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

摘要

Zero-valence platinum complex [Pt(dppe)(η~2-C _2H_4)] (1, dppe = 1,2-bis(diphenylphosphino)ethane) treated with disilanes HR~1R~2SiSiMe_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~1R~2SiMe_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 ~1R~2)(SiMe_3)] (3a,b) with a first-order rate constant of 7.2(2) × 10~(-4) s~(-1) at 25°C for 2a and 3.86(4) × 10~(-4) s~(-1) at 40°C for 2b, whereas 2c with R~1 = H followed by the transient generation of 3c dimerized rapidly to give the bis(μ-silylene)diplatinum complex [Pt(dppe)(μ-SiHPh)] _2 (4c) in a mixture of cis/trans isomers. Heating of the toluene solution of 3b at 100°C resulted in a similar dimerization to 4b. In addition, a trinuclear platinum complex [Pt_3(dppe) _3(μ_3-SiPh)_2] (5) with a trigonal bipyramidal Pt_3Si_2 core arose from the reaction of 4c with 1 at 60°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.