ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Synthesis, spectral and electrochemical study of coordination molecules Cu₄OX₆L₄: 3-cyanopyridine Cu₄OBr_nCl_(6−n)(3-CNpy)₄ complexes

Gregor Ondrejovič, Adela Kotočová, Marian Koman, and Peter Segľa

Institute of Inorganic Chemistry, Technology and Materials, Faculty of Chemical and Food Technology, Slovak University of Technology, SK-812 37 Bratislava, Slovak Republic

E-mail: gregor.ondrejovic@stuba.sk

Received: 4 September 2009  Revised: 19 November 2009  Accepted: 30 November 2009

Abstract: Seven new 3-cyanopyridine Cu₄OBr _n Cl_(6−n)(3-CNpy)₄ (n = 0–6) complexes were prepared and studied by infrared spectra, electronic spectra, and cyclic voltammetry. Infrared spectra revealed a distortion of the tetrahedral Cu₄O core to C _2ν or C _3ν symmetries and a donor-acceptor vibrational coupling with the in-plane pyridine ring bending within the O-Cu-(pyridine ring)CN system involving the π-back bonding between Cu(II) atoms and 3-CNpy ligands. Bands of the electronic spectra and half-wave potentials of the complexes are consistent with the weak donor and strong acceptor behaviour of the 3-CNpy ligands. The results were compared with analogous complexes of pyridine, 3-substituted and 4-substituted pyridine ligands.

Keywords: copper(II) 3-cyanopyridine complexes - donor-acceptor vibrational coupling - electronic spectra - electrochemistry -  π-back bonding

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-010-0016-8

Chemical Papers 64 (3) 339–345 (2010)