The reaction of [{Co(η5-C5 H5)}2{Fe(CO)2(PPh3)} (μ3-S)(μ3-CS)] and related complexes with carbon disulfide (see abstract)

Article abstract of DOI:10.1039/b308320a

[{Co(η⁵-C₅H₅)}₂{Fe(CO) (L)₂}(μ₃-S)(μ₃-CS)] complexes 1 where (L)₂ = (a) (CO)(PPh₃), (b) (CO) {P(OPh)₃}, (c) (CO)(PBu₃ⁿ), (d) (CNMe)₂ and (e) (CNMes)₂ (Mes = 2,4,6-Me₃C₆H₂), but not (CO)(CNMes), react with CS₂ under reflux to give [{Co(η⁵-C₅ H₅)}₂{Fe(L)₂}(μ₃-S) (μ₃-C₂S₃)], 2, in which a CS₂ molecule has been incorporated into a FeSC(S*)SC heterocycle with a trithiocarbonate moiety bridging the Fe-C cluster edge. Clusters 2 react with incoming ligands either by simple ligand substitution, or by displacement of CS₂ to form clusters of type 1. The exocyclic sulfur atom S* is nucleophilic and with electrophiles E forms [{Co(η⁵-C₅H₅)}₂ {Fe(L)₂}(μ₃-S)(μ₃-C₂ S₃E] adducts which contain S*→E bonds where E = Me⁺ [3]⁺, Et⁺ [4]⁺, HgCl₂ [5], and I₄ (or I⁺) [6]. The clusters 2a-c and the [3]⁺ and [4]⁺ derived from them are chiral as indicated by their NMR spectra, and do not racemize on the NMR timescale. The structures of 2a·2C₆H₆ and [3a]I·C₆H₆·CHCl₃ are reported. Cluster 2a contains a very short Fe-C_μ bond as compared with 1a, and it is suggested that in many respects the FeSC(S)SC_μ ring is best regarded as a metallo-1,3-dithiole-2-thione (or metallovinyl trithiocarbonate) with a Fe-C_μ double bond which, on alkylation at the exocyclic S*, adopts a more delocalised electronic structure with a longer Fe-C_μ bond. Spectroscopic and electrochemical data for the new compounds are discussed.

Full text of DOI:10.1039/b308320a

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The reaction of [{Co(ꢀ5-C5H5)}2{Fe(CO)2(PPh3)}(ꢁ3-S)(ꢁ3-CS)]
and related complexes with carbon disulfide. Synthesis, structure
and reactivity of [{Co(ꢀ5-C5H5)}2{Fe(CO)(L)}(ꢁ3-S)(ꢁ3-C2S3)]
derivatives (L ؍ PR3 and CNR)
Anthony R. Manning,*a C. John McAdam,b Anthony J. Palmer,a Brian H. Robinsonb and
Jim Simpsonb
a Department of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland.
E-mail: Anthony.Manning@ucd.ie
b Department of Chemistry, University of Otago, PO Box 56, Dunedin, New Zealand.
E-mail: Brobinson@alkali.otago.ac.nz; Jsimpson@alkali.otago.ac.nz
Received 21st July 2003, Accepted 18th September 2003
First published as an Advance Article on the web 29th September 2003
[{Co(η5-C5H5)}2{Fe(CO)(L)2}(µ3-S)(µ3-CS)] complexes 1 where (L)2 = (a) (CO)(PPh3), (b) (CO){P(OPh)3},
(c) (CO)(PBun ), (d) (CNMe)2 and (e) (CNMes)2 (Mes = 2,4,6-Me3C6H2), but not (CO)(CNMes), react with CS2
3
under reflux to give [{Co(η5-C5H5)}2{Fe(L)2}(µ3-S)(µ3-C2S3)], 2, in which a CS2 molecule has been incorporated
into a FeSC(S*)SC heterocycle with a trithiocarbonate moiety bridging the Fe–C cluster edge. Clusters 2 react with
incoming ligands either by simple ligand substitution, or by displacement of CS2 to form clusters of type 1. The
exocyclic sulfur atom S* is nucleophilic and with electrophiles E forms [{Co(η5-C5H5)}2{Fe(L)2}(µ3-S)(µ3-C2S3E]
adducts which contain S* E bonds where E = Meϩ [3]ϩ, Etϩ [4]ϩ, HgCl2 [5], and I4 (or Iϩ) [6]. The clusters 2a–c and
the [3]ϩ and [4]ϩ derived from them are chiral as indicated by their NMR spectra, and do not racemize on the NMR
timescale. The structures of 2aؒ2C6H6 and [3a]IؒC6H6ؒCHCl3 are reported. Cluster 2a contains a very short Fe–Cµ
bond as compared with 1a, and it is suggested that in many respects the FeSC(S)SCµ ring is best regarded as a
metallo-1,3-dithiole-2-thione (or metallovinyl trithiocarbonate) with a Fe–Cµ double bond which, on alkylation at
the exocyclic S*, adopts a more delocalised electronic structure with a longer Fe–Cµ bond. Spectroscopic and
electrochemical data for the new compounds are discussed.
recorded on an AD Instruments Powerlab 4SP computer-
Introduction
controlled potentiostat. Scan rates of 0.05–1 V sϪ1 were typi-
Cleavage of the η2-CS2 ligand in [Fe(PPh3)2(CO)2(η2-CS2)] by
cally employed for cyclic voltammetry and for Osteryoung
square-wave voltammetry, square-wave step heights of 1–5 mV,
a square amplitude of 15–25 mV with a frequency of 30–240
Hz. All potentials are referenced to decamethylferrocene which
[Co(η5-C5H5)(PPh3)2] gives [{Co(η5-C5H5)}2{Fe(CO)2(PPh3)}-
(µ3-S)(µ3-CS)], 1a, from which can be prepared many [{Co(η5-
C5H5)}2{Fe(CO)3Ϫn(L)n}(µ3-S)(µ3-CS)] complexes, 1 (L = PR3 or
CNR; n = 1 or 2).1,2 As would be expected, the S atom of
was chosen as the reference because it shows no variation in
the µ3-CS ligand in 1 is a powerful nucleophile and forms [{Co-
reference potential with solvent; to convert to an approximate
(η5-C5H5)}2{Fe(CO)3-n(L)n}(µ3-S)(µ3-CS E)] adducts with
SCE value in dichloromethane add 0.53 V; E1/2 for sublimed
electrophiles E.1,2 More surprisingly, with CS2 it forms similar
ferrocene was 0.55 V.
adducts which also contain a Fe–S bond. Part of this work has
ESR spectra were measured on a Bruker EMX X-band
been reported previously.3 Since then there has been a report of
spectrometer. The compound was dissolved in a 1 : 1 mixture of
the complex Ru3(CO)4(µ-PCy2)2(µ-Ph2CH2PPh2)(µ3-S)(µ3-C2S3)
CH2Cl2–C2H4Cl2 with 0.1 M [Bu4N]PF6. The solution was
reduced electrochemically in an in situ electrolysis cell in the
which also contains the C2S3 ligand.4
cavity of the EPR spectrometer at room temperature.
Experimental
Reaction of [{Co(ꢀ5-C5H5)}2{Fe(CO)2(L)}(ꢁ3-S)(ꢁ3-CS)] and
Literature methods were used to prepare [{Co(η5-C5H5)}2-
[{Co(ꢀ5-C5H5)}2{Fe(CO)(L)2}(ꢁ3-S)(ꢁ3-CS)], 1, with CS2
{Fe(CO)2(L)}(µ3-S)(µ3-CS)] (L = PPh3, P(OPh)3, PBun and
3
CNC6H2Me3-2,4,6) and [{Co(η5-C5H5)}2{Fe(CO)(CNR)2}-
(µ3-S)(µ3-CS)] (R = Me and 2,4,6-Me3C6H2).1,2 Other chemicals
were purchased.
A solution of [{Co(η5-C5H5)}2{Fe(CO)2(PPh3)}(µ3-S)(µ3-CS)],
1a (0.5 g, 0.72 mmol), in carbon disulfide (8 cm3) was refluxed
for 12 h. The solution was allowed to cool and stand for
12 h. A brown precipitate was separated by filtration, and the
filtrate chromatographed on alumina. Dichloromethane–
hexane–tetrahydrofuran mixtures eluted unreacted 1a (80 mg)
and then a brown band. From this was isolated a brown solid
which was combined with the brown precipitate (above) and the
whole recrystallized from benzene–carbon disulfide mixtures
to give brown crystals of [{Co(η5-C5H5)}2{Fe(CO)(PPh3)}-
(µ3-S)(µ3-C2S3)]ؒ½C6H6, 2aؒ½C6H6. Yield 0.27 g, 57% (Found:
C, 52.9; H, 3.6. C31H25Co2FeOPS4ؒ½C6H6 requires C, 53.1; H,
3.7%). IR (cmϪ1 in CH2Cl2 with relative peak heights in paren-
theses) νCO 1925 (10); νCS 1020 (5.5), 1009 (3.0). (cmϪ1 in KBr
with relative peak heights in parentheses) νCO 1917 (10); νCS
1020 (4.0), 1005 (2.5, sh). 1H NMR (δ in CDCl3) 7.40 (m, 18H,
Unless stated otherwise, all reactions were carried out at
room temperature under an atmosphere of nitrogen in dried
and deoxygenated solvents. Where necessary, reactions were
monitored by IR spectroscopy.
