Platinum Complexes with Chelating Acyclic Aminocarbene Ligands Work as Catalysts for Hydrosilylation of Alkynes.

This work describes the preparation of a series of platinum-aminocarbene complexes [PtCl{C(N=C (CRRRRCON ))=N(H)R}(CNR)] (-, 65-75% isolated yield) via the reaction of -[PtCl(CNR)] (R = Cy , -Bu , Xyl , 2-Cl-6-MeCH ) with 3-iminoisoindolin-1-ones HN=C (CRRRRCON H) (R-R = H ; R = Me, R, R, R = H ; R, R = Cl, R, R = H ). New complexes - were characterized by elemental analyses (C, H, N), ESI-MS, Fourier transform infrared spectroscopy (FT-IR), one-dimensional (H, C{H}), and two-dimensional (H,H correlation spectroscopy (COSY), H,C heteronuclear multiple quantum correlation (HMQC)/H,C heteronuclear single quantum coherence (HSQC), H,C heteronuclear multiple bond correlation (HMBC)) NMR spectroscopy, and authenticity of known species - was confirmed by FT-IR and H and C{H} NMR. Complexes - were assessed as catalysts for hydrosilylation of terminal alkynes with hydrosilanes to give vinyl silanes, and complex [PtCl{C(N=C (CH(5-Me)CON ))=N(H)(2-Cl-6-MeCH)}{CN(2-Cl-6-MeCH)}] () showed the highest catalytic activity. The catalytic system proposed operates at 80-100 °C for 4-6 h in toluene and with catalyst loading of 0.1 mol %, enabling the reaction of a number of terminal alkynes (PhC≡CH, -BuC≡CH, and 4-(-Bu)CHC≡CH) with hydrosilanes (EtSiH, PrSiH, -PrSiH, and PhMeSiH). Target vinyl silanes were prepared in 48-95% yields (as a mixture of α/β isomers) and with maximum turnover number of 8.4 × 10. Hydrosilylation of internal alkynes (PhC≡CPh, Me(CH)C≡C(CH)Me, and PhC≡CMe) with hydrosilanes (EtSiH, PhMeSiH) led to the corresponding trisubstituted silylated alkenes in 86-94% yields. Initial observations on the mechanism of the catalytic action of platinum-ADC catalysts - suggested a molecular catalytic cycle.