Metal Chelates of Hydrazo-?-Diketone Ligands. Chelating Tendencies of 2-Carboxyphenylhydrazodibenzoylmethane and 2-Carboxyphenylhydrazothienoyltrifluoroacetone

Abstract

The acid-base properties of 2-carboxyphenylhydrazodiebnzoyl methane (2-CPHDBM) and 2-carboxylphenylhydrazothienoyltrifluoroacetone (2-CPHTTA) and their equilibria with transition and lanthanide ions in 75% (v/v) dioxanwater solvent at 30ºC have been investigated by pH titrimetry. The application of the theoretical equation derived by Irving and Rossotti indicates that the coordination modes of 2-CPHDBM and 2-CPHTTA toward the transition and lanthanide ions are the same. The stability constants for transition and lanthanide ion complexes with respect to the organic ligands follow the order: 2-CPHTTA > 2-CPHDBM.