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

Spectrochemical and Electrochemical Properties of Distorted Pentacoordinate [Cu(chel)₂X]Y Complexes

G. Ondrejovič, A. Kotočová, and D. Valigura

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

E-mail: ondrejov@chtf.stuba.sk

Received: 7 September 2001

Abstract: The trigonal bipyramidal complexes of the general formula [Cu(chel)₂X]ClO₄, where chel = 2,2
- bipyridine (bpy), 1,10-phenanthroline (phen); X = Cl⁻, Br⁻, I⁻, NCS⁻, CN⁻, were prepared and their electronic absorption spectra were measured in Nujol mull and nitromethane solution. Using Hathaway’s electronic criteria the square-based pyramidal distortion of the trigonal bipyramidal coordination of the complexes in the solid state as well as in nitromethane solutions was analyzed. The electronic spectra indicate that the solid bpy complexes are more distorted than their phen analogues, the greatest difference being found for chloro and the smallest for isothiocyanato complexes. The electronic spectra of some complexes in nitromethane indicate square-based pyramidal distorted trigonal bipyramidal coordinations, while another indicate near trigonal bipyramidal coordinations. The halfwave potentials of complexes in nitromethane, except cyano complexes were in the range −0.40 V— −0.32 V for bpy and −0.43 V— −0.34 V for phen complexes vs. ferrocenium/ferrocene couple. A linear correlation between the halfwave potentials and the standard electrode potentials Eº(X₂/X⁻) was found for both series of bpy and phen [Cu(chel)₂X]ClO₄ complexes in nitromethane indicating that the redox properties of the [Cu(chel)₂X]ClO₄ complexes are predominantly affected by the nature of the ligands X.

Full paper in Portable Document Format: 563a168.pdf

Chemical Papers 56 (3) 168–173 (2002)