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

On heating, the cluster [{CO(eta(5) -C5H5)}(2){Fe(CO)(2)(PPh3)}(mu(3)-S)(mu(3)-CS)], 1a, reacts with PR3 ligands (R = (b) MeO, (c) PhO and (d) Bu-n) by replacement of PPh3 to give [{Co(eta(5) -C5H5)}(2){Fe(CO)(2)(PR3)}(mu(3)-S)(mu(3)-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(eta(5)-C5H5)}(2){Fe(CO)(2)(CNR)}(mu(3)-S)(mu(3)-CS)], 1e-g, and [{Co(eta(5)-C5H5)}(2){Fe(CO)(CNR)(2)}(mu(3)-S)(mu(3)-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(eta(5)-C5H5)}(2)Fe(CO)(2)(CNR)}(mu(3)-S)(mu(3)-CS)] are labile and may be replaced by more CNR in a reversible reaction or by PPh3 to give, respectively, [{Co(eta(5)-C5H5)}(2){Fe(CO)(CNR)(2)} (mu(3)-S)(mu(3)-CS)], 2e-g, and [{Co(eta(5)-C5H5)}(2)-Fe(CO)(CNR)(PPh3) (mu(3)-S)(mu(3)-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 v(CS) vibration of the mu(3)-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 C-13-NMR spectra the mu(3)-C atom gives rise to resonances between 5 354 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 mu(3)-CNR ligands. (C) 2002 Elsevier Science B.V. All rights reserved.