Transition metal compounds containing bis(dicyclohexylphosphino)methane ligation

The reaction of Mn$\sb2$(CO)$\sb{10}$ with bis(dicyclohexylphosphino)methane (dcpm) in hydrocarbon solvents gives both Mn$\sb2$(CO)$\sb8$(dcpm) (1) and Mn$\sb2$(CO)$\sb6$(dcpm)$\sb2$ (2). Compound (2) decarbonylates under photolysis conditions to yield Mn$\sb2(\mu$-CO)(CO)$\sb4$(dcpm)$\sb2$ (3). The solid state structures of compounds (1) and (2) show a distorted octahedral geometry around the metal centers. The solid state structure of compound (3) reveals a 4-electron donating, asymmetrically bridging carbonyl ligand. The synthesis and structure of these new compounds as well as their spectroscopic properties are discussed and compared to analogous compounds with different binucleating ligands. Compound (3) reacts with some isocyanides to give derivatives; the t-butylisocyanide derivative has been characterized by infrared and NMR spectroscopy. Simple ligand substitution of ReOCl$\sb3$(PPh$\sb3)\sb2$ with dcpm yields ReOCl$\sb3$(dcpm) (4). Reduction of compound (4) with NaBH$\sb4$ produces ReH$\sb7$(dcpm) (5) which has been characterized by NMR spectroscopy. The hydride ligands of compound (5) exhibit H-D exchange when heated in deuterated benzene