IR spectra were run on a Perkin Elmer Paragon 2000 FT IR
spectrometer. NMR spectra were run on a JEOL JNM-GX-270
MHz spectrometer. Elemental analyses were carried out in the
Microanalytical Laboratory of University College Dublin.
Cyclic and square wave voltammetry in CH2Cl2 were per-
formed for all compounds using a three-electrode cell with a
polished disk, Pt (2.27 mm2) as the working electrode; solutions
were ∼10Ϫ3 M in electroactive material and 0.10 M in support-
ing electrolyte (triply recrystallised [Bu4N]PF6). Data was
D a l t o n T r a n s . , 2 0 0 3 , 4 4 7 2 – 4 4 8 1
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
4472

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PPh3 and C6H6), 4.91 (s, 5H, C5H5), 4.12 (s, 5H, C5H5). 13C
NMR (δ in CDCl3) 346.1 (d, JPC = 15.3 Hz, Cµ–S), 243.4
(d, JPC = 18.7 Hz, S–C–S), 218.7 (d, JPC = 22.2 Hz, CO),
135.1 (d, JPC = 42.6 Hz, ipso-C6H5), 133.6 (d, JPC = 10.2 Hz,
o-C6H5), 130.2 (s, p-C6H5), 128.3 (d, JPC = 10.3 Hz, m-C6H5),
86.1 (s, C5H5), 84.9 (s, C5H5). 31P NMR (δ in CDCl3) 60.36
(s, PPh3).
o-C6H2Me3), 128.9 (s, m-C6H2Me3), 126.8 (s, p-C6H2Me3), 85.31
(s, C5H5), 21.6 (s, p-C6H2(CH3)3), 19.3 (s, o-C6H2(CH3)3).
A solution of [{Co(η5-C5H5)}2{Fe(CO)2(CNMes)}(µ3-S)-
(µ3-CS)], 1f (0.01 g, 0.17 mmol) in carbon disulfide (9 cm3) and
benzene (12 cm3) was refluxed for 10 h. The products were sep-
arated by chromatography as above to give [{Co(η5-C5H5)}2-
{Fe(CNMes)2}(µ3-S)(µ3-C2S3)] 2e (0.017 g, 45% based on
CNMes) Some [{Co(η5-C5H5)}2{Fe(CO)(CNMes)2}(µ3-S)-
(µ3-CS)] was also formed and identified by comparison with an
authentic sample.2
A similar procedure starting from [{Co(η5-C5H5)}2{Fe(CO)2-
(P(OPh)3)}(µ3-S)(µ3-CS)], 1b (0.5 g, 70 mmol) with a reflux time
of 15 h gave recovered 1b (80 mg) and, after a final recrystalliz-
ation from dichloromethane–hexane, brown crystals of [{Co-
(η5-C5H5)}2{Fe(CO)(P(OPh)3)}(µ3-S)(µ3-C2S3)]ؒ½CH2Cl2, 2bؒ
½CH2Cl2. Yield 0.345 g, 60% (Found: C, 46.0; H, 3.1. C31H25-
Co2FeO4PS4ؒ½CH2Cl2 requires C, 45.9; H, 3.1%). IR (cmϪ1 in
CH2Cl2 with relative peak heights in parentheses) νCO 1950 (10);
νCS 1024 (7.6), 1007 (3.2). (cmϪ1 in KBr with relative peak
heights in parentheses) νCO 1941 (10); νCS 1023 (5.0), 1010
Reaction of [{Co(ꢀ5-C5H5)}2{Fe(CO)2(PPh3)}(ꢁ3-S)(ꢁ3-C2S3)],
2a, with CNMes
A solution of 2a (0.053 g, 0.07 mmol) and CNMes (0.25 cm3) in
dichloromethane (20 cm3) and benzene (15 cm3) was refluxed
for 2 min after which time 2a was consumed. Two products were
separated by chromatography and purified by crystallization.
They were shown to be [{Co(η5-C5H5)}2{Fe(CO)(CNMes)2}-
(µ3-S)(µ3-CS)], 1e (yield 0.032, 60%, from toluene–diethyl ether)
and [{Co(η-C5H5)}2{Fe(CNMes)2}(µ3-S)(µ3-C2S3)], 2e (yield
0.018 g, 25%, from tetrahydrofuran–diethyl ether).
1
(3.8). H NMR (δ in CDCl3) 7.20 (m, 15H, P(OPh)3), 4.68 (s,
5H, C5H5), 4.30 (s, 5H, C5H5). 13C NMR (δ in CDCl3) 349.3 (d,
JPC = 28.0 Hz, Cµ–S), 244.0 (d, JPC = 23.6 Hz, S–C–S), 214.5 (d,
JPC = 30.1 Hz, CO), 151.2 (d, JPC = 8.6 Hz, ipso-C6H5), 129.7 (s,
o-C6H5), 125.2 (s, p-C6H5), 121.4 (d, JPC = 4.3 Hz, m-C6H5), 85.9
(s, C5H5), 85.3 (s, C5H5).
Reactions of [{Co(ꢀ5-C5H5)}2{Fe(CO)(PR3)}(ꢁ3-S)(ꢁ3-C2S3)], 2,
with alkylating agents
The reaction of [{Co(η5-C5H5)}2{Fe(CO)2(PBun )}(µ3-S)-
3
(µ3-CS)], 1c (0.50 g, 0.78 mmol) with CS2 was carried out in
refluxing carbon disulfide (6 cm3) and pentane (6 cm3). After
75 h the mixture was evaporated to dryness and the residue
chromatographed as above to give recovered 1c (194 mg) and a
brown solid which was crystallized from toluene–hexane mix-
A solution of [{Co(η5-C5H5)}2{Fe(CO)(PR3)}(µ3-S)(µ3-C2S3)],
2, (ca. 0.1 g) (R = (a) Ph, (b) OPh and (c) Bun) in dichloro-
methane (3 cm3) was filtered and benzene (25 cm3) and R1I
(1 cm3, R1 = Me or Et) added to it. The mixture was stirred for
16 h. The brown precipitates were then filtered off, washed with
benzene and diethyl ether, and recrystallized from dichloro-
methane–diethyl ether mixtures to give brown crystals of the
salts [{Co(η5-C5H5)}2{Fe(CO)(PR3)}(µ3-S)(µ3-C2S3R1)]I, [3]I
(R1 = Me) and [4]I (R1 = Et) in yields of 70–80%. Under the
same conditions MeOSO2CF3 gave [{Co(η5-C5H5)}2{Fe(CO)-
(PR3)}(µ3-S)(µ3-C2S3Me)][SO3CF3] salts. The salts where PR3 =
PBun3 were oils which could not be purified further, whilst those
derived from 2d and 2e were formed but were unstable and
could not be purified.
tures. It was identified as [{Co(η5-C5H5)}2{Fe(CO)(PBun )}-
3
(µ3-S)(µ3-C2S3)]ؒC6H5CH3ؒH2O,
2cؒC6H5CH3ؒH2O.
Yield
0.278 g, 80% (Found: C, 46.0; H, 3.1. C25H37Co2FeOPS4ؒ
C6H5CH3ؒH2O requires C, 45.9; H, 3.1%). IR (cmϪ1 in CH2Cl2
with relative peak heights in parentheses) νCO 1927 (10); νCS
1020 (5.0), 1009 (3.5). (cmϪ1 in KBr with relative peak heights in
parentheses) νCO 1919 (10); νCS 1014 (2.9), 1000 (2.9). 1H NMR
(δ in CDCl3) 4.82 (s, 5H, C5H5), 4.59 (s, 5H, C5H5), 1.80 (m, 6H,
PBun ), 1.30 (m, 12H, PBun ), 0.91 (t, 9H, JHH = 6.9 Hz, PBun ).
3
3
3
13C NMR (δ in CDCl3) 348.4 (d, JPC = 13.6 Hz, Cµ–S), 244.3 (d,
JPC = 18.8 Hz, S–C–S), 218.2 (d, JPC = 22.2 Hz, CO), 86.0 (s,
[{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3Me)]I, [3a]I.
Yield 0.091 g, 80% (Found: C, 42.5; H, 3.4. C32H28Co2FeIOPS4
requires C, 43.3; H, 3.2). IR (cmϪ1 in CH2Cl2) νCO 1947. (cmϪ1 in
KBr) νCO 1925. 1H NMR (δ in CDCl3) 7.40 (m, 15H, PPh3), 5.22
(s, 5H, C5H5), 4.48 (s, 5H, C5H5), 3.08 (s, 3H, CH3). 13C NMR
(δ in CDCl3) 348.5 (d, JPC = 15.3 Hz, Cµ–S), 221.6 (d, JPC = 20.5
Hz, S–C–S), 214.5 (d, JPC = 20.5 Hz, CO), 133.6 (d, JPC = 44.3
Hz, ipso-C6H5), 133.3 (d, JPC = 10.2 Hz, o-C6H5), 130.9 (s,
p-C6H5), 128.7 (d, JPC = 10.2 Hz, m-C6H5), 87.5 (s, C5H5), 86.1
(s, C5H5), 22.1 (s, CH3). 31P NMR (δ in CDCl3) 51.8 (s, PPh3).
