Mutual Placement of Isocyanide and Phosphine Ligands in Platinum(II) Complexes [PtHal2L1L2] (Hal = Cl, Br, I; L1,L2 = CNCy, PPh3) Leads to Highly-Efficient Photocatalysts for Hydrosilylation of Alkynes

A series of platinum complexes featuring phosphine and isocyanide ligands [PtX2(PPh3)(CNCy)] (X = Cl, Br, and I) as well as their parent phosphine [PtX2(PPh3)(2)] and isocyanide [PtX2(CNCy)(2)] analogues have been prepared and evaluated as catalysts for the photocatalytic hydrosilylation of alkynes. Under violet light irradiation (lambda(max) = 400 nm), phosphine-isocyanides complexes [PtX2(PPh3)(CNCy)] gave high yields of silylated products (product yield up to 99%, TONs up to 1.98 x 10(3)). The blue light irradiation (lambda(max) = 450 nm) was more suitable for the parent phosphine complexes [PtX2(PPh3)(2)], which showed comparable efficiency (product yield up to 99%, TON up to 1.98 x 10(3)), while isocyanide complexes [PtX2(CNCy)(2)] were not active.