The synthesis, structure, and reactivity of the osmium(IV) trihydrido silyl complex, OsH3(SiMe3)(CO)(PPh3)2

Reaction between the five coordinate complex, Os(Ph)Cl(CO)(PPh3)2, and HSiMe3 produces the osmium(IV) trihydrido silyl complex, OsH3(SiMe3)(CO)(PPh3)2 (1). The structure of 1 has been determined by single crystal X-ray crystallography and by multi-nuclear NMR spectroscopy. The structure has an approximately tetrahedral disposition of silyl, carbonyl and the two PPh3 ligands about osmium with the three classical hydride ligands located, one trans to CO, and the other two each approximately trans to a PPh3. Treatment of complex 1 with HSiR3 (R=Et, Ph), HSn(p-tolyl)3, or HC2Ph gives OsH3(SiR3)(CO)(PPh3)2 (R=Et (2), Ph (3)), OsH2[Sn(p-tolyl)3]2(CO)(PPh3)2 (4) or OsH(C2Ph)(CO)(PPh3)3 (5), respectively. A likely intermediate in these reactions is the coordinatively unsaturated complex, OsH2(CO)(PPh3)2.