Synthesis of triosmium alkylidyne clusters incorporating bis(diphenylphosphino) alkane type ligands. Crystal structures of [{Os3(μ-H)2(CO)9(μ3-C)}2(μ-dppp)] (dppp = bis(diphenylphosphino)propane) and [Os3(μ-H)2(CO)8(μ3-CPPh2CH2PPh2)]

Abstract

The reaction of triosmium alkylidyne cluster [Os3(μ-H)3(CO)9(μ3-CCl)] with excess bis(diphenylphosphino)methane (dppm), bis(diphenylphosphino)ethane (dppe) or bis(diphenylphosphino)propane (dppp) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (dbu) yields [Os3(μ-H)2(CO)9(μ3-CPPh2CH2PPh2)]1, [Os3(μ-H)2(CO)9(μ3-CPPh2CH2PPh2)]2, and a linking cluster [{Os3(μ-H)2(CO)9(μ3-C)}2(μ-dppp)]3 respectively in moderate yields. Complexes 1 and 2 are found to undergo ring formation by decarbonylation and formation of an Os-P bond to give new clusters [Os3(μ-H)2(CO)8(μ3-CPPh2CH2PPh2)]4 and [Os3(μ-H)2(CO)8(μ3-CPPh2CH2CH2PPh2)]5. Single-crystal X-ray structural analyses of 3 and 4 have shown that there was a phosphine-substituted μ3-C ligand bonded to one of the triosmium metal cores, giving a five-membered osmacycle complex for 4, while 3 has the structure of a linking cluster, with the two triosmium alkylidyne cluster units linked by a dppp ligand.