Thermal and spectroscopic studies of scandium complex of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone

The scandium complexes of Sc(PMBP)(3)(H2O)-H-. (non-crystal) and Sc(PMBP)(3) (crystal) with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) were prepared and characterized by thermal analysis, IR, NMR and MS spectroscopies. The crystal structure of the complex, obtained by X-ray analysis, indicates that PMBP is a bidentate ligand in the complex and that the Sc atom is six-coordinate and is in a meridional octahedral environment. The order of the ring current effect on the pyrazolone ring is Sc(PMBP)3 > PMBP(enol) > PMBP(keto). The metal to ligand stoichiometry was found to be 1:3. The crystalline complex melts at 209 degrees C, followed by degradation at about 3 10 degrees C, with the beginning of decomposition. The enthalpy of melting was found to be 61 kJ/mol. On the other hand, the non-crystalline complex was found to change into a crystalline complex at 176 degrees C with an exothermic reaction before melting at 217 degrees C. The IR band observed at approximately, 450 cm(-1) is possibly due to the stretching of the Sc-O bond. (c) 2005 Elsevier B.V. All rights reserved.