Synthesis and reactivity studies of the diphosphine ligand 2-(ferrocenylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (fbpcd): Bridge-to-chelate ligand isomerization kinetics in Os3(CO)10(fbpcd) and X-ray diffraction structure of the ortho-met

The synthesis of the new diphosphine ligand 2-(ferrocenylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (fbpcd) is described. The fbpcd ligand reacts with 1,2-Os3(CO)10(MeCN)2 to give the diphosphine-bridged cluster 1,2-Os3(CO)10(fbpcd) (2b) as the principal product (>80%). Thermolysis of 2b promotes the isomerization of the fbpcd ligand and formation of the chelating isomer 1,1-Os3(CO)10(fbpcd) (2c). Near-UV photolysis of 2c leads to the formation of the hydride-bridged cluster HOs3(CO)9[μ-PhP(C6H4)CC(PPh2)C(O)CCH(C5H4FeCp)C(O)] (3). All new compounds have been isolated and fully characterized by IR and NMR spectroscopies and X-ray diffraction analysis in the case of cluster 3.