[{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3Me)][SO3-
CF3], [3a][SO3CF3]. Yield 0.086 g, 75% (Found: C, 41.4; H, 2.9;
P, 3.5. C33H28Co2F3FeO4PS5 requires C, 41.3; H, 2.9; P, 3.4%).
C5H5), 84.5 (s, C5H5), 29.5 (d, JPC = 23.9 Hz, PBun ), 25.8 (s,
3
PBun ), 24.4 (d, JPC = 13.7 Hz, PBun ), 13.8 (s, PBun ).
3
3
3
A
solution of [{Co(η5-C5H5)}2{Fe(CO)(CNMe)2}(µ3-S)-
(µ3-CS)], 1d (0.1 g, 0.20 mmol) in carbon disulfide (6 cm3) and
benzene (12 cm3) was refluxed for 2 h. The solvent was removed
from the reaction mixture at reduced pressure and the resi-
due chromatographed as above to give a product which was
crystallized from tetrahydrofuran–diethyl ether mixtures to
give brown crystals of [{Co(η5-C5H5)}2{Fe(CNMe)2}(µ3-S)-
(µ3-C2S3)], 2d. Yield 0.071 g, 65% (Found: C, 46.0; H, 3.0; N,
5.1. C16H16N2Co2FeS4 requires C, 45.9; H, 3.1; N, 5.2%). IR
(cmϪ1 in CH2Cl2 with relative peak heights in parentheses) νCN
2174 (10), 2151 (7.0); νCS 1019 (2.9, sh), 1012 (4.2). (cmϪ1 in KBr
with relative peak heights in parentheses) νCN 2163 (10), 2140
1
IR (cmϪ1 in CH2Cl2) νCO 1948. (cmϪ1 in KBr) νCO 1933. H
NMR (δ in CDCl3) 7.40 (m, 15H, PPh3), 5.12 (s, 5H, C5H5),
4.38 (s, 5H, C5H5), 3.04 (s, 3H, CH3). 13C NMR (δ in CDCl3)
348.6 (d, JPC = 15.3 Hz, Cµ–S), 221.3 (d, JPC = 20.5 Hz, S–C–S),
214.6 (d, JPC = 20.5 Hz, CO), 134.1 (d, JPC = 44.3 Hz,
ipso-C6H5), 133.5 (d, JPC = 10.2 Hz, o-C6H5), 131.0 (s, p-C6H5),
128.8 (d, JPC = 10.2 Hz, m-C6H5), 87.5 (s, C5H5), 86.1 (s, C5H5),
21.9 (s, 3H, CH3). 31P NMR (δ in CDCl3) 51.8 (s, PPh3).
1
(8.1); νCS 1013 (3.8), 999 (4.0). H NMR (δ in CDCl3) 4.62 (s,
10H, C5H5), 3.25 (s, 6H, CNCH3). 13C NMR (δ in CDCl3) 344.9
(s, Cµ–S), 244.4 (s, S–C–S), 158.4 (s, CNMe), 84.95 (s, C5H5),
31.2 (s, CNCH3).
Under the same conditions, [{Co(η5-C5H5)}2{Fe(CO)-
(CNMes)2}(µ3-S)(µ3-CS)] 1e (0.08 g, 0.11 mmol) (CNMes =
CNC6H2Me3-2,4,6),gives[{Co(η5-C5H5)}2{Fe(CNMes)2}(µ3-S)-
(µ3-C2S3)], 2e. Yield 0.051 g, 60% (Found: C; 51.1; H, 4.3; N,
3.9. C32H32N2Co2FeS4 requires C, 51.5; H, 4.3; N 3.8%). IR
(cmϪ1 in CH2Cl2 with relative peak heights in parentheses) νCN
2117 (10), 2084 (7.0); νCS 1018 (6, sh), 1012 (6.6). (cmϪ1 in KBr
with relative peak heights in parentheses) νCN 2101 (8.0), 2069
(8.1); νCS 1017 (3.8), 1004 (2.4, sh). 1H NMR (δ in CDCl3) 6.80
(s, 4H, m-C6H2) 4.67 (s, 10H, C5H5), 2.25 (s, 12H, o-CH3), 2.24
(s, 6H, p-CH3). 13C NMR (δ in CDCl3) 350.2 (s, Cµ–S), 244.8 (s,
S–C–S), 171.4 (s, CNMes), 138.4 (s, ipso-C6H2Me3), 134.3 (s,
[{Co(η5-C5H5)}2{Fe(CO)(P(OPh)3)}(µ3-S)(µ3-C2S3Me)]ICؒ H2-
Cl2, [3b]IؒCH2Cl2. Yield 0.11 g, 80% (Found: C, 39.1; H, 2.9; I,
12.4. C32H28Co2FeIO4PS4ؒCH2Cl2 requires C, 38.8; H, 2.9; I
13.3%). IR (cmϪ1 in CH2Cl2) νCO 1969. (cmϪ1 in KBr) νCO 1956.
1H NMR (δ in CDCl3) 7.27 (m, 15H, P(OPh)3), 5.05 (s, 5H,
C5H5), 4.73 (s, 5H, C5H5), 3.18 (s, 3H, CH3). 13C NMR (δ in
CDCl3) 353.3 (d, JPC = 25.6 Hz, Cµ–S), 222.6 (d, JPC = 22.1 Hz,
S–C–S), 210.4 (d, JPC = 27.3 Hz, CO), 150.8 (d, JPC = 10.2 Hz,
ipso-C6H5), 130.1 (s, o-C6H5), 125.9 (s, p-C6H5), 121.0 (d, JPC
=
5.1 Hz, m-C6H5), 87.5 (s, C5H5), 86.7 (s, C5H5), 22.1 (s, 3H, CH3).
D a l t o n T r a n s . , 2 0 0 3 , 4 4 7 2 – 4 4 8 1
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Table 1 Crystal data and structure refinement for [{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3)]ؒ2C6H6, 2aؒ2C6H6, and [{Co(η5-C5H5)}2-
{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3Me)]IؒCHCl3ؒC6H6, [3a]IؒCHCl3ؒC6H6
2aؒ2C6H6
[3a]IؒCHCl3ؒC6H6
Empirical formula
Formula weight
T/K
C43H37Co2FeOPS4
902.65
293(2)
0.71073
C39H35Cl3Co2FeIOPS4
1085.84
300(2)
λ/Å
0.71073
Crystal system
Space group
a/Å
b/Å
c/Å
Monoclinic
P21/n
9.853(13)
19.97(2)
20.61(2)
91.79(4)
4055(8)
4
Monoclinic
P21/n
12.9130(7)
20.9619(10)
16.2086(8)
100.2930(10)
4316.8(4)
4
β/Њ
V/Å3
Z
Dc/g cmϪ3
1.478
1.440
1.671
2.253
µ/mmϪ1
F(000)
Crystal size/mm
θ Range/Њ
1848
0.95 × 0.65 × 0.07
2.04–25.01
6687
6380 (0.12960)
Empirical
2160
0.45 × 0.15 × 0.10
1.60–23.39
12780
4746 (0.0314)
Empirical
1.000, 0.721
Reflections collected
Independent reflections (Rint
Absorption correction
Max., min. transmission
Refinement method
Data/restraints/parameters
Goodness-of-fit on F 2
Final R indices [I > 2σ(I )]
R indices (all data)
)
0.925, 0.419
Full-matrix least squares on F 2
6380/6/469
4746/36/470
1.078
R1 = 0.0488, wR2 = 0.1283
R1 = 0.0576, wR2 = 0.1328
0.616, Ϫ0.627
0.832
R1 = 0.0692, wR2 = 0.1575
R1 = 0.1488, wR2 = 0.1823
1.482, Ϫ0.620
Largest diff. peak, hole/e ÅϪ3
[{Co(η5-C5H5)}2{Fe(CO)(P(OPh)3)}(µ3-S)(µ3-C2S3Me)][SO3-
CF3], [3b][SO3CF3]. Yield 0.082 g, 70% (Found: C, 41.3; H, 2.9.
C33H28Co2F3FeO7PS5 requires C, 41.4; H, 2.9%). IR (cmϪ1 in
was crystallized from dichloromethane–diethyl ether to give
brown [{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3HgCl2)]ؒ
H2O, 5aؒH2O. Yield 0.121 g, 90% (Found: C, 36.0; H, 2.5; Cl,
6.9. C31H25Cl2Co2FeHgIOPS4ؒH2O: C, 35.8; H, 2.6; Cl, 6.9%).
1
CH2Cl2) νCO 1969. (cmϪ1 in KBr) νCO 1956. H NMR (δ in
1
CDCl3) 7.25 (m, 15H, P(OPh)3), 4.96 (s, 5H, C5H5), 4.64 (s, 5H,
C5H5), 3.17 (s, 3H, CH3). 13C NMR (δ in CDCl3) 353.3 (d,
JPC = 27.3 Hz, Cµ–S), 222.7 (d, JPC = 22.1 Hz, S–C–S), 210.4 (d,
JPC = 29.0 Hz, CO), 150.8 (d, JPC = 10.2 Hz, ipso-C6H5), 130.1 (s,
o-C6H5), 125.9 (s, p-C6H5), 121.0 (d, JPC = 5.1 Hz, m-C6H5), 87.4
(s, C5H5), 86.5 (s, C5H5), 21.8 (s, 3H, CH3).
