Variation of the electron population by four units in the cluster series [(η5-Cp′)3Mo3S4Co(L)]n+ (L = I, CO, PPh3, NO; n = 0, 1)

The versatility of cuboidal Mo3S4Co clusters for the preparation of complexes with different numbers of valence shell electrons (VSE) in the cluster is described. The reaction of the geometrically incomplete cuboidal cluster salt [(η5-Cp′)3Mo3S4][pts] (pts = p-toluenesulfonate) with one molar equivalent of [Co2(CO)8] afforded almost quantitatively the electroneutral 60 VSE cluster [(η5-Cp′)3Mo3S4Co(CO)] (1), which previously has been prepared in low yield by Curtis et al. in autoclave syntheses [M.D. Curtis, U. Riaz, O.J. Curnow, J.W. Kampf, Organometallics 14 (1995) 5337]. Cluster 1 was also obtained in high yield by reaction of [(η5-Cp′)3Mo3S4][pts] with [(η5-Cp∗)Co(CO)2]. Reaction of [(η5-Cp′)3Mo3S4][pts] with two molar equivalents of [Co(I)(CO)3(PPh3)] led to a complex mixture of products, of which the electron deficient 58 VSE cluster salt [(η5-Cp′)3Mo3S4Co(I)][Co(I)3(thf)] ([2][Co(I)3(thf)]) was isolated as single crystals. In the crystal structures of 1 and [2][Co(I)3(thf)], the Co–Mo bond lengths are almost identical, indicating a delocalization of the electron deficiency in [2]+. The reduced form of [2]+, [(η5-Cp′)3Mo3S4Co(I)] (2), was prepared by oxidative substitution of the carbonyl ligand in 1 by I2. Further reactions of 1 with PPh3 and NO leading to the 60 and 61 VSE cluster complexes [(η5-Cp′)3Mo3S4Co(PPh3)] (3) and [(η5-Cp′)3Mo3S4Co(NO)] (4), respectively, enabled the preparation of Mo3S4Co clusters in altogether four different oxidation states.