An electrochemical study of solvent-complex interactions in trans-1,2-diaminocyclohexane- N, N, N', N'-tetraacetatochromate(III) and 1,2-diaminoethane- n-hydroxyethyl- N, N', N'-triacetatochromium(III)

Abstract

The electroreduction of trans-1,2-diaminocyclohexane- N, N, N', N'-Tetraacetatochromate(III) and 1,2-diaminoethane- N-hydroxyethyl- N, N', N'-triacetatochromium(III) has been investigated in different solvents on a mercury electrode by convolution potential sweep voltammetry. The dependence of the observed diffusion coefficients, standard potentials and double layer corrected electron transfer rates on solvent properties has been interpreted. It has been shown that the formal potentials for the reduction of both complexes are linear functions of the solvent acceptor numbers. The logarithm of the corrected standard rate constant for the trans-1,2-diaminocyclohexane- N,N,N',N'-tetraacetato complex depends on both the acceptor number and the logarithm of the solvent's longitudinal relaxation time. On the other hand in case of the 1,2-diaminoethane- N-hydroxyethyl- N, N', N'-triacetato complex, this quantity depends on the solvent's acceptor and donor number. It is concluded that the 1,2-diaminoethane- N-hydroxyethyl- N, N', N'-triacetatochromium(III) complex undergoes substitution of the coordinated water molecule originally present as a ligand. However, for the trans-1,2-diaminocyclohexane- N, N, N', N'-tetraacetato chromium( III) complex there is no indication of the incorporation of solvent molecules in the first coordination sphere as a ligand.