Dehydrogenative Coupling of a Tertiary Silane Using Wilkinson's Catalyst

Abstract

Wilkinson's catalyst [Rh(PPh3)3Cl] results active in the dehydrogenative coupling of the tertiary silane SiMeH(o‐C6H4SMe)2 (L1) to give (o‐C6H4SMe)2MeSi–SiMe(o‐C6H4SMe)2 (L2). The stoichiometric reaction of [Rh(PPh3)3Cl] with L1 affords a new silyl‐hydrido‐RhIII complex [Rh(H){SiMe(o‐C6H4SMe)2}Cl(PPh3)] (1), which results also active in the dehydrocoupling of L1. The unsaturated RhIII compound [Rh(H){SiMe(o‐C6H4SMe)2}(PPh3)][BArF4] (2) was synthesized by reaction of 1 with NaBArF4 and shows lower catalytic activity in this process. Compound 2 reacts with a second equivalent of L1 to form [Rh{SiMe(o‐C6H4SMe)2}2][BArF4] (3), which is inactive in catalysis. Our results allow proposing 1 as an active species in the catalytic reaction and suggesting the formation of 3 as a deactivation process when the unsaturated compound 2 is used as catalyst.

Rhodium(III) Catalyzed Solvent‐Free Tandem Isomerization–Hydrosilylation From Internal Alkenes to Linear Silanes

“…ESI–MS (Electrospray ionisation mass spectroscopy) shows a molecular ion at m / z= 809.15 with the correct isotope pattern for the [Rh(H){SiMe 2 ( o ‐C 6 H 4 SMe)}(PPh 3 ) 2 ] + fragment (see Supporting Information for more details). The spectroscopic data suggests a square–pyramidal structure for 1 , with a strong σ‐donor silyl fragment trans to the vacant octahedral site, as in the related compound 3 and as expected for d 6 pentacoordinated complexes …”

“…We have recently reported the reaction of [Rh(PPh 3 ) 3 Cl] with a hydrosilane–thioether tridentate proligand that yields a silyl–hydrido–Rh III complex ( 2 in Figure ). Furthermore, we also reported the synthesis of a cationic species derived from 2 , upon exchange of the chlorido by a bulky and non‐coordinated counter‐anion [BAr F 4 ] − [Ar F =3,5‐(CF 3 ) 2 C 6 H 3 ] ( 3 in Figure ) . In a similar way, the reaction of [Rh(PPh 3 ) 3 Cl] with a molecular amount of the bidentate proligand SiMe 2 H( o ‐C 6 H 4 SMe) and NaBAr F 4 in CH 2 Cl 2 at room temperature, afforded, after 30 min, the air stable cationic compound {Rh(H)[SiMe 2 ( o ‐C 6 H 4 SMe)](PPh 3 ) 2 }[BAr F 4 ] ( 1 ) (Scheme ).…”

“… Catalysts used in this work; Wilkinson ’s catalyst, 1 (synthesized and characterized in this work), 2 and 3 (synthesized previously in our group) …”

From Remote Alkenes to Linear Silanes or Allylsilanes depending on the Metal Center

“…Here, we report on the catalytic activity of the coordinatively unsaturated Rh III compound [RhH{SiMe( o ‐C 6 H 4 SMe) 2 }(PPh 3 )][BAr F 4 ] ( 1 , Figure ) in the tandem isomerization–hydrosilylation of internal alkenes to form linear silanes. Moreover, we describe the synthesis and characterization of coordinatively saturated Ir III compounds 2 – 4 (Figure ).…”

Synthesis of a Fragment of Crystalline Silicon: Poly(Cyclosilane)

“…The molecule is found at sites of inversion symmetry and only one half of the molecule is crystallographically independent. [31][32][33][34] Dehydrocoupling is a step-growth polymerization in which the first Si À Si bond formation converts two primary silanes into a less-reactive secondary silane. Cyclohexasilane 1 in the chair conformation has C 2h symmetry, predicting unique 1 H NMR signals for the diastereotopic axial and equatorial silane protons.…”