Facile cyanamide-ammonia coupling mediated by cis- and trans-[PtIIL2] centers and giving metal-bound guanidines.

Diffusion of ammonia into CH(2)Cl(2) solutions of the dialkylcyanamide complexes cis- or trans-[PtCl(2)(RCN)(2)] (R = NMe(2), NEt(2), NC(5)H(10)) at 20-25 degrees C leads to metal-mediated cyanamide-ammonia coupling to furnish, depending on reaction time, one or another type of novel bisguanidine compound, i.e. the molecular cis- or trans-[PtCl(2){NH=C(NH(2))R}(2)] (cis- and trans-) and the cationic cis- or trans-[Pt(NH(3))(2){NH=C(NH(2))R}(2)](Cl)(2) (cis- and trans-) complexes. Compounds cis- or trans- were converted to cis- or trans-, accordingly, upon prolonged treatment with NH(3) in CH(2)Cl(2). The ammination of the relevant nitrile complexes cis- or trans-[PtCl(2)(RCN)(2)] (R = Et, CH(2)Ph, Ph) in CH(2)Cl(2) solutions affords only the cationic compounds cis- or trans-[Pt(NH(3))(2){NH=C(NH(2))R}(2)](Cl)(2) (cis- and trans-). The formulation of was supported by satisfactory C, H and N elemental analyses, agreeable ESI(+)-MS (or FAB(+)-MS), IR, (1)H and (13)C NMR spectroscopies. The structures of trans-, trans-, cis-, trans-, cis-, and cis- were determined by single-crystal X-ray diffraction disclosing structural features and showing that the ammination gives ligated guanidines and amidines in the E- and Z-forms, respectively, where both correspond to the trans-addition of NH(3) to the nitrile species.