ELECTRON-TRANSFER KINETICS FOR WEAKLY BONDED, LABILE METAL-LIGAND COMPLEXES

The electron transfer kinetics for the weakly-bonded, labile Cu-I-L (L = CO and ethene) complexes have been investigated with square-wave vo ltammetry (SWV) in the ionic liquid solvent AlCl3-EMIC (EMIC = 1-ethyl -3-methyl-1H-imidazolium chloride). The oxidation of Cu-I-L to Cu-II a nd free ligand proceeds through an asymmetric quasi-reversible electro n transfer mechanism in which the heterogeneous rate constant (k(a)(0) ) is decreased relative to the rate constant for uncomplexed Cu-I, and the anodic transfer coefficient (beta) is much less than 0.5. The Cu- I-L bond energies were determined using potentiomtric methods and foun d to be 9.4 (+/-0.8) and 11.1 (+/-0.1) kcal mol(-1) for the CO and eth ene complexes, respectively.