Synthesis, characterisation and electrochemical analysis of a bis(ferrocenyl) vinyl allyl ether-substituted triosmium cluster

Abstract

From the reaction of [Os₃(CO)₁₀(MeCN)₂] with ethynylferrocene was isolated the known cluster [Os₃(CO)₁₀{(C₅H₅)FeC₅H₄CCH}]1; in addition the bis(ferrocenyl)-substituted triosmium cluster [Os₃(CO)₉{[(C₅H₅)FeC₅H₄CCH]₂CO}]2 was obtained in reasonable yield. Both ¹H and ¹³C-{¹H} NMR studies of 2 indicate that the ferrocenyl groups are inequivalent. A single-crystal X-ray analysis of 2 showed that on co-ordination to the triosmium cluster the two ethynylferrocene groups have been linked via a metal carbonyl to give a composite ligand that may be described as a 2,6-bis(ferrocenyl) vinyl allyl ether. An electrochemical analysis of the compounds (C₅H₅)FeC₅H₄CCH, 1 and 2 reveals reversible one-electron oxidations attributable to the ferrocenyl moiety, with the two well separated redox processes found in 2 indicating inequivalent ferrocenyl sites. In addition, irreversible two-electron cluster-based oxidation processes were observed for 1 and 2.