Triosmium clusters derived from aldehydes, ketones, and ketens and their interconversions

Abstract

Acyl and enolato-complexes of types [Os₃(CO)₁₀(µ-OCR)H](R = CH₃, C₅H₁₁, C₆H₁₃, PhCH₂, Me₂CH, or Ph) or [Os₃(CO)₁₀(µ-OCHCR′₂)H](R′= H, Me, or Ph) have been obtained by oxidative addition of aldehydes at [Os₃(CO)₁₂] or by insertion of keten or substituted ketens into an Os–H bond of [Os₃(CO)₁₀H₂]. In certain cases the interconversion of enolato- and acyl complexes was established and in other cases inferred from their reactivity. The acyl complexes where R = CH₃, Ph, or Ph₂CH (derived from isomerisation of the enolato-complex where R = Ph) decarbonylate at the ligand to give products derived from the alkyl complexes formed. Most acyl complexes (R = CH₃, C₅H₁₁, C₆H₁₃, or PhCH₂) decarbonylate, however, only at the metal with subsequent hydrogen-atom transfer to and from the ligand to give complexes of type [Os₃(CO)₉(µ₃-R″CCHO)H₂] containing a co-ordinated formyl group. Analogous species were obtained from cyclohexanone and [Os₃(CO)₁₂] or from cyclohexenone and [Os₃(CO)₁₀H₂]. All the complexes with organic ligands containing oxygen have Os–O bonds.