[ML<inf>n</inf>(SiR<inf>3</inf>)(η²-H-H)] or [ML<inf>n</inf>(H)(η²-H-SiR<inf>3</inf>)]? An ab initio MO Study on [OsCl(CO)(PR<inf>3</inf>)<inf>2</inf>"H<inf>2</inf>SiR<inf>3</inf>"] complexes

Ab initio MO calculations at the MP2 and MP4 levels on the [OsCl(CO)(PH3)2"H2SiH3"] model system predict the possible existence of two different stable species, one of [OsCl-(CO)(PH3)2(SiH3)(η2-H-H)] nature and another of [OsCl(CO)(PH3)2(H)(η2-H-SiH3)] nature, very close in energy. From data on this particular system, the importance of different energy contributions for the relative stability of [MLn(SiR3)(η2-H-H)] and [MLn(H)(η2-H-SiR3)] complexes is analyzed.