Experimental and theoretical studies of carbodiphosphorane-CX2 adducts with unusual bonding situations:: Preparation, crystal structures, and bonding analyses of S2CC(PPh3)2, O2CC(PPh3)2, and [(CO)4MS2CC(PPh3)2] (M = Cr, Mo, W)

We report about the first X-ray structure analyses of the CS2 and CO2 adducts with carbodiphosphorane C(PPh3)(2) and the synthesis and X-ray structure analysis of group 6 carbonyl complexes with compound S2CC(PPh3)(2) as a ligand [(CO)(4)MS2CC(PPh3)(2)] (M = Cr, Mo, W). The nature of the carbon-carbon bonding in X2CC(PPh3)(2) and in the model compounds X2CC(PH3)(2) and the metal-ligand bonding in [(CO)(4)MoS2CC(PH3)(2)] have been analyzed with charge and energy decomposition methods using DFT calculations. Carbodiphosphoranes C(PR3)(2) are double electron pair donors having sigma- and pi-carbon lone-pair orbitals as the two highest occupied MOs.