Thermal studies on metal complexes of 5-nitroso-pyrimidine derivatives

The following Zn(II) complexes of deprotonated 6-amino-5-nitrosouracil (AH), 6-amino-3-methyl-5-nitrosouracil (BH) and 6-amino-1-methyl-5-nitrosouracil (CH) have been prepared and their thermal behaviour studied by TG and DSC techniques: ZnA₂(H₂O)₂, ZnB₂ · 4 H₂O, ZnC₂ · 4 H₂O and ZnC₂(H₂O)₂ · H₂O. The values of the dehydration enthalpy of the complexes are in the 31.3–76.5 kJ mol^?1 H₂O range and, except in the first complex, the dehydration processes take place in several steps. The pyrolysis of the complexes finishes between 540 and 725° C ZnO remaining as residue.     

Square planar 1:1 halide complexes of nickel(II), copper(II), palladium(II) and gold(III) with deprotonated N,N,Z-tridentate hydrazones (Z = S or O) derived from 6-amino-5-formyl-1,3-dimethyluracil

The synthesis and spectroscopic characterization of Ni^II, Cu^II, Pd^II and Au^III complexes containing hydrazones derived from 6-amino-5-formyl-1,3-dimethyluracil and thiosemicarbazide, acetylhydrazine and nicotinic acid is reported. In all cases, the complexes appear to be monomeric and square planar, with three positions occupied by the N,N,Z-tridentate (Z = S or O) ligand, making two five- and six-membered chelate rings and the fourth position occupied by halide.     

A cobalt(II) complex with the N,N,O-tridentate ligand 6-amino-5-formyl-1,3-dimethyluracilato-benzoyl-hydrazone

The crystal structure of bis-(6-amino-5-formyl-1,3-dimethyluracilato benzoylhydrazone)cobalt(II) dimethylformamide solvate is described. This compound crystallizes in the triclinic system, space group P1¯, Z = 2 with a = 9.7368(8), b = 12.346(1), c = 17.184(1) Å, = 78.372(6), = 74.585(6), = 71.113(5)°, and V = 1869.0(3) ų. The coordination polyhedron around the metal ion displays a slightly flattened M(NNO)₂ octahedral shape. Both ligands bind in a trident fashion through the benzoylic oxygen atom, the hydrazone nitrogen atom closer to the uracil ring, and the deprotonated nitrogen atom of the amino group. The two ligands exhibit quite different conformations: one of them is almost planar, whereas the other is severely twisted.