IR (cmϪ1 in CH2Cl2) νCO 1941. (cmϪ1 in KBr) νCO 1930. H
NMR (δ in CDCl3) 7.45 (m, 15H, PPh3), 5.03 (s, 5H, C5H5),
4.28 (s, 5H, C5H5).
Reactions of [{Co(ꢀ5-C5H5)}2{Fe(CO)(PPh3)}(ꢁ3-S)(ꢁ3-C2S3)],
2a, with I2
[{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3Et)]IؒCH2Cl2,
[4a]IؒCH2Cl2,. Yield 0.098 g, 80% (Found: C, 41.8; H, 3.2; I,
12.9. C33H30Co2FeIOPS4.CH2Cl2 requires C, 41.4; H, 3.3; I,
12.9%). IR (cmϪ1 in CH2Cl2) νCO 1947. (cmϪ1 in KBr) νCO 1933
A solution of I2 (0.145 g) in dichloromethane (10 cm3) was
titrated into one of [{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)-
(µ3-C2S3)], 2a, (0.05 g, 0.067 mmol) in dichloromethane
(50 cm3). The reaction was monitored by IR spectroscopy
which showed no further changes after the addition of ca. 2.2
molar equivalents of I2. The reaction mixture was filtered and
the solvent removed at reduced pressure. The residue was
recrystallized from tetrahydrofuran–diethyl ether mixtures
to give [{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3I)]I3, 6a.
Yield 0.064, 75% (Found: C, 30.2; H, 2.2; P, 2.4; I, 38.8.
C31H25Co2FeHgI4OPS4 requires C, 29.7; H, 2.0; P, 2.5; I,
40.5%). IR (cmϪ1 in CH2Cl2) νCO 1942. (cmϪ1 in KBr) νCO 1921.
1
(10), 1918 (9.0). H NMR (δ in CDCl3) 7.35 (m, 15H, PPh3),
5.22 (s, 5H, C5H5), 4.47 (s, 5H, C5H5), 3.62 (br s, 2H, CH2), 1.54
(t, 3H, JHH = 8.3 Hz, CH3). 13C NMR (δ in CDCl3) 348.2 (d,
JPC = 15.3 Hz, Cµ–S), 220.3 (d, JPC = 20.5 Hz, S–C–S), 214.6 (d,
JPC = 22.2 Hz, CO), 133.6 (d, JPC = 44.3 Hz, ipso-C6H5), 133.4
(d, JPC = 10.2 Hz, o-C6H5), 131,0 (s, p-C6H5), 128.7 (d, JPC
=
10.2 Hz, m-C6H5), 87.6 (s, C5H5), 86.2 (s, C5H5), 33.9 (s,
CH2),13.3 (s, CH3).
[{Co(η5-C5H5)}2{Fe(CO)(P(OPh)3)}(µ3-S)(µ3-C2S3Et)]Iؒ
2CH2Cl2, [4b]Iؒ2CH2Cl2. Yield 0.099 g, 74% (Found: C, 38.0; H,
3.0. C33H30Co2FeIO4PS4.CH2Cl2 requires C, 37.5; H, 3.0%). IR
The structures of [{Co(ꢀ5-C5H5)}2{Fe(CO)(PPh3)}(ꢁ3-S)-
(ꢁ3-C2S3)], 2a, and [{Co(ꢀ5-C5H5)}2{Fe(CO)(PPh3)}(ꢁ3-S)-
(ꢁ3-C2S3Me)]I, [3a]I
1
(cmϪ1 in CH2Cl2) νCO 1968. (cmϪ1 in KBr) νCO 1947. H NMR
(δ in CDCl3) 7.25 (m, 15H, P(OPh)3), 5.07 (s, 5H, C5H5), 4.73 (s,
5H, C5H5), 3.75 (q, 2H, JHH = 7.6 Hz, CH2), 1.66 (t, 3H, JHH
=
Crystals of 2aؒ2C6H6 and [3a]IؒC6H6ؒCHCl3 were grown from
CHCl3–benzene. Data were collected from the weakly diffract-
ing crystals of 2a at 293(2) K on a Siemens diffractometer using
graphite monochromated Mo-Kα radiation and the ω-scan
technique. Lorentz polarisation and absorption corrections
were applied using SHELXTL.5 For [3a]I, collection at 300(2)
K used a Bruker SMART CCD diffractometer, data was pro-
cessed using SMART,6 and empirical absorption corrections
applied using SADABS.7 Crystal data are summarized for both
molecules in Table 1.
7.5 Hz, CH2). 13C NMR (δ in CDCl3) 353.3 (d, JPC = 25.5 Hz,
Cµ–S), 222.0 (d, JPC = 22.1 Hz, S–C–S), 210.5 (d, JPC = 29.0 Hz,
CO), 150.8 (d, JPC = 8.5 Hz, ipso-C6H5), 130.0 (s, o-C6H5), 125.8
(s, p-C6H5), 121.0 (d, JPC = 5.1 Hz, m-C6H5), 87.6 (s, C5H5), 86.7
(s, C5H5), 33.9 (s, CH2), 22.1 (s, 3H, CH3).
Reactions of [{Co(ꢀ5-C5H5)}2{Fe(CO)(PPh3)}(ꢁ3-S)(ꢁ3-C2S3)],
2a, with HgCl2
HgCl2 (0.04 g, 0.15 mmol) was added to a solution of [{Co(η5-
C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3)], 2a, (0.1 g, 0.13 mmol)
in dichloromethane (20 cm3). After 6 min, the mixture was fil-
tered and the solvent removed at reduced pressure. The residue
Both structures were solved by direct methods using
SHELXS-868 for 2a and SHELXS-979 for [3a]I, and were
refined by full-matrix least-squares using SHELXL-97.10
D a l t o n T r a n s . , 2 0 0 3 , 4 4 7 2 – 4 4 8 1
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Table 2 Selected bond lengths (Å) and bond angles (Њ)
2a
3a
1a
Cluster bond lengths
Fe(1)–Co(1)
Fe(1)–Co(2)
Co(1)–Co(2)
Fe(1)–C(1)
Co(1)–C(1)
Co(2)–C(1)
Fe(1)–S(1)
Co(1)–S(1)
Co(2)–S(1)
Fe(1)–P(1)
Fe(1)–C(3)O
C(3)–O(3)
2.624(3)
2.502(3)
2.461(4)
1.881(11)
1.881(10)
1.880(10)
2.208(4)
2.168(3)
2.186(3)
2.302(4)
1.758(11)
1.173(11)
1.774(10)
Fe(1)–Co(2)
Fe(1)–Co(1)
Co(1)–Co(2)
Fe(1)–C(1)
Co(2)–C(1)
Co(1)–C(1)
Fe(1)–S(1)
Co(2)–S(1)
Co(1)–S(1)
Fe(1)–P(1)
Fe(1)–C(4)O
C(4)–O(4)
2.5965(14)
2.5054(16)
2.4340(13)
1.894(6)
1.869(7)
1.871(8)
2.186(3)
2.125(2)
2.148(2)
2.279(2)
1.744(7)
1.143(2)
1.749(7)
Fe(1)–Co(1)
Fe(1)–Co(2)
Co(1)–Co(2)
Fe(1)–C(1)
Co(1)–C(1)
Co(2)–C(1)
Fe(1)–S(1)
Co(1)–S(1)
Co(2)–S(1)
Fe(1)–P(1)
Fe(1)–C(2)O
C(2)–O(2)
2.5099(6)
2.5061(6)
2.4378(5)
2.805(2)
1.910(3)
1.922(3)
2.1925(7)
2.1266(7)
2.1370(7)
2.353(7)
1.764(3)
1.147(3)
1.638(2)
C(1)–S(2)
C(1)–S(2)
C(1)–S(2)
Cluster bond angles
Co(1)–Fe(1)–Co(2)
Fe(1)–Co(1)–Co(2)
Fe(1)–Co(2)–Co(1)
Fe(1)–C(1)–Co(1)
Fe(1)–C(1)–Co(2)
Co(1)–C(1)–Co(2)
Fe(1)–S(1)–Co(1)
Fe(1)–S(1)–Co(2)
Co(1)–S(1)–Co(2)
P(1)–Fe(1)–C(3)O
P(1)–Fe(1)–S(4)
57.31(8)
58.86(9)
63.83(6)
88.4(4)
83.4(4)
81.7(4)
73.68(11)
69.43(10)
68.83(12)
95.6(3)
88.05(11)
94.1(3)
Co(1)–Fe(1)–Co(2)
Fe(1)–Co(2)–Co(1)
Fe(1)–Co(1)–Co(2)
Fe(1)–C(1)–Co(2)
Fe(1)–C(1)–Co(1)
Co(1)–C(1)–Co(2)
Fe(1)–S(1)–Co(2)
Fe(1)–S(1)–Co(1)
Co(1)–S(1)–Co(2)
P(1)–Fe(1)–C(4)O
P(1)–Fe(1)–S(4)
56.95(4)
59.64(4)
63.41(4)
87.3(3)
83.4(3)
81.2(3)
74.06(8)
70.62(7)
69.45(7)
95.1(2)
88.64(8)
93.0(3)
Co(1)–Fe(1)–Co(2)
Fe(1)–Co(1)–Co(2)
Fe(1)–Co(2)–Co(1)
Fe(1)–C(1)–Co(1)
Fe(1)–C(1)–Co(2)
Co(1)–C(1)–Co(2)
Fe(1)–S(1)–Co(1)
Fe(1)–S(1)–Co(2)
Co(1)–S(1)–Co(2)
P(1)–Fe(1)–C(2)O
P(1)–Fe(1)–C(3)O
C(2)–Fe(1)–C(3)
58.15(2)
60.84(2)
61.001(14)
77.72(9)
77.31(9)
79.01(10)
71.04(2)
70.73(3)
69.75(2)
95.93(9)
94.12(9)
97.75(14)
S(4)–Fe(1)–C(3)O
S(4)–Fe(1)–C(4)O
Heterocycle bond lengths
Fe(1)–C(1)
Fe(1)–S(4)
C(1)–S(2)
C(2)–S(2)
C(2)–S(3)
C(2)–S(4)
Fe(1)–S(4)
1.881(10)
2.301(4)
1.774(10)
1.731(11)
1.680(11)
1.768(11)
2.301(4)
Fe(1)–C(1)
Fe(1)–S(4)
C(1)–S(2)
