C-13 magnetic relaxation rates and H-1 and C-13 paramagnetic shifts of Co(II) complex of dopamine

Abstract

The importance of unpaired spin distribution in the Co(II)-Dopamine complex in aqueous solution, was investigated. From the analysis of the H-1 and C-13 isotropic shifts and with the aid of an INDO M.O. calculation on a dopamine radical a prevalent σ-type delocalization mechanism of the spin density was evidentiated, even if a contribution from π-electrons cannot be completely excluded.

The analysis of the spin-lattice relaxation rates revealed the importance of ligand-centered dipolar interactions. The introduction of the spin densities, calculated from the INDO method, in the modified Solomon-Bloembergen equation, allowed to estimate the correlation time of the complex which can be identified with the electronic relaxation time.