Oxygenhydrogen versus nitrogenoxygen bond cleavage in the oxidative addition of oximes to [Os 3(CO) 10(MeCN) 2]: crystal structures of the isomers [Os 3H(Me 2CNO)(CO) 10] and [Os 3(OH)(Me 2CN) (CO) 10

Abstract

Acetone oxime (Me 2CNOH) reacts with [Os 3(CO) 10(MeCN) 2] to give the bridging oximato cluster [Os 3(μ-H)(μ-Me 2CNO)(CO) 10] ( 1) resulting from oxidative addition with OH bond cleavage. An X-ray crystal structure determination showed that the oximato ligand is bridging two osmium atoms by bonding to one Os atom through the N-atom and to another through the O-atom. A range of clusters with similarly bonded oximato ligands were synthesised from the oximes derived from benzophenone (Ph 2CNOH), cyclohexanone (C 6H 10NOH), acetaldehyde (MeCHNOH), benzaldehyde (PhCHNOH) (two isomers obtained), and formamide (NH 2CHNOH). Compound 1 isomerises at 125°C to the non-hydrido isomer [Os 3(μ-OH)(μ-Me 2CN)(CO) 10] ( 2) which was characterised spectroscopically and crystallographically and shown to contain the bridging hydroxy and the N-bonded Me 2CN ligands. Overall oxidative addition of the oxime with NO bond cleavage has been achieved by an initial oxidative addition with OH cleavage followed by isomerisation.