C(2)–S(2)
C(2)–S(3)
C(2)–S(4)
Fe(1)–S(4)
C(3)–S(3)
1.894(6)
2.239(3)
1.749(7)
1.700(9)
1.715(8)
1.684(7)
2.239(3)
1.798(9)
Heterocycle bond angles
Fe(1)–C(1)–S(2)
C(1)–S(2)–C(2)
S(2)–C(2)–S(4)
S(2)–C(2)–S(3)
S(3)–C(2)–S(4)
C(2)–S(4)–Fe(1)
S(4)–Fe(1)–C(1)
129.1(6)
99.7(5)
123.0(7)
121.1(7)
123.0(7)
108.1(4)
83.9(3)
Fe(1)–C(1)–S(2)
C(1)–S(2)–C(2)
S(2)–C(2)–S(4)
S(2)–C(2)–S(3)
S(3)–C(2)–S(4)
C(2)–S(4)–Fe(1)
S(4)–Fe(1)–C(1)
C(2)–S(3)–C(3)
127.9(5)
97.5(3)
120.3(4)
122.6(4)
117.1(5)
107.1(3)
84.7(2)
104.0(4)
Hydrogen atoms were included as fixed contributions to Fc with
fixed isotropic temperature factors. All non-hydrogen atoms
were refined anisotropically.
CCDC reference numbers 207316 and 215760.
See http://www.rsc.org/suppdata/dt/b3/b308320a/ for crystal-
lographic data in CIF or other electronic format.
Difference Fourier synthesis following the location of all
atoms revealed additional large peaks in both structures. For 2a
the peaks could be sensibly assigned to the carbon atoms of
three benzene solvate molecules, two of which lie about inver-
sion centres, while for [3a]I they revealed the presence of both
chloroform and benzene solvate molecules. In both cases, inclu-
sion of the solvates, together with H atoms in calculated posi-
tions, in the refinements led to significant improvements in the
residuals. The relatively high values of R1 and wR2 for 2a can
largely be attributed to weakly diffracting crystals; only 2930 of
the 6380 reflection were ‘observed’.
Results and discussion
When the µ3-CS clusters [{Co(η5-C5H5)}2{Fe(CO)(L)2}(µ3-S)-
(µ3-CS)], 1, are refluxed in carbon disulfide solution, a molecule
of CS2 is taken up and CO is lost to give the [{Co(η5-C5H5)}2-
{Fe(L)2}(µ3-S)(µ3-C2S3)], 2, clusters where L2 = (a) (CO)(PPh3),
(b) (CO){P(OPh)3}, (c) (CO)(PBun ), (d) (CNMe)2 and (e)
3
(CNMes)2 (Mes = 2,4,6-Me3C6H2), but not where L2 = (CO)-
(CNMes). 2 react with electrophiles E which attack the C2S3
ligand to give [{Co(η5-C5H5)}2{Fe(L)2}(µ3-S)(µ3-C2S3E)], where
E = Meϩ (3), Etϩ (4), HgCl2 (5) and Iϩ [6]ϩ. These reactions are
summarized in Scheme 1. The structures shown in the Scheme for
the various complexes are consistent with spectroscopic data and
have been confirmed for 2a and [3a]ϩ by X-ray crystallography.
The molecular structure and atom labelling of 2a is given in
Fig. 1, and that of the cation of [3a]I in Fig. 2. Selected bond
lengths and bond angles are summarised in Table 2 together
with those of 1a for comparison.
D a l t o n T r a n s . , 2 0 0 3 , 4 4 7 2 – 4 4 8 1
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Scheme 1
Fig. 1 The molecular structure and atom labelling of [{Co(η5-C5H5)}2-
{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3)]ؒ2C6H6, 2aؒ2C6H6. Displacement
ellipsoids are drawn at the 50% probability level. For clarity, only 2 C
atoms of the consecutively numbered cyclopentadienyl and phenyl
rings are labelled.
Fig. 2 The molecular structure and atom labelling of the cation
of [{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3Me)]IؒCHCl3ؒC6H6,
[3a]IؒCHCl3ؒC6H6. Displacement ellipsoids are drawn at the 50%
probability level. For clarity, only 2 C atoms of the consecutively
numbered cyclopentadienyl and phenyl rings are labelled.
Fixation of CS2 by 1
This is illustrated by the ease with which 1 are alkylated to give
[{Co(η5-C5H5)}2{Fe(CO)(L)2}(µ3-S)(µ3-CSR)]X salts.1 How-
ever, the µ-CS ligand of [{Co(η5-C5H5)}3(µ3-S)(µ3-CS)] is alkyl-
ated with equal facility,12,13 but [{Co(η5-C5H5)}3(µ3-S)(µ3-CS)]
does not react with CS2 to give [{Co(η5-C5H5)}3(µ3-S)(µ3-C2S3)].
This implies that the formation of such adducts is reversible
and that the C2S3 ligand in 2 is stabilized because the Fe
atoms in the postulated [{Co(η5-C5H5)}2{Fe(CO)(L)2}(µ3-S)-
(µ3-CSCS2)] intermediates are able to lose a two-electron ligand
and form an Fe–S bond. Surprisingly, CO is the ligand which is
replaced by S, whereas if 1a is reacted with either phosphines,
phosphites or isocyanides, triphenylphosphine is substituted
preferentially.2 If this ligation of S is so important in the stabil-
ization of 2, displacement of the ligating S atom from the co-
ordination shell of Fe by an incoming ligand L should reverse
the formation of the µ3-C2S3 to give 1 with the liberation of CS2.
Although CS2 is fixed as the C2S3 ligand by clusters 1a–e, it is
not a completely general reaction. [{Co(η5-C5H5)}2{Fe(CO)2-
(CNMes)}(µ3-S)(µ3-CS)], 1f, (CNMes = CNC6H2Me3-2,4,6)
reacts with CS2, but it does not give [{Co(η5-C5H5)}2{Fe(CO)-
(CNMes)}(µ3-S)(µ3-C2S3)], 2f. Instead the only isolable prod-
ucts are [{Co(η5-C5H5)}2{Fe(CO)(CNMes)2}(µ3-S)(µ3-CS)], 1e,
and [{Co(η5-C5H5)}2{Fe(CNMes)2}(µ3-S)(µ3-C2S3)], 2e. This
implies that either 2f is formed but is unstable or that 1f is
unstable under the reaction conditions used and on thermolysis
it gives 1e which is the true precursor of 2e.
The overall reaction of 1 ϩ CS2
2 is related to that of
thiolate anions RSϪ with CS2 which is used to prepare organo-
trithiocarbonate ions [RSCS2]Ϫ and in which the CS2 molecule
acts as an electrophile.11 In the present instance, it takes place
because the S atom of the µ3-CS ligand is very nucleophilic.
D a l t o n T r a n s . , 2 0 0 3 , 4 4 7 2 – 4 4 8 1
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However, such a reaction would compete with the substitution
of other ligands at the Fe atoms of 2. Both of these alternatives
have been observed in the reaction of 2a with CNMes (Mes =
C6H2Me3-2,4,6). 2e arises from replacement of PPh3 and CO by
CNMes, but with retention of the C2S3 ligand, and 1e arises
from replacement of PPh3 and CS2. The second pathway gives
the higher reaction yield.
