Synthesis and structure of new osmium-PCP complexes. Osmium-mediated C-C bond activation

The new complex Os{1,3-((Pr2PCH2)-Pr-i)(2)C6H3}(Cl)(PPh3) (2) was obtained from the reaction between the diphosphine {1,3-((Pr2PCH2)-Pr-i)(2)C6H4} (1) and OsCl2(PPh3)(3). 2 reacts with H-2 to yield the dihydrido species Os{1,3-((Pr2PCH2)-Pr-i)(2)C6H3}(H)(2)(Cl)(PPh3) (3). Addition of 1 equiv of carbon monoxide to 2 led to the formation of Os{1,3-((Pr2PCH2)-Pr-i)(2)C6H3}(CO)(Cl)(PPH3) (4), while in the presence of excess CO, the bis-carbonyl complex Os{1,3-((Pr2PCH2)-Pr-i)(2)C6H3}(CO)(2)-(Cl) (5) was formed. Both 2 and 5 were structurally characterized by X-ray diffraction studies. The reaction of OsCl2(PPh3)(3) (under hydrogen pressure) and OsHCl(PPh3)(3) with the diphosphine {1,3,5-(CH3)(3)-2,6-((Pr2PCH2)-Pr-i)(2)C6H} (6) led to the formation of the C-C activation products Os{3,5-(CH3)-2,6-((Pr2PCH2)-Pr-i)(2)C6H}(H-2)(Cl) (7) and Os{3,5-(CH3)-2,6-(Pr-i(2)-PCH2)(2)C6H}(Cl)(PPh3) (8), respectively.