The activation of carbon disulfide by a cluster. The reaction of the µ3-CS
complex [{Co(h-C5H5)}2{Fe(CO)2PPh3}(m3-S)(m3-CS)] with CS2
Anthony R. Manning,a† Anthony J. Palmer,a John McAdam,b Brian H. Robinsonb and Jim Simpsonb†
a Department of Chemistry, University College, Belfield, Dublin 4 Ireland,
b Department of Chemistry, University of Otago, Dunedin, New Zealand
S
When [{Co(h-C5H5)}2{Fe(CO)2PPh3}(m3-S)(m3-CS)] is re-
fluxed in CS2 solution, it is converted to [{Co(h-C5H5)}2{Fe-
C
S
C
(CO)PPh3}(m3-S){m3-CSC(S)S}] which contains an unusual
S
C
C2S3 bridging ligand.
S
O
Co
Co
Co
Co
C
heat, CS2
O
C
O
C
[{Co(h-C5H5)}2{Fe(CO)2PPh3}(m3-S)(m3-CS)] I is formed
Fe
Fe
2
2
when the h -CS2 ligand in [Fe(PPh3)2(CO)2(h -CS2)] is cleaved
by [Co(h-C5H5)(PPh3)2].1,2 When a solution of this compound
in carbon disulfide is heated to reflux for 12 hours, a further
molecule of CS2 is taken up and CO is lost. The product, II, is
obtained in 75% yield. It is a brown crystalline solid which,
when crystallized from carbon disulfide solution, analyses as
Co2(h-C5H5)2Fe(CO)(PPh3)(S)(CS)·2CS2. This is consistent
with NMR and IR spectroscopic data,‡ but does not define
the actual structure of II which was determined by X-ray
crystallography on a crystal grown from benzene solution
which analyzed as [{Co(h-C5H5)}2{Fe(CO)PPh3}(µ3-
S){µ3-CSC(S)S}]·2C6H6.§ It is illustrated in Fig. 1.
PPh3
PPh3
S
S
I
II
Scheme 1
and a C–S (ca. 1.82 Å in thioethers)3 which is indicative of
delocalised bonding. In particular the µ3-C–S distance in II
[1.774(11) Å] is very long compared with that in I [1.638(3) Å]
or its S-methylated derivative, [{Co(h-C5H5)}2{Fe-
(CO)2PPh3}(µ3-S)(µ3-CSMe)]I, [III]I,2 [1.728(7) Å]. The C–S
distances are all longer than the comparable ones in [Co(h-
C5H5)(CNBut)(S2CNS)].4 The overall reaction which gives rise
to II is shown in Scheme 1. It is reminiscent of that of a thiolate
anion, RS2, which with CS2 forms a thioxanthate anion
[RSCS2]25 and is a reflection of the nucleophilicity of the
µ3-CS ligand which has been illustrated by the ease with which
I is alkylated to III+ salts. The related complex [{Co(h-
C5H5)}3(µ3-S)(µ3-CS)] is also readily alkylated at S to give
[{Co(h-C5H5)}3(µ3-S)(µ3-CSMe)]I, but it does not react with
CS2. This implies that the conversion of I to II takes place
because the first-formed [{Co(h-C5H5)}2{Fe(CO)2PPh3}(µ3-
S)(µ3-CS?CS2] intermediate can undergo CO loss with the
formation of an Fe–S bond which stabilizes the C2S3 ligand.
Analogues of II are obtained when Ph3P in I is replaced by
The molecular structure of II is closely related to that of I1,2
and is based on an FeCo2 triangle capped on one face by a µ3-S
ligand and on the other by a µ3-C atom. The coordination about
5
each of the two Co atoms is completed by a h -C5H5 group
whilst that about Fe is completed by a CO and a Ph3P ligand and
the S* atom of a S*C(S)S moiety which is also bonded to the
µ3-C atom. The coordination about Fe is severely distorted from
that found in I where the Fe(L)3 fragment is more or less
symmetrical with respect to an axis from Fe to the midpoint of
the Co–Co bond. Furthermore the FeCo2 triangle is no longer an
isosceles triangle as it is in I [Fe–Co = 2.5099(6), 2.5061(6) Å]
as Fe(1)–Co(1) at 2.642(3) Å is very much longer than Fe(1)–
Co(2) at 2.502(4) Å.
The C2S3 ligand has no precedent. The various C–S bond
(PhO)3P or Bun P, but not when it is replaced by (MeO)3P. The
lengths lie between those for a CNS (ca. 1.62 Å in thioketones)3
3
extent of this reaction is being investigated at present.
The exocyclic S atom in II is nucleophilic and with
electrophiles E such as Me+(I2) or HgCl2 gives [{Co(h-
C5H5)}2{Fe(CO)PPh3}(µ3-S){µ3-CSC(S?E)S}]
adducts.
These have been characterized by elemental analysis and
spectroscopy.
Attempts to use I to activate other cumulenes such as CO2,
COS and MeNCS have not, as yet, been successful. The only
isolable product has been [{Co(h-C5H5)}3(µ3-S)(µ3-CS)],6
which is a thermal decomposition product of I.
We thank Professor W.T. Robinson, University of Christ-
church, Christchurch, New Zealand for collecting the X-ray
data, and Labkem Ltd. (Dublin) for financial assistance to
A. J. P.
Notes and References
† E-mail: armannin@ollamh.ucd.ie; jsimpson@alkali.otago.ac.nz
‡ Spectroscopic data for II: u(CO) 1922 cm21 (KBr disc); 1H NMR (CDCl3
solution) d 4.11(s) and 4.90(s) (C5H5); 7.40 (m) (PPh3); 13C NMR (CDCl3
solution) d 84.93 and 86.08 (C5H5); 128.3(d), 130.2(s), 133.5(d), 135.0(d)
(PPh3); 218.7 (d, J = 22.2 Hz; CO); 243.4 (d, J = 18.7 Hz; SCS); 346.1 (d,
J = 15.3 Hz; µ3-C) [all downfield from (CH3)4Si; d = doublet].
§ Crystal data for II: C43H37Co2FeOPS4, M = 902.65, monoclinic, space
group P21/n, a = 9.853(13), b = 19.97(2), c = 20.61(2) Å, a = 90, b =
Fig. 1 Structure of {Co(h-C5H5)}2{Fe(CO)(CS2)PPh3}(µ3-S)(µ3-CS)]
Chem. Commun., 1998
1577
Manning, Anthony R.
