Insertion of bis-ferrocenylbutadiyne into an osmium hydride bond. The synthesis, structure and electrochemical response of Os 4(CO) 11(μ-η- Z-FcCC(H)C 2Fc)(μ-H) 3

Abstract

The reaction of Os 4(CO) 12(μ-H) 4 with Me 3NO followed by 1,4-bis(ferrocenyl)butadiyne ( 1) has yielded the tetraosmium product Os 4(CO) 11(μ-η 2-FcCC(H)C 2Fc)(μ-H) 3 ( 5), Fc=C 5H 5FeC 5H 4 in 9% yield by decarbonylation and insertion of the 1,4-bis(ferrocenyl)butadiyne into one of the metal–hydrogen bonds in the cluster. Compound 5 was characterized by IR, 1H-NMR spectroscopy and single crystal X-ray diffraction analysis. The molecule contains a closed tetrahedral cluster of four osmium atoms with three bridging hydride ligands. One of the C–C triple bonds of 1 was inserted into one of the Os–H bonds to form a (bis-ferrocenyl)yneenyl ligand that bridges one edge of the cluster in a θ-π coordination mode. Compound 5 exhibits two one-electron oxidations for the ferrocenyl groups at E°=+0.443 and +0.486 V versus Ag/AgCl, Δ E°=0.043 V. This small difference indicates that there is little or no electronic communication between the two ferrocenyl groups.