Metathesis between E-C(spⁿ ) and H-C(sp³ ) σ-Bonds (E=Si, Ge; n=2, 3) on an Osmium-Polyhydride.

ABSTRACT: The silylation of a phosphine of OsH₆ (Pⁱ Pr₃ )₂ is performed via net-metathesis between Si-C(spⁿ ) and H-C(sp³ ) σ-bonds (n=2, 3). Complex OsH₆ (Pⁱ Pr₃ )₂ activates the Si-H bond of Et₃ SiH and Ph₃ SiH to give OsH₅ (SiR₃ )(Pⁱ Pr₃ )₂ , which yield OsH₄ {κ¹ -P,η² -SiH-[ⁱ Pr₂ PCH(Me)CH₂ SiR₂ H]}(Pⁱ Pr₃ ) and R-H (R=Et, Ph), by displacement of a silyl substituent with a methyl group of a phosphine. Such displacement is a first-order process, with activation entropy consistent with a rate determining step occurring via a highly ordered transition state. It displays selectivity, releasing the hydrocarbon resulting from the rupture of the weakest Si-substituent bond, when the silyl ligand bears different substituents. Accordingly, reactions of OsH₆ (Pⁱ Pr₃ )₂ with dimethylphenylsilane, and 1,1,1,3,5,5,5-heptamethyltrisiloxane afford OsH₅ (SiR₂ R')(Pⁱ Pr₃ )₂ , which evolve into OsH₄ {κ¹ -P,η² -GeH-[ⁱ Pr₂ PCH(Me)CH₂ SiR₂ H]}(Pⁱ Pr₃ ) (R=Me, OSiMe₃ ) and R'-H (R'=Ph, Me). Exchange reaction is extended to Et₃ GeH. The latter reacts with OsH₆ (Pⁱ Pr₃ )₂ to give OsH₅ (GeEt₃ )(Pⁱ Pr₃ )₂ , which loses ethane to form OsH₄ {κ¹ -P,η² -GeH-[ⁱ Pr₂ PCH(Me)CH₂ GeEt₂ H]}(Pⁱ Pr₃ ).

SUBMITTER: Esteruelas MA 

PROVIDER: S-EPMC9401005 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature