Synthesis and cyclization reactions of platinum(II)-coordinated arsonium-substituted phenyl isocyanides, o-(I−R3As+–CH2)C6H4NC

The arsonium-substituted isocyanides, o-(I−+R3AsCH2)C6H4NC (AsR3=AsPh3, L1; AsMePh2, L2; AsMe2Ph, L3), were prepared by reaction of o-(chloromethyl)phenyl isocyanide, o-(CH2Cl)C6H4NC, with a slight molar stoichiometric amount of the arsine in the presence of a 3-fold excess of NaI in acetone at room temperature. The isocyanides L1–L3 coordinate to some Pt(II) complexes such as trans-[PtX{o-(I−+R3AsCH2)C6H4NC}(PPh3)2] [BF4] (AsR3=AsPh3, 1; AsMePh2, 2; AsMe2Ph, 3; X=Cl, I) and [PtX{o-(I−+R3AsCH2)C6H4NC}(Ph2PCHCHPPh2)] [BF4] (AsR3=AsMePh2, 4; X=Cl, I). Complexes 2–4 are converted in CH2Cl2 at room temperature in the presence of NEt3 to the corresponding indolidin-2-ylidene derivatives trans-[PtX{(AsR3)}(PPh3)2]BF4] (AsR3=AsPh3, 5; AsMePh2, 6; AsMe2Ph, 7) and [PtX{(AsMePh2)}(Ph2PCHCHPPh2)][BF4] (8).