Synthesis, crystal structure and thermal decomposition mechanism of a samarium o-chlorobenzoate complex with 1,10-phenanthroline

The title complex [Sm(oClBA)3phen]2 (oClBA= o-chlorobenzoate; phen= 1,10-phenanthroline) was prepared by the reaction of SmCl3·6H2O, o-chlorobenzoic acid and 1,10-phenanthroline. The complex was characterized by single crystal X-ray diffraction, elemental analysis, IR spectra and TG-DTG techniques. The results show that the crystal is triclinic, space group P I with a = 13.157(3) Å, b = 14.139(4) Å, c = 17.397(4) Å, alpha = 83.755(3)º, beta = 84.064(3)º, gamma =73.434(3)º, Z=2, Dc=1.722 Mg/m³, F(000)=1572. The crystal contains two crystallographically distinct Sm(o-ClC6H4COO)3(C12H 8N2) units, forming two types of binuclear molecule. Each Sm3+ is coordinated to two O atoms of one bidentate chelating carboxylate group, five O atoms of two bidentate bridging and two tridentate chelating-bridging carboxylate groups, and two N atoms of one 1,10-phenanthroline molecule to complete a distorted mono-capped square antiprism geometry. Its thermal decomposition mechanism was determined by TG-DTG techniques, and kinetic parameters have been studied on the first-step decomposition of [Sm(oClBA)3phen]2 by means of Kissinger's method and Ozawa-Doyle's method. The lifetime equation at weight-loss of 10% was deduced as lntau= 26.8166+20319.94/T by isothermal thermogravimetric analysis.