Synthesis, spectral and thermal characterization of nano-sized, oxo-centered, trinuclear carboxylate-bridged chromium(III) complexes of hydroxycarboxylic acids

Complexes of the type [Cr3O(OOCR∗)3(OOCR)3]+ [R∗ = C6H4OH, (R′); C6H5CH(OH), (R″) or (C6H5)2C(OH), (R′″) and R = C15H31 or C17H35] were synthesized by substitutions of acetate ions from their respective acetato complexes, in toluene under reflux. The characterization of the complexes were carried out by spectral (infrared, electronic, FAB mass and powder XRD) studies, elemental analyses, molar conductance and magnetic susceptibility measurements. Their thermal decompositions have been studied by using dynamic, nonisothermal thermogravimetry (TG) and differential scanning calorimetry (DSC). Infrared spectra suggested bidentate and bridging nature of both the carboxylate and hydroxycarboxylate anions along with νasym(Cr3O) vibrations in the complexes. FAB mass spectrometry showed trinuclear nature of the complexes. Molar conductance value of the complexes showed the complexes were 1:1 electrolyte. Magnetic moment values and electronic spectra of these complexes were in support of an octahedral environment around the chromium(III) ion. X-ray diffraction data indicated the nano-sized powder.