Binuclear metal complexes. 1. Synthesis, characterization, and electrochemical studies of dicopper(II) complexes with 4-methyl-2,6-di(acyl/benzoyl)phenol

Synthesis and characterization of the mono- and binuclear copper (II) complexes, Cu (R, R’)L2.H2O and Cu2(R,R’)L2.(ClO4)2.2H2O, have been made with the ligands 4-methyl-2,6-di(acyl/benzoyl)phenol, designated as (R,R’)HL, where R and R’ stand for the substituents in the de(acyl/benzoyl) moiety. The following substituents have been used : R = R’ = H, Me, Pr, Ph; R = Ph, R’ = Me. Electrochemical studies of these compounds have been made in DMF with use of a evidenced from cyclic voltammetric and coulometric measurements. Among these, the electron-transfer processes in Cu2(Ph,Ph)L2(ClO4)2.2H2O and Cu2(Ph,Me)L2(ClO4)2.2H2O occur reversibly; others show quasi-reversible behavior. The E1/2 values are about -0.05 V vs. SCE. The electrochemically reduced Cu1Cu1 species show an absorption band at 470 nm. The mononuclear copper(II) complexes undergo quasi-reversible reduction with E1/2 ≅ -0.43 V