Preparation and structures of hydrido (organosilyl) arenethiolatorhodium(III) complexes with PMe3 ligands. Irreversible and reversible oxidative addition of an SiH bond to thiolatorhodium (I) complexes

Reactions of Hydrosilanes with Transition Metal Complexes and Characterization of the Products

“…Examples include 2-61, 109 2-62, 110 3-192 to 3-194 109 (X ) SAr), and 3-185, 242 3-186, 243 3-189a 243 (X ) Cl). The initially formed 5-coordinate complex, 3-201, 249 from ( i Pr 3 P) 2 RhCl and HSiR 3 (R ) CH 2 CH 2 Ph), was detected spectroscopically but reacted further to form a Rh dimer with bridging silylene units.…”

Intermolecular Transfer of Triarylsilane from RhCl(H)(SiAr3)[P(i-Pr)3]2 to a Platinum(0) Complex, Giving cis-PtH(SiAr3)(PEt3)2 (Ar = C6H5, C6H4F-p, C6H4Cl-p)

“…Recently we observed the reaction of Rh(SPh)(PMe 3 ) 3 with HSiAr 3 to give an equilibrated mixture of Rh(SPh)-(PMe 3 ) 3 and Rh(H)(SiAr 3 )(SPh)(PMe 3 ) 3 . 6 Deuterium labeling experiments of the reaction of RhCl(H)(SiHAr 2 )-(PMe 3 ) 3 with diarylsilane have revealed exchange of the organosilane and silyl and hydrido ligands through rapid and reversible reductive elimination and oxidative addition, shown in Scheme 1. 7 Another conceptually possible productive reductiveelimination and oxidative-addition process of the Si-H bond could be achieved by a reaction of a hydridosilylmetal complex with a complex having a different metal center to cause transfer of both hydrido and silyl groups from one metal center to the other, as depicted in Scheme 2.…”

“…Oxidative addition of an Si−H bond to low-valent transition-metal complexes, including Pt(0) complexes, provides a general synthetic route to silyl complexes of these metals and is involved in transition-metal-complex-catalyzed hydrosilation of alkenes and dehydrocoupling of organosilanes as a crucial step. , The oxidative addition of organosilanes and their reductive elimination from silyl(hydrido)metal complexes are generally accepted to be reversible and to involve silane-coordinated metal complexes as the common intermediate. − However, direct observation of reversible oxidative addition and reductive elimination of the Si−H bond is rare, probably due to the high stability of M−Si bond. Recently we observed the reaction of Rh(SPh)(PMe 3 ) 3 with HSiAr 3 to give an equilibrated mixture of Rh(SPh)(PMe 3 ) 3 and Rh(H)(SiAr 3 )(SPh)(PMe 3 ) 3 …”

Isomers of Chloro(triarylsilyl)hydridorhodium(III) Complexes, mer-RhCl(H)(SiAr3)(PMe3)3. Relevance of Their Structures to Reductive Elimination of ClSiAr3

“…Table summarizes selected bond distances and angles of the molecule. The Rh−Si bond distance (2.346(2) Å) is shorter than that found in the structurally analogous complexes mer -Rh(SAr)H(SiPh 3 )(PMe 3 ) 3 (2.38 Å), indicating a smaller trans influence of the chloro ligand.

1 ORTEP drawing of mer -RhCl(H)(SiPh 3 )(PMe 3 ) 3 ( 1 ) at the 30% ellipsoidal level.

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“…The 31 P{ 1 H} NMR spectrum contains a doublet of doublets and a doublet of triplets in ca. 2:1 peak area ratio similar to mer -RhCl(H)(SiHAr 2 )(PMe 3 ) 3 and mer -Rh(SAr)(H)(SiAr 3 )(PMe 3 ) 3 . , The 1 H NMR spectrum of 1 at 25 °C in toluene- d 8 shows a SiH hydrogen peak (δ 5.70) whose relative intensity decreases on cooling the solution and is almost negligible at −70 °C. The temperature-dependent NMR spectra suggest that complex 1 is in a reversible equilibrium with a mixture of HSiPh 3 and Rh(I) complexes formed through reductive elimination of HSiPh 3 .…”