Triosmium clusters containing ligands derived from tropone (cycloheptatrienone): molecular structure of an oxidative addition product [Os3H(µ3-C7H5O)(CO)9]

Abstract

Tropone (cycloheptatrienone, C₇H₆O) reacts in refluxing cyclohexane with [Os₃H₂(CO)₁₀] to give the oxidative addition product [Os₃H(C₇H₅O)(CO)₁₀](1), also formed from [Os₃(CO)₁₀(MeCN)₂], and the insertion product [Os₃H(C₇H₇O)(CO)₁₀](2). Structures based on spectroscopy are discussed. Compound (1) decarbonylates to [Os₃H(C₇H₅O)(CO)₉](3), the X-ray structure of which shows that the µ₃-troponyl ligand is involved in a µ-η²-vinyl type bridge between two Os atoms and a donation through the oxygen atom of the ketonic group to the third Os atom. Hydrogenation of cluster (1) and decarbonylation of cluster (2) lead to the derivatives [Os₃H₂(C₇H₆O)(CO)₉](4) and [Os₃(C₇H₈O)(CO)₉](5). Cluster (4) is directly related to the reported structures [Os₃H₂(C₆H₄O)(CO)₉] from phenol and [Os₃H₂(C₆H₈O)(CO)₉] from cyclohexanone. All five products from tropone contain Os–O bonds and the chemistry is quite unlike any known tropone–transition metal chemistry.