Photochemistry of Dithiocarbamate Cu(S2CNEt2)2 Complex in CHCl3. Transient Species and TD-DFT Calculations.

Abstract

Nanosecond laser flash photolysis was used to study the mechanism of photochemical transformations of the diethyldithiocarbamate Cu(II) complex (Cu(dtc)2, where dtc- ≡ -S2CNEt2 anion) in chloroform solutions. The electron transfer from the excited Cu(dtc)2 complex to a solvent molecule leads to the appearance of the primary intermediate, the [ClCu(dtc)(dtcCHCl2)] complex, where a dtcCHCl2 molecule is coordinated with a copper ion via one sulfur atom. In the fast reaction (k = 2.1 × 109 M-1 s-1) with Cu(dtc)2, this complex forms a long-lived dimer [ClCu(dtc)(dtcCHCl2)Cu(dtc)2]. This intermediate decays during several seconds (k = 5.6 × 10-2 s-1) into the final product, i.e., a diamagnetic dimer [ClCu(dtc)Cu(dtc)2]. To determine the structure of intermediate complexes the quantum chemical calculations were carried out using DFT, TD-DFT, and PCM (Polarizable Continuum Model) methods.