ELECTROCHEMISTRY ELECTRON PARAMAGNETIC RESONANCE AND VISIBLE SPECTRA OF COBALT NICKEL COPPER AND METAL-FREE PHTHALOCYANINES IN DIMETHYL SULFOXIDE

Half-wave potentials for tetrasulfonated divalent Co, Ni, Cu, and metal-free phthalocyanines were determined in dimethyl sulfoxide at rotating platinum and dropping mercury electrodes for both oxidation and reduction processes. Cyclic voltammetry and controlled-potential coulometry were used to establish the stabilities of the reduced species and the number of electrons involved in each step. Epr spectra of the Co and Cu starting materials, of the one-electron reduction products of the Ni and metal-free compounds, and of the two-electron reduction products of the Co and Cu species were obtained at 77 and 298 °K. Electronic absorption spectra were obtained for the compounds and for their one- and, with the exception of Co, two-electron reduction products. For the Cu, Ni, and metal-free compounds the data show reduction to involve only the ligand. For Co, first-step reduction yields Co(I). The data for the second-step reduction are interpreted in terms of initial reduction to Co(0) and subsequent formation of a reactive hydride. © 1968, American Chemical Society. All rights reserved.