Osmadisiloxane and osmastannasiloxane complexes derived from silanolate complexes of osmium(II)

Treatment of the five-coordinate chlorodimethylsilyl complex, Os(SiMe2Cl)Cl(CO)(PPh3)2 with hydroxide readily produces Os(SiMe2OH)Cl(CO)(PPh3)2 (1). Complex 1 is deprotonated by tBuLi giving the silanolate complex, Os(SiMe2OLi)Cl(CO)(PPh3)2 (2), which reacts further with Me3SiCl or Me3SnCl to give Os(SiMe2OSiMe3)Cl(CO)(PPh3)2 (3) or Os(SiMe2OSnMe3)Cl(CO)(PPh3)2 (4), respectively. The structures of 3 and 4 have been determined by X-ray crystallography. Reaction between OsH(κ2-S2CNMe2)(CO)(PPh3)2 and HSiMe2Cl gives Os(SiMe2Cl)(κ2-S2CNMe2)(CO)(PPh3)2 (5). This six-coordinate chlorodimethylsilyl complex, is unreactive towards hydroxide at room temperature and at 60 °C forms Os[Si(OH)3](κ2-S2CNMe2)(CO)(PPh3)2 (7). Complex 5 is, however, smoothly converted to the hydroxy derivative, Os(SiMe2OH)(κ2-S2CNMe2)(CO)(PPh3)2 (6) upon chromatography on silica gel. Complex 6 is deprotonated by tBuLi giving the intermediate silanolate complex, Os(SiMe2OLi)(κ2-S2CNMe2)(CO)(PPh3)2, which reacts further with Me3SiCl to give Os(SiMe2OSiMe3)(κ2-S2CNMe2) (CO)(PPh3)2 (8). Crystal structure determinations for 5, 6, 7, and 8 have been obtained and structural comparisons of these related compounds are made.