Syntheses and spectrothermal studies of triethanolamine complexes of Co(II), Ni(II), Cu(II) and Cd(II) squarates

Abstract

The triethanolamine complexes, [M(tea)(2)]sq center dot nH(2)O, (n=2 for Co(II), n=0 for Ni(II), Cu(II) and n=1 for Cd(II), tea=triethanolamine, sq(2-)=squarate), have been synthesized and characterized by elemental analyses, magnetic susceptibility and conductivity measurements, UV-Vis and IR spectra, and thermal analyses techniques (TG, DTG and DTA). The Co(II), Ni(II) and Cu(II) complexes possess octahedral geometry, while the Cd(II) complex is monocapped trigonal prismatic geometry. Dianionic squarate behaves as a counter ion in the complexes. The thermal decomposition of these complexes takes place in three stages: (i) dehydration, (ii) release of the tea ligands and (iii) burning of organic residue. On the basis of the first DTG(max) of the decomposition, the thermal stability of the anhydrous complexes follows the order: Ni(II), 289 degrees C > Co(II), 230 degrees C > Cu(II), 226 degrees C > Cu(II), 170 degrees C in static air atmosphere. The final decomposition products - the respective metal oxides - were identified by FTIR spectroscopy.