Synthesis and Reactivities of Polyhydrido Osmium Arylsilyl Complexes Prepared from OsH₃Cl(PPh₃)₃

Abstract

Reactions of silanes with transition-metal complexes are of interest because their relevance to Si−H bond activation, the structural properties of polyhydrides, and catalytic hydrosilylation reactions. This work presents the results derived from reactions of arylsilanes Ph 2 SiH 2 and PhSiH 3 with OsH 3 Cl(PPh 3 ) 3 (1). Reaction of 1 with 1 equiv or excess Ph 2 SiH 2 affords OsH 3 (SiClPh 2 )(PPh 3 ) 3 (2) or OsH 4 (SiClPh 2 )-(SiHPh 2 )(PPh 3 ) 2 (3), respectively. These silyl complexes are formed via the oxidative addition of Si−H bonds and H/Cl exchange via silylene intermediates. Similarly, reaction of 1 with excess PhSiH 3 produced the analogous bis(silyl) complex OsH 4 (SiClHPh)(SiH 2 Ph)(PPh 3 ) 2 (4). The bis(silyl) complexes are dodecahedral tetrahydride complexes containing weak Si•••H interactions. The complex 3 reacts with PPh 3 and CH 3 CN to selectively eliminate Ph 2 SiH 2 . Computational studies show that the preference for reductive eliminations from 3 follows the order Ph 2 SiH 2 > H 2 > Ph 2 SiHCl > Ph 2 HSi-SiClPh 2 .

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

“…The coordination of the nitrogenous Lewis bases yields tetrahydride compounds of the class OsH 4 (P i Pr 3 ) 2 L, whereas the boranes afford the trihydride‐dihydroborate complexes OsH 3 {κ 2 ‐ H , H ‐(H 2 BR 2 )}(P i Pr 3 ) 2 . In contrast to A , the related chloride OsH 3 Cl(PPh 3 ) 3 reacts with diphenylsilane to give OsH 3 (SiClPh 2 )(PPh 3 ) 3 and OsH 4 (SiClPh 2 )(SiHPh 2 )(PPh 3 ) 2 and with phenylsilane to afford OsH 4 (SiClHPh)(SiH 2 Ph)(PPh 3 ) 2 [32] …”

“…In contrast to A, the related chloride OsH 3 Cl(PPh 3 ) 3 reacts with diphenylsilane to give OsH 3 -(SiClPh 2 )(PPh 3 ) 3 and OsH 4 (SiClPh 2 )(SiHPh 2 )(PPh 3 ) 2 and with phenylsilane to afford OsH 4 (SiClHPh)(SiH 2 Ph)-(PPh 3 ) 2 . [32] The metathesis between the σ-bonds SiÀ C(sp n ) and C(sp 3 )À H of 2 (n = 3) and 3 (n = 2), to yield 4 and 5, can be rationalized as a two-step process. The first of them should involve the reductive elimination of RÀ H from 2 and 3, to give tetrahydride-osmium(IV)-silylene intermediates OsH 4 -(=SiR 2 )(P i Pr 3 ) 2 (B in Scheme 2).…”

Silyl-Osmium(IV)-Trihydride Complexes Stabilized by a Pincer Ether-Diphosphine: Formation and Reactions with Alkynes

“…Consequently, activations involving E–H bonds are favored since the initial coordination number and oxidation of the metal center are rapidly restored after the activation, by removal of molecular hydrogen. Among the activated E–H bonds, the C–H bonds are predominant. , On the other hand, the Si–H bond activation has received scarce attention, although some silyl-metal-polyhydride derivatives are known mainly for osmium and iridium . Like the metal-mediated C–H bond cleavage, the Si–H bond activation takes place via σ-intermediates, where the Si–H bond coordinates to the metal center.…”

Combined high resolution X-ray and DFT Bader analysis to reveal a proposed Ru–H⋯Si interaction in Cp(IPr)Ru(H)2SiH(Ph)Cl

“…However, a reverse situation can be observed as well where a TM bound hydrogen could interact with suitable Lewis acids like, for example, group 13 elements or silicon as an example of a group 14 element. [7][8][9][10][11][12] Some examples include the LFe(H)2BH2 compound which bears similarities to the B2H6 mentioned before. [13] Another example would be the recently suggested reaction product of a Ru complex with HSiR3 where the authors note an interaction between the Ru-H and the Si in the solid state.…”