Structural chemistry and thermal properties of some pyrimidine complexes

Abstract

A few complexes of Fe(III), Co(II), Ni (II) and Cu(II) with uracil, 6-amino uracil , and those with substituted phenylazo-6-amino uracils containing <i style="mso-bidi-font-style:normal">o</i>-methyl, <i style="mso-bidi-font-style: normal">p</i>-carboxy and <i style="mso-bidi-font-style:normal">o</i>-carboxy substituents and 5,5'-diethyl barbituric acid sodium salt have been synthesized and characterized by elemental analysis, magnetic moment and spectral measurements (IR, Uv-vis, ESR). The IR spectra show that uracil exists in keto- enol tautomerism but 6-amino uracil possesses the keto amino-imine structure with some enol form. The iron complexes are with O<i style="mso-bidi-font-style: normal">_h</i> geometry, while the cobalt complexes are with different geometries (square planar and O<i style="mso-bidi-font-style:normal">_h<span style="mso-bidi-font-style:italic">). </span></i>The square planar copper complexes exist in ligand bridged structures. The nickel complexes are of tetrahedral configuration. In general, the azo group is involved in the structural chemistry of the azo complexes. The coordination bond length has been calculated. The thermal properties (TG and DTA) of the compounds and their complexes are measured and discussed and also the thermodynamic parameters are evaluated.