Open Journal of Inorganic Chemistry

Mohamed A. El-Sayed ¹, Hoda A. Elwakeil ¹, Ahmed H. Abdel Salam ¹, Hemmat A. Elbadawy ¹

Affiliations
1 Chemistry Department, Alexandria University, Alexandria, EG

Abstract

In this work, novel oxidative coupling complexes, [(Pip)_4nCu₄X₄(CO₃)₂] (n = 1 or 2, X = Cl or Br, Pip = piperidine), are synthesized from the reaction of well characterized Lewis base [(Pip)_4nCu₄X₄O₂] with carbon dioxide as a Lewis acid in CH₂Cl₂. These carbonato-derivatives are isolated as stable solids. They are easily soluble in aprotic solvents as CH₂Cl₂ or phNO₂. Cryoscopic measurements support tetranuclear structure for all of them. Electronic spectra in the near infrared with high molecular absorptivity may be explained for tetranuclear cuban structure to fulfil 3 halo-ligands for each copper centre in [(Pip)_4nCu₄X₄(CO₃)₂]. The EPR spectra for [(Pip)_4nCu₄X₄(CO₃)₂] complexes are axial type of spectra (d_x2-y2 G.S.) suggesting elongated tetragonal distortion for all of them. Cyclic voltammograms for [(Pip)_4nCu₄X₄(CO₃)₂] are irreversible in character. These tetranuclear carbonato complexes show catalytical activity. They initiate the oxidation of 2,6-dimethylphenol (DMP) to 3,3',5,5'-tetramethyl-4,4'-diphenoquinone (DPQ).

Keywords

Complexes, Tetranuclear Cuban, Carbonato Bridge, Copper.

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