Synthesis and structural characterization of Zn(II), Ag(I) and Pd(II) complexes with 2,4-diamino-5-nitroso-6-oxopyrimidine.: Crystal and molecular structure of [ZnCl2(L)(H2O)] and [Ag(NO3)(L)2]

Three complexes of formula [ZnCl2(L)(H2O)], [Ag(NO3)(L)(2)] and [PdCl2(L)]. 2H(2)O have been obtained by reacting the ligand 2,4-diamino-5-nitroso-6-oxo-pyrimidine with the corresponding metal salt. The complexes have been characterized by thermal and spectroscopic techniques and, for the two former, by single crystal X-ray diffraction. [ZnCl2(L)(H2O)]: C5H9N5O3Cl2Zn, a=9.197(5), b=11.663(6), c=10.166(7)Angstrom, beta=90.66(3), monoclinic, P2(1)/n, Z=4. [Ag(NO3)(L)(2)]: C10H14N11O7Ag, a=15.920(5), b=7.395(5), c= 14.408(5) Angstrom, beta = 97.678(5), monoclinic, C2/c, Z=4. In all of them the ligand coordinates in a neutral bidentate fashion through the exocyclic nitroso and oxo groups, in the two former complexes through the N(5)/O(6) atoms whereas in the latter the donor atoms are the O(5)/O(6). These coordination modes are connected with the fact that the ligand is able to adopt two conformations depending on the intramolecular N(4)H ... O(5) hydrogen bond. (C) 1999 Elsevier Science Ltd. All rights reserved.