NMR spectra
The 1H and 13C NMR spectra of 2–[4]X are consistent with the
proposed formulae. Resonances due to solvents of crystalliz-
ation and the organo groups R of phosphine and isocyanide
ligands are all present at the expected chemical shifts with the
correct integrations and showing the anticipated coupling con-
stants. However, much more important are the resonances due
to H and C atoms of the η5-C H , S C᎐S and S CSRϩ groups
᎐
5
5
2
2
Reactions of 2 with electrophiles
and the ligating C atoms of CO, CNR and µ3-C groups.
The Fe atom in 2a–c, [3a–c]X and [4a–c]X is chiral. Con-
sequently their two Co(η-C5H5) moieties are in different
environments so that two η-C5H5 resonances are observed in
2a–c react with electrophiles, E, to give adducts (Scheme 1).
These are brown solids soluble in polar organic solvents. They
are stable in the solid state but decompose slowly in solution.
Similar derivatives are formed by the isocyanide complexes 2d
and 2e, but they could not be characterized. The structure of
one of the adducts, [3a]I, has been determined by X-ray crystal-
lography which has confirmed that the nucleophilic site is the
exocyclic S* atom of the FeSC(S*)SCµ ring. All adducts have
similar spectra. Consequently it is reasonable to suggest that
they have structures similar to [3a]I, and that [3]X, (E = Meϩ),
1
both H and 13C NMR spectra. These observations imply that
there is no inversion of configuration of the Fe atoms on the
NMR time scale. Both enantiomers are observed in the crystal
structures of both 2a and [3a]I (see below). On the other hand,
in the NMR spectra of 2d and 2e single resonances are
observed for η-C5H5 and CNR ligands. It is probable that the
structures of these compounds is similar to that of 2a but with
Fe(CO)(PPh3) replaced by Fe(CNR)2. The two CNR ligands
are in different environments and consequently the two Co-
(η-C5H5) groups are not equivalent, but they can be made so by
a fast oscillation of the Fe(CNR)2S moiety (Fig. 3) even though
free rotation of the FeL3 group is prevented by the FeSCSC
ring.
Ϫ
[4]X (E = Etϩ), 5a (E = HgCl2) and 6a (E = IϩI3 or I4) have
S
C, S Hg or S I bonds. 5a and 6a are poorly soluble in
organic solvents, which suggests that they have polymeric struc-
tures with extensive Hg–Cl–Hg or I–I–I interactions. 6a has
been formulated as a salt containing a CS Iϩ ligand with an
I3Ϫ counterion because it requires two molar equivalents of I2 to
consume one of 2a, but even in these circumstances a network
of I–I interactions would be expected in the solid state.
The clusters [{Co(η5-C5H5)}2{Fe(CO)2(PPh3)}(µ3-S)(µ3-CS)]
and [{Co(η5-C5H5)}3(µ3-S)(µ3-CS)] form [{Co(η5-C5H5)}2-
{Fe(CO)2(PPh3)}(µ3-S)(µ3-CSE)] and [{Co(η5-C5H5)}3(µ3-S)-
(µ3-CSE)] adducts with a similar range of electrophiles with the
S atom of their µ3-CS ligand acting as the nucleophilic center.
However it is probably more relevant that in the trithio-
carbonate complexes [Co(η5C5H5)(PR3)(η2-S2CS)] the exocyclic
C᎐S also act as nucleophiles to mercury halides and iodine as
᎐
well as Rϩ.14
Fig. 3 Equivalencing of the η-C5H5 and CNR ligands X = S or SRϩ.
L1 = L2 = CNMe or CNMes of 2 and [3]ϩ.
IR spectra
As a consequence of 13C–31P coupling the µ3-C, S–C–S and
CO resonances of 2a–c, [3]X and [4]X are doublets, whilst the
µ3-C, S–C–S and CNR resonances of 2d and 2e are singlets.
Those due to the µ3-C atom are readily identified. Their chem-
ical shifts for 2 lie in the range δ 344.9–349.3 and depend to a
limited extent on the ligands coordinated to Fe. They are less
deshielded than those of the µ3-CS ligand of 1, e.g. δ 346.1 for
2a vs. δ 355.5 for 1a, whereas the µ3-C atoms of the corre-
sponding [{Co(η5-C5H5)}2{Fe(CO)2L}(µ3-S)(µ3-CSMe)]ϩ salts
are more deshielded (δ 366.6 when L = PPh3). Furthermore,
alkylation of the C2S3 ligand deshields this µ3-C atom to only a
limited extent with chemical shifts of δ 348.2–353.3 in the [3]ϩ
and [4]ϩ salts. In contrast, the chemical shift of the C atom of
the SC(S*)S moiety of 2 is almost independent of the ligand L
(δ 243.4–244.8) but becomes markedly less deshielded on
alkylation of S* in [3]ϩ and [4]ϩ (δ 220.3–222.0). For com-
parison, the 13C resonance of free CS2 is found at δ 192.6,16 it
shifts downfield to δ 205.1 in [Pt(PPh3)2{SC(S)N(Me)C(O)-
N(Ph)}] with its six-membered metallocyclic ring,16 and to
δ 279.5 when η2-bonded in [Fe{PPh(OEt)2}2(CO)2(η2-CS2)].17
The observed chemical shifts and the way in which they vary
indicate fundamental changes in the bonding in both CS2 and
the cluster 1 when they combine to form the CµSC(S*)SFe
heterocycle in 2, and when this is alkylated at the exocyclic
S* to give the CµSC(S*Rϩ)SFe heterocycle in [3]ϩ and [4]ϩ.
The IR spectra of 2–6 show many absorption bands, but the
only ones of interest which could be identified with any con-
fidence are those due to the ν(CO) and ν(CN) vibrations of the
coordinated carbonyl and isocyanide ligands, those due to
[SO3CF3]Ϫ ions of the salts, and, for 2, some bands at ca. 1000
cmϪ1 which we attribute to the ν(CS) vibrations of the C2S3
ligand
The ν(CO) and ν(CN) frequencies of [2], [3]ϩ and [4]ϩ are a
predictable function of the ligand set about Fe. The increase
in their frequencies in going from 2 to [3]X, [4]X, [5] or [6]
is to be anticipated as the presence of a electrophile bonded
to S makes the exocyclic CS group a better π-acceptor. This
is consistent with electronic communication between the C2S3
or C2S3Rϩ ligands and the cluster part of the molecules as
strongly indicated by molecular structures of 2a and [3a]I (see
below).
There are absorption bands in the IR spectra of 1 having
frequencies between ca. 1020 and 1050 cmϪ1 which are attri-
buted to the ν(CS) vibration of the µ3-CS ligand.2 On conver-
sion of 1 to 2 these are replaced by other bands in the
same region of the spectrum which are assumed to be due to
vibrations of the C2S3 moiety. There are usually two of them
and they have frequencies between ca. 1020 and 950 cmϪ1. On
alkylation of the exocyclic S atoms of 2 these bands disappear
and we were not able to identify their counterparts in the
spectra of [3]ϩ or [4]ϩ. The frequencies of these bands may be
compared with those of ca. 1035 and 860 cmϪ1 found for the
The structure of [{Co(ꢀ5-C5H5)}2{Fe(CO)(PPh3)}(ꢁ3-S)-
(ꢁ3-C2S3)], 2a
The structure of [{Co(η5-C5H5)}2{Fe(CO)2(PPh3)}(µ3-S)-
(µ3-CS)], 1a, is based on a FeCo2 isosceles triangle capped on
one face by a µ3-S ligand and on the other by a µ3-C atom of a
ν(C᎐S) and ν(C–S) in the spectra of the trithiocarbonate
᎐
complexes [Co(η5C5H5)(PR3)(η2-S2CS)],14 and 1067 cmϪ1 for
the thione (MeS)2C2S2CS.15 There will probably be much mix-
ing between the various vibrations of the C2S3 ligand.
D a l t o n T r a n s . , 2 0 0 3 , 4 4 7 2 – 4 4 8 1
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Table 3 Electrochemical dataa
b
1a
[1aMe]I
2a
[3a]I
Co3
[Co3Me]Ib
Epc (A)
Ϫ1.10
Ϫ1.00
–
Ϫ0.98
–
Ϫ0.54
Ϫ0.44
0.42
irrev.
0.69
0.59
Ϫ0.95
Ϫ0.83
–
Ϫ1.25
irrev.
Ϫ0.58c
irrev.
–
Ϫ1.06
irrev.
–
–
–
Epa (B)
Epc (C)
Epa (D)
Epa (E)
Epc (F)
Epa (G)
Epc (H)
Ϫ0.52
Ϫ0.43
0.9
Ϫ0.2
0.96e
irrev.
–
–
–
0.50
0.02
0.62
0.54
0.66
0.02
1.30
1.19
0.45
Ϫ0.05
1.30
irrev.
–
1.12d
1.05d
a In CH2Cl2; volts, 200 mV sϪ1, Pt, 0.1 M TBAPF6, from cyclic voltammetry; referenced against decamethylferrocene (SCE 0.53 V). Electron transfers
assigned as in text and Figs. 5 and 6. irrev. = irreversible. b Co3 = [{Co(η5-C5H5)}3(µ3-S)(µ3-CS)] and [Co3Me]I = [{Co(η5-C5H5)}3(µ3-S)(µ3-CSMe)]I.
c In acetone, –0.54 V. d In acetone, 1.03 and 0.96 V. e Multi-electron step at 1.33 V.
