Thermoanalytical investigation of magnesium(II) complexes with nicotinamide as bio-active ligand

The stoichiometry of thermal decomposition was studied for the following Mg (II) nicotinamide (NA) complexes: Mg(Ac)(2)(NA)(5). 2H(2)O (I), Mg(ClAc)(2) (NA)(6). 6H(2)O (II), Mg(Cl2Ac)(2)(NA)(6). 5H(2)O (III) and Mg(Cl3Ac)(2)(NA )(6). 2H(2)O (IV), where Ac=CH3COO-, ClAc=ClCH2COO-, Cl2Ac= Cl2CHCOO- and C l3Ac=Cl3CCOO-. Heating the compounds results first in the release of water molecules. The NA molecules are released in one step (complexes II and III) or in two steps (complexes I and IV). The compositions of the complexes, t he solid-state intermediates and the products of thermolysis were identifie d by means of elemental analysis and complexometric titration. The results reveal that MgO is left as residue at the end of thermal degradation of com pounds I-IV. NA is coordinated to Mg(II) through the nitrogen atom of the h eterocyclic ring. The IR data indicate unidentate coordination of the carbo xylate ions to the Mg(II) in complexes I-IV.