Cyclometalated osmium complexes containing a tridentate PCP ligand

Reactions between [Et4N](2)OsCl6 and 1,3-(CH2PBu2t)(2)C6H4 afforded the 16- e chloride complexes OsCl(CO)(PCP) (1) and OsH2Cl(PCP) (2) (PCP = [2,6-(CH2 PBu2t)(2)C6H3](-)) in methanol/isoamyl alcohol and 2-propanol, respectively . The iodide OsH2I(PCP) (3) was obtained from 2 in methyl iodide. Treatment of 1 and 2 with [BH4](-) gave the hydride and dihydrogen compounds OsH(CO) (PCP) (4), OsH(H-2)(CO)(PCP) (5), and OsH3(H-2)(PCP) (6), while formation o f the dihydrogen complexes Qs(H-2)(2)Cl(PCP) (7a) and OsH2(H-2)Cl(PCP) (7b) was observed by NMR in solution of 2 under H-2. The structures of 1, 2, an d 3 were determined by X-ray crystallography.