The preparation and i.r. and n.m.r. spectra of the series of complexes cis-[PtX₂(RNC)(PR¹₃)](X = Cl, Br, or I; RNC = MeNC, EtNC, PhNC, or p-MeC₆H₄NC and PR¹₃= PEt₃, PEt₂Ph, or PMe₂Ph) are described. These complexes react with alcohols or primary amines under mild conditions to give carbene complexes of the type cis-[PtCl₂{C(Q)NHR}(PR¹₃)](Q = OMe, OEt, or OPrⁱ, NHPh, NHMe, NHEt, or NHBu^s and R = Ph or Me). The i.r. spectra and structure of these complexes are discussed. The isonitrile complexes give hydrocarbons on reduction which must originate from the isocyanide carbon atom. No other products of reduction could be characterised.