| Abstract |
This work describes the preparation of a series of platinum-aminocarbene complexes [PtCl\(C) under bar (N = C-a((C6RRRRCO)-R-2-R-3-R-4-C-5 (N) under bar (b))) = N(H)R-1\(CNR1)](a-b) (8-19, 65-75\% isolated yield) via the reaction of cis-[PtCl2(CNR1)(2)] (R-1 = Cy 1, t-Bu 2, Xyl 3, 2-Cl-6-MeC6 H-3 4) with 3-iminoisoindolin-1-ones HN = C-a((C6RRRRCONH)-R-2-R-3-R-4-C-5-H-b) (R-2-R-5 = H 5; R-3 = Me, R-2, R-4, R-5 = H 6; R-3, R-4 = Cl, R-2, R-5 = H 7). New complexes 17-19 were characterized by elemental analyses (C, H, N), ESI+-MS, Fourier transform infrared spectroscopy (FT-IR), one-dimensional (H-1, C-13\H-1\), and two-dimensional (H-1, H-1 correlation spectroscopy (COSY), H-1, C-13 heteronuclear multiple quantum correlation (HMQC)/H-1, C-13 heteronuclear single quantum coherence (HSQC), H-1, C-13 heteronuclear multiple bond correlation (HMBC)) NMR spectroscopy, and authenticity of known species 8-16 was confirmed by FT-IR and H-1 and C-13\H-1\ NMR. Complexes 8-19 were assessed as catalysts for hydrosilylation of terminal alkynes with hydrosilanes to give vinyl silanes, and complex [PtCl\(C) under bar (N = C-a(C6H3(5-Me)CO (N) under bar (b))) = N(H)(2-Cl-6-MeC6H3)\\CN(2-Cl-6-MeC6H3)\](a-b) (18) showed the highest catalytic activity. The catalytic system proposed operates at 80-100 degrees 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 equivalent to CH, t-BuC equivalent to CH, and 4-(t-Bu)C6H4C equivalent to CH) with hydrosilanes (Et3SiH, Pr3SiH, i-Pr3SiH, and PhMe2SiH). Target vinyl silanes were prepared in 48-95\% yields (as a mixture of alpha/beta isomers) and with maximum turnover number of 8.4 x 10(3). Hydrosilylation of internal alkynes (PhC equivalent to CPh, Me(CH2)(2)C equivalent to C(CH2)(2)Me, and PhC equivalent to CMe) with hydrosilanes (Et3SiH, PhMe2SiH) led to the corresponding trisubstituted silylated alkenes in 86-94\% yields. Initial observations on the mechanism of the catalytic action of platinum-ADC catalysts 8-19 suggested a molecular catalytic cycle. |
