Syntheses of mono- and dinuclear silylplatinum complexes bearing a diphosphino ligand via stepwise bond activation of unsymmetric disilanes

Abstract

Zero-valence platinum complex [Pt(dppe)(eta(2)-C(2)H(4))] (1, dppe = 1,2-bis(diphenylphosphino)ethane) treated with disilanes HR(1)R(2)SiSiMe(3) (a, R(1) = R(2) = Me; b, R(1) = R(2) = Ph; c, R(1) = H, R(2) = Ph) afforded the corresponding disilanylplatinum hydrides [Pt(dppe)(H)(SiR(1)R(2)SiMe(3))] (2a-c) by oxidative addition of the Si-H bond to the platinum center. The 1,2-silyl migration in 2a,b led to the formation of bis(silyl)platinum complexes [Pt(dppe)(SiHR(1)R(2))(SiMe(3))] (3a,b) with a first-order rate constant of 7.2(2) x 10(-4) s(-1) at 25 degrees C for 2a and 3.86(4) x 10(-4) s(-1) at 40 degrees C for 2b, whereas 2c with R(1) = H followed by the transient generation of 3c dimerized rapidly to give the bis(mu-silylene)diplatinum complex [Pt(dppe)(mu-SiHPh)](2) (4c) in a mixture of cis/trans isomers. Heating of the toluene solution of 3b at 100 degrees C resulted in a similar dimerization to 4b. In addition, a trinuclear platinum complex [Pt(3)(dppe)(3)(mu(3)-SiPh)(2)] (5) with a trigonal bipyramidal Pt(3)Si(2) core arose from the reaction of 4c with 1 at 60 degrees C in toluene. Unsymmetric disilanes therefore accomplished the syntheses of various monomeric and dimeric platinum complexes via 1,2-hydrogen and silyl migration to the platinum center.