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-o xo-pyrimidine with the corresponding metal salt. The complexes have been ch aracterized 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 li gand coordinates in a neutral bidentate fashion through the exocyclic nitro so 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 con formations depending on the intramolecular N(4)H ... O(5) hydrogen bond. (C ) 1999 Elsevier Science Ltd. All rights reserved.