OXIDATION-REDUCTION CHEMISTRY OF COORDINATION COMPLEXES WITH MACROCYCLIC LIGANDS . CU(TRANS[14]DIENE)+-CU(TRANS[14]DIENE)2+ SYSTEM . ELECTROCHEMICAL, SPECTRAL, AND SOLUTION STUDIES

The very careful electrolytic reduction of the macrocyclic Schiff base amine-copper(II) complex Cu(trans[14]diene)2+ yields a highly reactive yellow complex which appears to be Cu(trans[14]diene)+. The cathodic reduction of Cu(trans[14]-diene)2+ has been examined polarographically and by controlled-potential electrolysis and the conditions for the formation of Cu(trans[14]diene)+ are described. The Cu(trans[14]diene)2+, -couple is strongly reducing, probably indicating that the ligand provides a somewhat unfavorable coordination environment for copper(I). Comparison of the ultraviolet spectra of Cu(trans[14]diene)2+, Cu(trans[14]diene)+, and several M(trans[14]diene)2+ complexes reveals some systematic variations in the energies of absorption maxima; it is suggested that these ultraviolet and near-ultraviolet absorption bands should be assigned to metal-to-ligand charge-transfer transitions. © 1969, American Chemical Society. All rights reserved.