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

Spectral and Electrochemical Study of Coordination Molecules Cu ₄OX ₆L ₄: Cu ₄ OBrnCl _(6−n) (Pyridine) ₄ Complexes

G. Ondrejovič and A. Kotočová

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

E-mail: gregor.ondrejovic@stuba.sk

Received: 24 February 2004

Abstract: The tetranuclear Cu4OBrnCl(6−n)(py)4 complexes, where py = pyridine and n = 0—6, with trigonal bipyramidal coordination of copper were prepared and their electronic spectra and cyclic voltammograms in nitromethane solutions were measured. The energy, intensity, and half-width of the two overlapped d—d bands were obtained by the Gaussian resolution. The maxima of the high-energy bands assigned to e(dxz, dyz) → a1(dz2 ) transitions are in a linear correlation with the number of bromoligands, n, ˜ν2max(G)/cm−1 = −53.0n + 13420. The maxima of the lowenergy bands assigned to e(dx2−y2, dxy) → a1(dz2) transitions approximate a polynomial correlation ˜ν1max(G)/cm−1 = −7n − 3n2 + 11300. Formal reduction potentials E_1/2 of the complexes varied with the number of bromoligands in the range 457 mV—519 mV. This variation is described by the equation E_1/2(n) = E_1/2(3) − k log [(6 − n)/n], k represents the constant, its average value is 9.8 mV. The electrochemical results correspond with the electronic spectra suggesting that the electron enters the half-filled dz2 orbital of the copper(II) atom.

Full paper in Portable Document Format: 593a166.pdf

Chemical Papers 59 (3) 166–173 (2005)