Investigation on the Lanthanoid Chelates of 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone: an examination of the phenomenon of hypersensitivity

Abstract

1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone (Hpmbp) form complexes with lanthanoids of the type Ln(pmbp)₃ · nH₂O (n=4 for La-Sm, and n=1 for Eu-Yb and Y), Ln(pmbp)₃ · 2pyridine·2H₂O, Ln(pmbp)₃ · (2,2'-bipyridine/1,10-phenanthroline)·C₂H₅OH, NH₄[Ln(pmbp)₄]·C₂H₅OH and Q⁺[Ln(pmbp)₄]·C₂H₅OH, where Q⁺ is the quaternary ammonium cation of piperidine, pyrrolidine or morpholine. These compounds have been characterized from physicochemical studies. The electronic spectra of the Nd(III) complexes have been studied in detail to investigate the phenomenon of hypersensitivity with respect to the coordination environment and solvent medium. In these compounds solvent does not play a significant role to cause variation in hypersensitivity. The oscillator strengths of the hypersensitive transition in these compounds show the following trend: Q⁺[Nd(pmbp)₄]>Nd(pmbp)₃·phen>Nd(pmbp)₃·bpy>Nd(pmbp)₃·2py·2H₂>O>Nd(pmbp)₃>·2H₂O. In the Pr(III) complexes the band due to ³H₄→¹D₂ transition has been found to be hypersensitive, and the gradation of intensity due to this band follows almost the same trend as in the corresponding Nd(III) complexes.