Thermonanalytical investigations of monochlorobis (2,4-pentanedionato) vanadium(IV) aryloxides

The thermal decomposition of the complexes [VCl (acac)(2)(OAr)] (where acac =2,4-pentanedionato anion; OAr=-OC6H4O-M-4, OC6H4OBut-4) has been studied u sing non- isothermal techniques (DTA and TG). The TGA indicate that the sub stitution of chlorine in VCl2(acac)(2) with aryloxide ligands results in an increase in the initial temperature of decomposition (IDT) of the new comp lexes. The role of the substituent at the aryloxide ring on the thermal sta bility of the complexes is depicted and hence described. The ultimate decom position product in all the complexes has been identified as V2O5. The kine tic and thermodynamic parameters namely, the energy of activation E, the fr equency factor A, entropy of activation S and specific reaction rate consta nt k(r) etc. have been rationalized in relation to the bonding aspect of th e aryloxide ligands.