Mixed metal cluster complexes containing the bis-ferrocenylbutadiyne ligand: their structures and electrochemical responses

Two new platinum-triosmium cluster complexes PtOs3(CO)(9)(COD)(mu (4)-FcC(4)Fc) (4) and Pt2Os3(CO)(10)(COD)(mu (5)-FcC(4)Fc) (5) containing the electroactive 1,4-bis-ferrocenylbutadiyne ligand FcC(4)Fc were obtained from the reaction of Os-3(CO)(10)(mu (3)-FcC(4)Fc) (3) with Pt(COD)(2). Compounds 4 and 5 were characterized by IR and H-1-NMR spectroscopy, by single crystal X-ray diffraction analysis and by differential pulse voltammetry. Compound 4 consists of a butterfly cluster of one platinum and three osmium atoms with the platinum atom in one of the wing-tip positions. The cluster is co-ordinated to one of the C-C triple bonds of the FcC(4)Fc ligand in the mu (4)-bonding mode. Cluster 5 exhibits the bow tie structure for five metal atoms: two of platinum and three of osmium. Both triple bonds of the butadiyne ligand are co-ordinated in this complex. Both products show two one electron oxidations for the ferrocenyl groups: for 4 at E degrees = + 0.356 and + 0.503 V versus Ag \ AgCl, and for 5 at E degrees = + 0.478 and + 0.576 V. (C) 2001 Elsevier Science B.V. All rights reserved.