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

The scandium complexes of Sc(PMBP)3$H2O (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)3OPMBP(enol)OPMBP(keto). The metal to ligand stoichiometry was found to be 1:3. The crystalline complex melts at 209 8C, followed by degradation at about 310 8C, 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 8C with an exothermic reaction before melting at 217 8C. The IR band observed at approximately, 450 cmK1 is possibly due to the stretching of the Sc–O bond. q 2005 Elsevier B.V. All rights reserved