Synthesis and structural characterization of Zn(II), Ag(I) and Pd(II) complexes with 2,4-diamino-5-nitroso-6-oxopyrimidine. Crystal and molecular structrue of [ZnCl_2(L)(H_2O)] and [Ag(NO_3)(L)_2]

摘要

Three complexes of formula [ZnCl_2(L)(H_2O)], [Ag(NO_3)(L)_2] and [PdCl_2(L)] centre dot 2H_2O 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, [ZnCl_2(L)(H_2O)]: C_5H_9N_5O_3Cl_2Zn, a = 9.197(5), b = 11.663(6), c = 10.166(7) A, #beta# = 90.66(3), monoclinic, P2_1, Z = 4. [Ag(NO_3)(L)_2]: C_(10)H_(14)N_(11)O_7Ag, a = 15.920(5), b = 7.395(5), c = 14.408(5) A, #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.