The First Metal Complexes of 4,6-diamino-1-hydro-5-hydroxy-pyrimidine-2-thione: Preparation, Physical and Spectroscopic Studies, and Preliminary Antimicrobial Properties

The new complexes [M(2)O(5)L(2)(H(2)O)(2)] . H(2)O (M = Mo, 1; M = W, 2), [RuL(2)(H(2)O)(2)] . H(2)O (3), [ML(3)] . xH(2)O (M = Rh, x = 2, 4; M = Ir, x = 1, 5), [RhL(2)(PPh(3))(2)](ClO(4)) . 2H(2)O (6), [PdL(2)] . 2H(2)O (7), [PdL(phen)]Cl . H(2)O (8), [Re OL(2)(PPh(3))]Cl (9) and [UO(2)L(2)] (10) are reported, where LH is 4,6-diamino-1-hydro-5-hydroxy-pyrimidine-2-thione. The complexes were characterized by elemental analyses, physical techniques (molar conductivity, room-temperature magnetic susceptibility), and spectroscopic (IR, Raman, UV/VIS/ligand field, NMR, mass) methods. The ligand L(-) is in its thione form and behaves as a bidentate chelate with the deprotonated (hydroxyl) oxygen and the nitrogen of one amino group as donor atoms. Oxobridged dinuclear (1, 2) and various mononuclear (3-10) structures are assigned for the complexes in the solid state. The metal ion coordination geometries are octahedral (1-6, 9, 10) or square planar (7, 8). The free ligand LH and complexes 1, 4, 7, and 8 were assayed in vitro for antimicrobial activity against two bacterial and two fungal cultures.