ELECTRONIC STRUCTURE OF (CATECHOLATO)(1,10-PHENANTHROLINE)COPPER(II): INTRAMOLECULAR INTERLIGAND ELECTRONIC INTERACTIONS

Abstract

The electronic absorption spectrum of (catecholato)(1,10-phenanthroline)copper(II) ([Cu(cat)(phen)]) measured in 1:1 methanol and water was compared with those of (catecholato)(ethylenediamine)copper(II) ([Cu(cat)(en)]) and (oxalato)(1,10-phenanthroline)copper(II) ([Cu(ox)(phen)]). From the above results together with MO calculations and polarization spectra using stretched PVA films, it is found that the 330, 295.0, 275.0, 267, 233, and 223 nm bands of [Cu(cat)(phen)] are due to transitions localized on the phen moiety, and the 292 and 210.0 nm bands on the cat moiety. The 209 nm band of [Cu(cat)(phen)] can be interpreted as arising from a mixture of two kinds of transitions localized on phen and cat. This implies that the two π-electronic systems, being usually considered to exist independently on the two moieties, can interact greatly, as newly reported here.

Key Words:

• copper(II)
• phenanthroline
• catecholate
• electronic spectra
• polarized spectra
• MO calculations.