Synthesis, ESR and TGA Studies of Mononuclear and Single‐Bridged Binuclear Complexes of Copper(II) Involving Heterocyclic Nitrogen Bases and Heterocyclic β‐Diketones

Abstract

Binuclear complexes of copper(II) have been synthesised by the reaction of aromatic diamines with mixed‐ligand (mononuclear) complexes. The mixed‐ligand complexes consist of the ligands 2,2′‐dipyridyl or 1,10‐phenanthroline and 1‐phenyl‐3‐methyl‐4‐benzoyl‐2‐pyrazolin‐5‐one (HPmBzP) or 1‐phenyl‐3‐methyl‐4‐acetyl‐2‐pyrazolin‐5‐one (HpmAcP). On reaction with 2,6‐diaminopyridine (DIPy) or m‐phenylenediamine (m‐PhDA) condensation occurs with the R–C=O groups of two complexed molecules, thus bridging the two united ligand copper(II) complexes. Electronic, infrared and ESR spectra, the magnetochemistry, thermogravimetric and conductometric studies of these complexes are described. Since having one bridge between two paramagnetic centres, these complexes are expected to be better for a comparative study of long‐range antiferromagnetic interactions. ESR spectral data in solution indicate weak antiferromagnetic interaction resulting from the electron delocalization to the ligand system. The energy of the activation of each step of the thermal decomposition of the complexes has been calculated and the thermal stability of these complexes are presented.

Keywords:

• Mononuclear
• Binuclear
• Cu(II) complexes
• Single‐bridge binuclear complexes
• Heterocyclic β‐diketones

Acknowledgments

The authors are thankful to the Regional Sophisticated Instrumentation Center, Indian Institute of Technology, Mumbai, for ESR facilities.