Synthesis and characterization of tertiaryphosphinecobalt(III) Schiff base complexes and their thermodynamic study with organic bases in different solvents

Abstract

The [Co(acacen)(PMe 2Ph)]ClO 4 · H 2O (acacen=bis(acetylacetone)ethylene diimine) was synthesized and characterized. The equilibrium constants and the thermodynamic parameters were measured spectrophotometrically for 1:1 adduct formation of [Co(acacen)L]ClO 4 · H 2O, where (L=PBu 3, PMe 2Ph) as acceptors with H 2NR (R= n-propyl, n-butyl, sec-butyl) as donors, in ethanol and butanol solvents in constant ionic strength ( I=0.01 M NaClO 4) and at various temperatures T=(288 to 308) K. The trend of the reactivity of five-coordinate cobalt(III) Schiff base complexes toward a given amine donor according to the axial ligand is as follow: PMe 2Ph > PBu 3. Also the trend of the reactivity of the donors (amines) toward a given cobalt(III) Schiff base complex is as follow: n-propylamine > n-butylamine > sec-butylamine. The trend of the reactivity of a given cobalt(III) Schiff base complexes toward a given amine donor according to the solvent is as follow: butanol > ethanol.