Si-H and Si-C bond activation of a triorganosilane promoted by [RhCl{P(i-Pr)(3)}(2)]. Synthesis and structure of a dinuclear Rh(IV) complex with mu-silylene ligands

[RhCIL(2)] (L = P(i-Pr)(3)) reacts with tris(2-phenylethyl)silane in pentane to give a dinuclear Rh(IV) complex, [LRh-(H)(2){mu-Si(CH(2)CH(2)Ph)(2)}Rh-2(H)(2)L] (1), and several organic products including ethylbenzene, chloro{tris(2-phenylethyl)}silane, and tetrakis(2-phenylethyl)silane. Results of X-ray crystallography and NMR study of 1 indicate a symmetrical molecular structure containing two Rh(IV) centers which are bonded to each other through two bridging silylene ligands. [1, triclinic, space group P (1) over bar with a = 12.886(4), b = 13.217(3), c = 10.388(3) Angstrom, alpha = 104.78(2), beta = 106.50(2), gamma = 61.70(2)degrees, V = 1478 Angstrom(3), Z = 1, R = 0.073, R(w) = 0.081 for 3930 reflections with I > 3 sigma(I) and 289 variables]. The initial reaction products contain mononuclear Rh(III) complexes, [RhCl(H)(2)L(2)] (2) and [RhCl(H) {Si(CH(2)CH(2)Ph)3}L(2)] (3), the latter of which is turned into 1 on further stirring. Reactions of tribenzylsilane and of tris(p-methylbenzyl)silane with [RhClL(2)] cause immediate separation of [RhL(R(3)Si)H(mu-Cl)(2)RhH(SiR(3))L] (4: R = CH(2)Ph, 5: R = CH(2)C(6)H(4)Me-p). X-Ray crystallography of 4 has revealed the structure containing two Rh(III) centers with distorted trigonal bipyramidal coordination [4, monoclinic, space group P2(1)/n with a = 11.513(3), b = 28.227(9), c = 20.883(5) Angstrom, beta = 94.14(2)degrees, V = 6769 Angstrom(3), Z = 4, R = 0.071, R(w) = 0.066 for 4249 reflections with I > 3 sigma(I) and 637 variables]. A prolonged reaction of tribenzyl-silane leads to formation of chlorotribenzylsilane.