Substitution reactions of [{Co(η5-C5H5)}2{Fe(CO)2(PPh3)}(μ3-S)(μ3-CS)]

On heating, the cluster [{Co(η5-C5H5)}2{Fe(CO)2(PPh3)}(μ3-S)(μ3-CS)], 1a, reacts with PR3 ligands (R=(b) MeO, (c) PhO and (d) Bun) by replacement of PPh3 to give [{Co(η5-C5H5)}2{Fe(CO)2(PR3)}(μ3-S)(μ3-CS)], 1b–d, and with CNR (R=(e) Me, (f) 2,4,6-Me3C6H2 and (g) 2,6-Cl2C6H3) by replacement of PPh3 and then CO to give [{Co(η5-C5H5)}2{Fe(CO)2(CNR)}(μ3-S)(μ3-CS)], 1e–g, and [{Co(η5-C5H5)}2{Fe(CO)(CNR)2}(μ3-S)(μ3-CS)], 2e–g. These reactions are successful only under a very limited range of conditions, i.e. with a large excess of the incoming ligand and very short reaction times and/or moderate temperatures. The CO ligands in [{Co(η5-C5H5)}2{Fe(CO)2(CNR)}(μ3-S)(μ3-CS)] are labile and may be replaced by more CNR in a reversible reaction or by PPh3 to give, respectively, [{Co(η5-C5H5)}2{Fe(CO)(CNR)2}(μ3-S)(μ3-CS)], 2e–g, and [{Co(η5-C5H5)}2{Fe(CO)(CNR)(PPh3)}(μ3-S)(μ3-CS)], 2h (R=2,6-Cl2C6H3). The IR spectra of the clusters have been studied and for the first time the absorption band in each due to the ν(CS) vibration of the μ3-CS ligand has been identified unambiguously. Its frequency depends on the FeL3 ligand set in a predictable way and lies in the range 1022–1041 cm−1. In the 13C-NMR spectra the μ3-C atom gives rise to resonances between δ 354 and 359. The clusters do not undergo bridge–terminal ligand site exchange. In particular, there is no evidence for the formation of isomers, which contain terminal CS and μ3-CNR ligands.