Isomerization of the diphosphine ligand 3,4-bis(diphenylphosphino)-5-methoxy-2(5H)-furanone (bmf) at a triosmium cluster and P-C bond cleavage in the unsaturated cluster 1,1-Os3(CO)9(bmf): Synthesis and X-ray diffraction structures of the isomeric Os3(CO)

The triosmium cluster Os3(CO)10(MeCN)2 reacts with 3,4-bis(diphenylphosphino)-5-methoxy-2(5H)-furanone (bmf) at room temperature to give the diphosphine-bridged cluster 1,2-Os3(CO)10(bmf). Isomerization of the bmf ligand takes place at elevated temperature (358-383 K) to afford an equilibrium mixture (15:85) of 1,2- and 1,1-Os3(CO)10(bmf). Thermolysis (>383 K) of the isomeric Os3(CO)10(bmf) clusters ultimately furnishes the benzyne-substituted clusters HOs3(CO)8(μ-C6H4)(μ-C23H19O3P2) as a mixture of two diastereomers. The X-ray structure of the major benzyne-substituted diastereomer has confirmed the locus of the P-C bond cleavage attendant in this reaction.