Addition of aliphatic, secondary amines to coordinated isonitriles. N-acyclic carbene (NAC) platinum(II) complexes from trans-[Pt(μ-Cl)Cl(PPh3)

Abstract

Isocyanide ligands RNC (R = 4-(MeO)C6H4-, PhCH2) react smoothly with trans-[Pt(μ-Cl)Cl(PPh3)]2 to afford trans-[PtCl2(PPh3)(CNR)] complexes, which are promptly converted, in solution, to the corresponding cis isomers. The obtained derivatives react with N,N-dialkylamines to afford the corresponding N-acyclic carbene (NAC) addition products. When alicyclic N,N-dialkylamine (Ŕ2NH, Ŕ= ethyl, benzyl) were used, only the expected neutral dichlorocarbene product cis-[PtCl2(PPh3)(Ŕ2NCN(H)R)] were obtained in high yields, while when cyclic amines R′2N^H were used (morpholine, piperidine, pyrrolidine), variable amounts of ionic [PtCl(PPh3)(R′2N^H)(R′2N^ CN(H)R)]Cl were observed, arising from the substitution of a residual chlorido ligand by the used amine. The amount of the ionic derivative observed depends on the amine nucleophilicity.