Exceptional substitutional lability of the ‘raft’ cluster Os6(CO)20NCMe1Dedicated to Professor Brian Johnson on the occasion of his 60th birthday in recognition of his outstanding contribution to organometallic and inorganic chemistry.1

The kinetics of reactions of the planar ‘raft’ cluster Os6(CO)20(NCMe) with a wide variety of P-donor ligands, L, in toluene have been studied. Replacement of NCMe by L proceeds via initial, very rapid and reversible formation of the adducts Os6(CO)20(NCMe)L in a pre-equilibrium step which is followed by relatively slow disssociation of the NCMe ligand. The equilibrium and rate constants vary systematically with the electronic and steric …