Synthesis and reactions of cis-sily(boryl)platinum(II) complexes

Article abstract of DOI:10.1021/om020686z

Four kinds of sily(boryl)platinum(II) complexes, 2a-2d, have been prepared by oxidative addition of silylboranes to platinum(0) complexes, in situ generated from Pt(cod)₂ and 2 molar quantity of tertiary phosphine ligands (L) in Et₂O: cis-Pt(SiMe₂Ph)(BX₂)L₂ (X2 = -OCMe₂CMe₂O- (pin), L = PMe₃ (2a), PMe₂Ph (2b), PEt₃ (2c); X₂ = -NMeCH₂CH₂NMe- (dmeda), L = PMe₃ (2d)). Complexes 2a-2c undergo selective insertion of phenylacetylene into the Pt-B bond at room temperature in CD₂Cl₂, giving cis-Pt{C(Ph)=CH(Bpin)}(SiMe₂Ph)L₂ (L = PMe₃ (3a), PMe₂Ph (3c), PEt₃ (3c)), respectively, while 2d is inactive toward insertion. The X-ray structure of 3b has been determined. Kinetic study using 2a indicates the mechanism involving prior dissociation of L, followed by insertion of phenylacetylene into the Pt-B bond. The insertion complexes 3a-3c undergo C-Si reductive elimination to give (Z)-α-silyl-β-borylstyrene. The reactivity decreases in the order 3c ? 3b > 3a.