EPR study on the chemistry and photochemistry of copper(II) dithiocarbamate mixed-ligand complexes

The thermal and photochemical reactions of the 1 : 1 mixed-ligand complexes Cu(dtc)X (X = Cl-, NO3-, ClO4-) have been studied on the ground of their EPR spectra in acetone, CCl4/i-PrOH (1 : 1), and CHCl4/i-PrOH (1 : 1) solutions. The study allows us to get some insight into the behaviour of the mixed-ligand Cu-II(dtc)X complexes with respect to the acceptor properties of halocarbons. In CCl4/i-PrOH (1 : 1) both Cu-II(dtc)(+)...NO3- and Cu-II(dtc)(+)...ClO4- undergo thermal reactions within their donor-acceptor complexes with CCl4 to yield Cu(dtc)Cl. On the time scale of the experiment the reaction does not occur thermally in CHCl3/i-PrOH (1 : 1), but occurs photochemically in both halocarbon/i-PrOH (1 : 1) systems in which Cu(dtc)Cl is further photolyzed to CuCl2. Continuous photolysis of the title compounds in acetone simply bleaches the solution without any intermediate EPR or light absorption.