MONO-DENTATE, DI-DENTATE AND TRI-DENTATE BINDING MODES OF A SUBSTITUTED ISOCYTOSINE DERIVATIVE IN COMPLEXES OF PALLADIUM AND ZINC

The crystal and molecular structures of three metal complexes of the p yrimidine derivative, droxyethyl)-(2-aminoethyl-N-2)-5-methylisocytosi ne reveal that, as a ligand, this heterocyclic base exhibited a divers e range of co-ordination modes. With zinc(II), monodentate co-ordinati on via the carbonyl oxygen of the pyrimidine base was observed. In the case of palladium(rr), both a didentate mode, via endo- and exo-cycli c nitrogen donors, and a tridentate mode, involving exocyclic nitrogen s and the alcohol oxygen donors, was observed. In the latter case the pyrimidine exists in the rare iminooxo tautomeric form.