Platinum(II) and Palladium(II) Complexes withN-Aminoguanidine

N-Aminoguanidine (Amgu) was examined for its behaviour as a ligand for platinum(II) and palladium(II). Protonated AmguH(+) can coordinate platinum as a monodentate ligand bound via the N4 amino group. Deprotonated, electrically neutral Amgu forms chelate complexes with both Pt-II and Pd-II; in these complexes Amgu is coordinated to the metal by the N4 amino group and the deprotonated N1 imino group, forming a five-membered ring. K[PtCl3(dmso)] reacted with Amgu center dot HCl to yield a chelate complex with N1 bound trans to S, suggesting that an exchange between the N1 and N4 binding sites followed the primary nucleophilic attack of N4 on platinum. Whereas reactions between K2PdCl4 and Amgu center dot HCl were rapid and straightforward, K2PtCl4 was easily reduced to metallic platinum by Amgu center dot HCl, especially in stoichiometric conditions. Solution NMR and X-ray crystallographic characterization is presented for five new complexes: trans-[PtCl2(AmguH-N4)(2)]Cl-2 center dot 2(1/2)H(2)O (3), trans-[Pt(Amgu-N1,N4)(2)](NO3)(2) (4), [PtCl(Amgu-N1,N4)(dmso)]Cl center dot 2H(2)O (5), [PdCl2(AmguH-N1,N4)] (6), and trans-[Pd(Amgu-N1, N4)(2)]- Cl-2 (7). ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).