CS ligand. The two Fe–Co distances are comparable, 2.5061(6)
and 2.5099(6) Å, and the molecule possesses a near plane of
symmetry which includes Sµ, Fe and CSµ and bisects the
Co–Co bond.1
found in [{Co(η5-C5H5)}2{Fe(CO)2(PPh3)}(µ3-S)(µ3-CSMe)]ϩ 1
(cf. also with KS2CSMe above).
Bonding in the FeSC(S)SC heterocyclic ring of 2a and [3a]؉
Cluster 2a has a similar structure (Fig. 1, Table 2) but the
µ3-CS ligand is incorporated into a S–C(S)–S moiety which
bridges the µ3-C atom and Fe(1) to give a near planar C(1)–
S(2)–C(2){S(3)}–S(4)–Fe(1) heterocyclic ring with an exocyclic
One of the most puzzling aspects of the structures of 1a, 2a and
[3a]ϩ is the variation of the Fe(1)–C(1) bond length, 2.085(3),
1.881(11) and 1.895(8) Å, respectively. The distance in 1a is
similar to the Fe–C σ bond length in (η-C5H5)(OC)2Fe–CH2C-
(O)Mn(CO)5, 2.082(4) Å,20 which suggests that the Fe(1)–C(1)
bond order is close to unity. The distance in 2a is comparable to
C(1)᎐S(3). The coordination shell about each Co atom is com-
᎐
pleted by a η5-C5H5 group and about Fe by terminal CO
and PPh3 ligands. As there are three different ligands co-
ordinated to Fe, the molecule is chiral and both enantiomers are
found in the unit cell. The three ligands to Fe1 have interligand
bond angles of ca. 90Њ, and are arranged so that the CO ligand
lies close to the FeCo2 plane with a Co(1)–Fe(1)–C(3) angle of
144.6Њ.
that in (η-C H )(I)(OC)Fe᎐C(Ph)OMe, 1.849(10) Å,21 which
᎐
5
5
suggests that in this compound, Fe(1)–C(1) is largely a double
bond. If that is so, FeSC(S)SC may be formulated as a metallo-
analogue of a 1,3-dithiole-2-thione and its structure described
as a resonance hybrid of A and B (Fig. 4, X = S) where B is the
conflation of a number of charge separated mesomers in which
the positive charge is distributed over the atoms of the FeCSCS
heterocyclic ring and, as a consequence, the various C–S bonds
have bond orders between one and two. The pattern of bond
lengths in 2a suggests that the major contributor to the overall
description of the bonding is mesomer A, and B is much less
important. The lengthening of C(2)–S(3) and the shortening of
C(2)–S(2), C(2)–S(4) and Fe(1)–S(4) distances on alkylation
of S(4) to give [3a]ϩ suggests that the importance of B (Fig. 4,
X = SMeϩ) has increased compared with A.
In contrast to that of 1a, the FeCo2 triangle of 2a is distorted
with considerable elongation of Fe(1)–Co(2), 2.624(3) Å, over
Fe(1)–Co(1), 2.502(3) Å. This is probably a reflection of their
differing electronic environments. The Co–Co distance in 2a,
2.461(4) Å, is also longer than that in 1a, 2.4378(5) Å, and the
sum of the metal–metal bond lengths in 2a (7.587 Å) is greater
than in 1a (7.4564 Å). The distortion of the FeCo2 triangle is
not reflected in the Co–S(1) and Co–C(1) distances though the
former are shorter than in 1a. The other notable consequence
of the formation of the FeSCSC heterocycle is that the Fe(1)–
C(1) bond, 1.881(11) Å, is much shorter in 2a than in 1a,
2.085(2) Å.
The incorporation of the µ3-CS ligand into the heterocyclic
ring results in an increase in the Cµ–S bond length from
1.638(3) to 1.774(10) Å for C(1)–S(2) These and the other C–S
bond lengths, C(2)–S(2) 1.731(11) Å, C(2)–S(4) 1.768(11) Å and
the exocyclic C(2)–S(3) 1.680(11) Å, should be compared with
1.55 Å in CS , 1.611 Å in the thioketone PhC H (Ph)C᎐S, 1.712
᎐
2
6
4
Fig. 4 Resonance forms of 2 (X᎐S) and [3]ϩ (X = SMeϩ).
Å in thiophene, 1.819 Å in thioalkanes18 and the various dis-
tances in the potassium salt of the methyltrithiocarbonate ion
[C–S 1.6624(14) and 1.7100(15) Å; C–SMe 1.7562(14) Å; S–Me
1.800(2) Å; C–S–Me 106.36(9)Њ].19 They indicate that all of the
C–S bonds in 2a have bond orders between one and two, and
that even the shortest has much single bond character and the
longest some double bond character.
᎐
Spectroelectrochemistry
The electrochemical data for 2a and [3a]ϩ are given in Table 3
together with those for 1a, [{Co(η5-C5H5)}2{Fe(CO)2(PPh3)}-
(µ3-S)(µ3-CSMe)]I,[{Co(η5-C5H5)}3(µ3-S)(µ3-CSMe)]Iand[{Co-
(η5-C5H5)}3(µ3-S)(µ3-CS)] which are included to aid our discus-
sion; the last was taken from ref. 22. The voltammetric profiles
for 2a and [3a]I are shown in Fig. 5, and for 1a and [{Co-
(η5-C5H5)}2{Fe(CO)2(PPh3)}(µ3-S)(µ3-CSMe)]I, [1aMe]I, in
Fig. 6. In the following discussion a couple is denoted by a bold
letter, e.g. A, and the non-isolated species involved in the elec-
tron transfer by italicized Roman numerals e.g. I. Scheme 2
summarises the proposed electrochemical scheme using 2a and
[3a]ϩ as examples.
The structure of [{Co(ꢀ5-C5H5)}2{Fe(CO)(PPh3)}(ꢁ3-S)-
(ꢁ3-C2S3Me)]I, [3a]I
The cation of the salt [3a]I (Fig. 2, Table 2) has a struc-
ture similar to that of 2a, but with the exocyclic S atom of the
FeSC(S)SC heterocycle alkylated by Meϩ. This results in a
shortening of most bond lengths within the cluster, except for
Fe(1)–C(1). Within the heterocyclic moiety most bond lengths
decrease except for Fe(1)–C(1) and the exocyclic C(2)–S(3)
which lengthen. In the case of the latter, the increase is from
1.680(11) Å to 1.732(10) Å, but it is still much shorter than
S(3)–C(3)H3 which, at 1.798(9) Å, is a normal single bond. The
C(2)–S(3)–C(3)H3 angle of 104.0(4)Њ is close to the 107.7(4)Њ
Reduction processes. Both neutral clusters, 1a and 2a, display
a chemically reversible one-electron transfer process A/B at
E 0/Ϫ[1a]=Ϫ1.05VandE 0/Ϫ[2a]=Ϫ0.89V,respectively(allpoten-
tials are referenced against decamethylferrocene). These couples
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Fig. 5 Voltammetric profiles for (a) [{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-C2S3)], 2a, and (b) [{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-C2-
S3Me)]I, [3a]I.
areclearlyduetotheformationoftherespectiveradicalanions, I.
There have been electrochemical studies on clusters having
the general formula {Co(η-C5H5)}3(µ3-X)(µ3-Y) where a Co3
triangle is capped on one face by X (= O, S, Se, NSiMe3, etc.)
and on the other by Y (= CO, CS, S, Se, etc.) and they all have
reduction electron transfers at similar potentials to E 0/Ϫ[1a] and
E 0/Ϫ[2a].22,23 This suggests that the unpaired electron is in a
LUMO dominated by the Co(η-C5H5) groups; a proposal
Oxidation processes. An interesting sequence of electron
transfer steps is found in the oxidation electrochemistry of 2a
with its C2S3 ligand. Two anodic one-electron electron transfers
E and G are seen at room temperature and scan rates 50 mV–1
V, Fig. 5(a). The first process E (Epa = 0.66 V) is irreversible and
the radical cation II, [2a]ϩ, undergoes a fast EC process to form
a new species giving rise to feature F; this species is oxidized
back to 2a at Epc = Ϫ0.20 V (Scheme 2). The current ratio iF/iE is
∼0.5 and is independent of scan rate and temperature but varies
with solvent; the potential is temperature-dependent. This is the
classical EC profile for an oxidised species undergoing a struc-
tural rearrangement. In the anodic scan, E is followed by a
chemically and electrochemically reversible one-electron couple
which is supported by an ESR spectrum of 2a Ϫ which showed
ؒ
ill-defined hyperfine coupling to cobalt. Unfortunately, the ESR
spectra were of poor quality even at 77 K despite the apparent
stability of the radical anions on the electrochemical timescale.
