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

Abstract

Two new platinum-triosmium cluster complexes PtOs 3(CO) 9(COD)(μ 4-FcC 4Fc) ( 4) and Pt 2Os 3(CO) 10(COD)(μ 5-FcC 4Fc) ( 5) containing the electroactive 1,4-bis-ferrocenylbutadiyne ligand FcC 4Fc were obtained from the reaction of Os 3(CO) 10(μ 3-FcC 4Fc) ( 3) with Pt(COD) 2. Compounds 4 and 5 were characterized by IR and 1H-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 4Fc ligand in the μ 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°=+0.356 and +0.503 V versus Ag ∣ AgCl, and for 5 at E°=+0.478 and +0.576 V.