OXYGEN-HYDROGEN VERSUS NITROGEN-OXYGEN BOND-CLEAVAGE IN THE OXIDATIVE ADDITION OF OXIMES TO [OS3(CO)10(MECN)2] - CRYSTAL-STRUCTURES OF THE ISOMERS [OS3H(ME2C=NO)(CO)10] AND [OS3(OH)(ME2C=N)(CO)10]

Acetone oxime (Me2CNOH) reacts with [Os3(CO)10(MeCN)2] to give the bridging oximato cluster [Os3(μ-H)(μ-Me2CNO)(CO)10] (1) resulting from oxidative addition with OH 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 (Ph2CNOH), cyclohexanone (C6H10NOH), acetaldehyde (MeCHNOH), benzaldehyde (PhCHNOH) (two isomers obtained), and formamide (NH2CHNOH). Compound 1 isomerises at 125°C to the non-hydrido isomer [Os3(μ-OH)(μ-Me2CN)(CO)10] (2) which was characterised spectroscopically and crystallographically and shown to contain the bridging hydroxy and the N-bonded Me2CN ligands. Overall oxidative addition of the oxime with NO bond cleavage has been achieved by an initial oxidative addition with OH cleavage followed by isomerisation. © 1990.