The divalent metal complexes of Be, Mn, Co, Ni, Cu, Zn, Hg, Pb, and Mg with 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5, (HPMTFP) have been prepared for the first time. The metal complexes were characterized by means of elemental analyses, conductivity measurements, proton NMR and i.r. spectroscopy, and it is concluded that the ligand, HPMTFP, reacts as a bidentate enol forming neutral metal chelates. The i.r. spectra were measured between 4000-200 cm−1 and assignments are proposed for the observed frequencies. Replacement of the methyl group by CF3 group in the acetyl moiety of 1-phenyl-3-methyl-4-acetyl-pyrazolone-5, HPMAP, is found to increase the CO and CC bond strengths and decrease that of the MO bond. The magnitudes of MO stretching frequencies show good agreement with the Irving—Williams stability order Cu > Ni > Co > Mn > Zn.
Spectrochimica Acta Part A Molecular Spectroscopy 12/1981; 37(11):951-955. DOI:10.1016/0584-8539(81)80021-9