(µ-CCH3C6H4-p)(CO)2(η5-
C5H5)2(µ-S)(µ-SC6H5)Fe2(CO)6] (20) in 68% and 72%,
respectively, were also obtained by the reactions of
diiron cationic bridging carbyne complexes [Fe2-
(µ-CO)(µ-CAr)(CO)2(η5-C5H5)2]BBr4 (7, Ar ) C6H5; 8,
p-CH3C6H4) with [(µ-SLi)(µ-SC6H5)Fe2(CO)6] (eq 4).
The structural features of the [Fe2(µ-CO)(µ-CC6H4-
CF3-p)(CO)2{(η5-C5H4)2Si(CH3)2}] unit of 18 are very
similar to those of the same unit in complex 1, as
illustrated by the following parameters (the value for
18 is followed by the same parameters for 1): Fe(1)-
Fe(2) (2.505, 2.513(1) Å), average Fe-C(Cp) (2.099,
2.123 Å), average µ-C-Fe (2.047, 2.045 Å), average Fe-
C(10) (1.916, 1.906 Å), Fe(1)-C(1)-Fe(1) (75.4(4)°,
76.9(2)°), Fe(1)-C(10)-Fe(2) (81.7(6)°, 82.5(2)°).
The title reaction shows a variety of reactions of the
dimethylsilane-bridged bis(η5-cyclopentadienyl)diiron
cationic bridging carbyne complexes with nucleophiles
to give a series of diiron bridging carbene complexes.
This offers a new, convenient, and useful method for
the preparation and structural modification of dimetal
However, not all such diiron cationic bridging carbyne
complexes can react with [(µ-S)(µ-SC6H5)Fe2(CO)6]-
anion to produce the iron-sulfur cluster bridging car-
bene complexes since the cationic bridging carbyne
complexes, 4 and 5, where the aryl substituents at the
µ-carbyne carbon are a phenyl and a p-tolyl group,
respectively, react with [(µ-SLi)(µ-SC6H5)Fe2(CO)6] un-
der the same conditions to give not analogous iron-
sulfur cluster bridging carbene complex but rather a
decomposition mixture which cannot be isolated by
column chromatography or by recrystallization. This
suggests that the different cyclopentadienyl ligands and
aryl substituents at the bridging carbyne carbon exert
a great influence on the reactivity of the diiron cationic
bridging carbyne complexes. In the case of complex 6,
the electron-withdrawing p-CF3C6H4 group increased
electrophilic reactivity of the bridging carbyne carbon
(21) Seyferth, D.; Kinwan, A. M. J . Organomet. Chem. 1985, 281,
111.
(22) Song, Li.-C.; Kadiata, M.; Wang, J .-T. J . Organomet. Chem.
1990, 391, 387.

Iron-Sulfur Cluster Bridging Carbene Complexes
Organometallics, Vol. 20, No. 19, 2001 4099
Su p p or tin g In for m a tion Ava ila ble: Tables of positional
parameters and Biso/Beq, H atom coordinates, anisotropic
displacement parameters, complete bond lengths and angles,
and least-squares planes for 9, 13, 16, and 18. This material
is available free of charge via the Internet at http://pubs.acs.org.
bridging carbene complexes. In particular, it offers a
new route to the iron-sulfur cluster bridging carbene
complexes.
Ack n ow led gm en t. Financial support from the Na-
tional Natural Science Foundation of China and the
Science Foundation of the Chinese Academy of Sciences
is gratefully acknowledged.
OM010322R