Towards a catalytic hydrogenolysis of silicon-silicon bonds: Formation of Si–H bonds from disilanes and H2 at platinum

Abstract

Reactions of the disilanes Cl2MeSiSiMeCl2, ClMe2SiSiMe2Cl and Me3SiSiMe3 led to the products of oxidative addition cis-[Pt(SiMeCl2),(PEt3)2] (2), cis-[Pt(SiMe2Cl)2(PEt3)2] (3) and cis-[Pt(SiMe3)2(PEt3)2] (4). Complex cis-[Pt(SiMe2Cl)2(PEt3)2] (3) converts in the presence of dihydrogen into two equivalents HSiMe2Cl and complex trans-[PtH2(PEt3)2] (10). NMR investigations reveal the initial formation of trans-[PtH(SiMe2Cl)(PEt3)2] (5) and one equivalent HSiMe2Cl.

SiSi and SiO Bond Activation at Platinum: Stepwise Formation of a SiH3 Complex

“…The cleavage of a Si À O bond at a silyl ligand to form a silyl(silylene) complex was also proposed by Tilley et al [23] might also be stabilized by an intramolecular interaction from an alkoxy group of the neighboring silyl ligand with the silylene silicon atom. [24] Treatment of complex 4 with hydrochloric acid gave SiH 4 and [Pt(Cl) 2 (dcpe)] (7) (Scheme 4). This conversion completes a cyclic process for the formation of SiH 4 from HSi(OMe) 3 or HSi(OEt) 3 , because 1 can again be synthesized by treatment of 7 with lithium triethylborohydride.…”

“…The 29 Si{ 1 H} NMR spectrum shows a singlet at d = À95.66 ppm, which is accordance with the literature. [26] In conclusion, we have synthesized the bis(silyl) complexes [Pt{Si(OR) 3 (4) reacts with HCl to give the silane SiH 4 . We believe that in future studies, the SiH 3 ligand can be used as a building block in Si À C coupling reactions.…”

“…[3] With regard to the silylation reactions, the oxidative addition of Si À Si bonds at platinum complexes often leads to the generation of bis(silyl) complexes. [2,4] In contrast, Si 2 H 6 as the simplest substrate reacts with [Pt(H) 2 (dcpe)] (dcpe = 1,2-bis(dicyclohexylphosphino)ethane) to form [Pt 2 (m-SiH 2 ) 2 -(dcpe) 2 ]. The SiH 3 complex [Pt(SiH 3 ) 2 (dcpe)] (4) was described to be an intermediate.…”

“…This observation is in contrast to activation reactions of SiÀH bonds at platinum(0) complexes. [16,18] For instance, treatment 4 . [19] The 29 Si{ 1 H} NMR spectrum for 4 shows a doublet of doublets at d = À72.4 ppm with 195 Pt satellites that are due to couplings to phosphorus atoms in the cis and trans position.…”

“…[ 4 by repetitive Si À O bond activation, resulting in hydrodealkoxylations. [11] Moreover, intermediates for the formation of 4 were identified by NMR spectroscopy and give an insight into the rearrangement reactions.…”