Upon methylation of the µ3-CS ligand of 1a to give [{Co-
(η5-C5H5)}2{Fe(CO)2(PPh3)}(µ3-S)(µ3-CSMe)]I, [1aMe]ϩ, or
the exocyclic sulfur of the C2S3 ligand of 2a to give [3a]ϩ, new
one-electron reduction processes C giving species V, appear at
o
G/H at Ep = 1.24 V. A crucial observation is that when exo-
cyclic C᎐S group of 2a is methylated, the species giving rise to F
᎐
is no longer formed and the one-electron GЈ/HЈ couple is the
Ep = Ϫ0.54 and Ϫ0.58 V for [1aMe]ϩ and [3a]ϩ, respectively.
only feature on the anodic scan of [3a]ϩ, Fig. 5(b).
c
[{Co(η5-C5H5)}3(µ3-S)(µ3-CSMe)]I also has this feature in its
electrochemistry (Table 3). This one-electron step is chemically
reversible for [1aMe]ϩ, but not for [3a]ϩ. Further reduction of V
leads to decomposition products and multielectron processes at
potentials > Ϫ1.0 V. The electron transfer step giving rise to V
is attributed to reduction of the cationic CSMe or S2CSMe
moieties, the SOMO being an orbital having a high sulfur con-
tent; this infers that the canonical structure B in Fig. 4 has a
significant contribution to the SOMO.
Clearly, the structural changes that occur during the EC
process cannot be too drastic, nor are E and F due to decom-
position. Furthermore, the electrochemistry shows that the
species formed in the fast EC process can be oxidised at G as
well as the parent 2a. A clue to the EC mechanism is provided
by the work of Moses et al.24 on the electrochemistry of organic
cyclic trithiocarbonates, (T). They found that the monomeric
radical cations Tϩ coupled with unchanged T to give dimeric
ؒ
ϩ
ؒ
T2 . The current functions and potentials they reported are
D a l t o n T r a n s . , 2 0 0 3 , 4 4 7 2 – 4 4 8 1
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Fig. 6 Voltammetric profiles for (a) [{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-CS)], 1a, and (b) [{Co(η5-C5H5)}2{Fe(CO)(PPh3)}(µ3-S)(µ3-CSMe)]I,
[1aMe]I.
Scheme 2 (C5H5 ligands omitted for clarity; L = PPh3.)
D a l t o n T r a n s . , 2 0 0 3 , 4 4 7 2 – 4 4 8 1
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similar to those found for 2a and we propose a similar EC
mechanism (Scheme 2). The exocyclic sulfur of 2a is a good
nucleophile and is therefore capable of attacking the radical
metallovinyl trithiocarbonate or a metallo-1,3-dithiole-2-thione
with a Fe–Cµ double bond.
cation 2a؉ at the electrophilic carbon to give the dimer III
ؒ
Acknowledgements
ؒ
shown in Scheme 2. Because the resultant FeCS2CSC(S )S2CFe
We thank Labkem Ltd. (Dublin) for financial assistance to
A. J. P.; Dr A. L. Reiger and Prof. P. H. Rieger (Brown
University) for assistance with the ESR spectra; the Royal
Society of New Zealand, Marsden Fund, for partial financial
support; and Professor W. T. Robinson and Dr J. Wikaira
(University of Canterbury) for crystallographic data collection.
unit is positively charged, it is reduced at lower potentials (F)
with cleavage of the S C bond returning 2a to the electrode
surface. The one-electron oxidation G is assigned to the form-
ation of the radical cation IV from the dimer where the
unpaired electron is now in a SOMO largely located on the
cluster framework. Overall, the oxidation of 2a to IV is a two-
electron transfer as two moles of 2a are involved. In the case of
[3a]ϩ the SMe group blocks the dimerisation process and a one
electron oxidation G gives the radical dication [3a]2ϩ, VI, in
Scheme 2.
References
1 A. R. Manning, L. O’Dwyer, P. A. McArdle and D. Cunningham,
J. Organomet. Chem., 1998, 551, 139.
2 A. R. Manning and A. J. Palmer, J. Organomet. Chem., 2002, 651,
60.
3 A. R. Manning, A. J. Palmer, J. McAdam, B. H. Robinson and
J. Simpson, Chem. Commun., 1998, 1577.
In order to gain more information on the species associated
with processes F and G ν(CO) spectra were recorded during
electrochemical (OTTLE) and chemical oxidation. Unfortu-
nately, rapid fouling of the electrode occurred during the
OTTLE measurement. Oxidation at 0.60 V gave a new broad
ν(CO) band at 1967 cmϪ1 but this species was unstable
and decomposed rapidly to another with ν(CO) 1871 cmϪ1.
4 H-C. Böttcher, M. Fernandez, M. Graf, K. Merzweiler and
C. Wagner, Z. Anorg. Allg. Chem., 2002, 628, 2247.
5 G. M. Sheldrick. SHELXTL. An integrated system for solving,
refining and displaying crystal structures from diffraction data.
University of Göttingen, Federal Republic of Germany, 1980.
6 SMART CCD software Bruker AXS, Madison WI, 1994.
7 SADABS (correction for area detector data) Bruker AXS Madison
WI, 1997.
8 G. M. Sheldrick, SHELXS-86: A program for the solution of crystal
structures from diffraction data, University of Göttingen, Germany,
1986; G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467–473.
9 G. M. Sheldrick, SHELXS-97: A program for the solution of crystal
structures from diffraction data, University of Göttingen, Germany,
1990.
10 G. M. Sheldrick, SHELXL-97: A program for the refinement of
crystal structures. University of Göttingen, Germany, 1997.
11 D. Coucouvanis, Prog. Inorg. Chem., 1970, 11, 233.
12 H. Werner, K. Leonhard, O. Kolb, E. Röttinger and
H. Vahrenkamp, Chem. Ber., 1980, 113, 1654.
13 J. Fortune and A. R. Manning, Organometallics, 1983, 2, 1719.
14 J. Doherty, J. Fortune, A. R. Manning and F. S. Stephens, J. Chem.
Soc., Dalton Trans., 1984, 1111.
15 N. Bricklebank, P. J. Skabara, D. E. Hibbs, M. B. Hursthouse and
K. M. Abdul Malik, J. Chem. Soc., Dalton Trans., 1999, 3007.
16 M. B. Dinger and W. Henderson, J. Chem. Soc., Dalton Trans., 1998,
1763.
17 N. Cromhout, A. R. Manning and A. J. Palmer, unpublished work.
18 F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen
and R. Taylor, J. Chem. Soc., Perkin Trans. 2, 1987, S1–S19.
19 D. Steuber, A. M. Arrif, D. M. Grant and R. W. Parry, Inorg. Chem.,
2001, 40, 1912.
Chemical oxidation of 2a with [(4-BrC6H4)3N]ϩSbCl6 gave a
Ϫ
clean spectrum with a single ν(CO) band at 1951 cmϪ1, a shift of
26 cmϪ1 from 1925 cmϪ1 for 2a. As one would have expected a
larger shift for a radical cation, it is possible that this spectrum
is due to the dimer cation III. Under the same conditions,
oxidation of [3a]ϩ by chemical or electrochemical means led to
rapid decomposition.
The cyclic voltammetric responses at room temperature
in the anodic direction for 1a (Fig. 6) are similar to those seen
for other M3(µ3-S)(µ3-CS) clusters, e.g. [{Co(η5-C5H5)}3(µ3-S)-
a
(µ3-CS)].22 A one-electron oxidation transfer E occurs at Ep
=
0.50 V and this cation then undergoes a fast EC conversion
(cf. 2a) to another species which gives rise to wave F; this is then
c
reduced back to original cation at Ep = Ϫ0.02 V. When its
µ3-CS ligand is methylated, [1a(Me)]I, this oxidation step is
a
truncated and a new irreversible process GЈ is seen at Ep
=
0.62 V; this is similar to the electrochemistry of [{Co(η5-C5-
H5)}3(µ3-S)(µ3-CSMe)]ϩ. The relative current ratio i(E)/i(GЈ) is
dependent on the scan rate and temperature confirming that GЈ
is derived from E. With its similar electrochemistry to 2a it is
tempting to attribute the EC process for 1a to a dimerisation
reaction.
20 M. Akita, A. Kondoh and Y. Moro-oka, J. Chem. Soc.,
Dalton Trans., 1989, 1627.
21 H. Adams, N. A. Bailey, C. Ridgeway, B. F. Taylor, S. J. Walters and
M. J. Winters, J. Organomet. Chem., 1990, 394, 349.
22 T. Madach and H. Vahrenkamp, Chem. Ber., 1981, 114, 505.
23 R. L. Bedard, A. D. Rae and L. F. Dahl, J. Am. Chem. Soc., 1986,
108, 5924.
Conclusions
The fixation of CS2 by [{Co(η5-C5H5)}2{Fe(CO)(L)2(µ3-S)-
(µ3-CS)], 1, gives [{Co(η5-C5H5)}2{Fe(L)2(µ3-S)(µ3-C2S3)] com-
plexes, 2, in which a trithiocarbonate moiety SC(S)S bridges a
Fe–Cµ edge of the trigonal bipyramidal (µ3-C)FeCo2(µ3-S) clus-
ter. On the basis of structural and spectroscopic data it is con-
cluded that the FeSC(S)SC heterocycle is best regarded as a
24 P. R. Moses, J. Q. Chambers, J. O. Sutherland and D. R. Williams,
J. Electrochem. Soc., 1975, 122, 608.
D a l t o n T r a n s . , 2 0 0 3 , 4 4 7 2 – 4 4 8 1
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