ELECTROCHEMISTRY AND SPECTROSCOPY OF MAGNESIUM OCTAETHYLTETRAAZAPORPHYRIN AND MAGNESIUM OCTAKIS(METHYLTHIO)TETRAAZAPORPHYRIN

Electrochemical properties, absorption and magnetic circular dichroism (MCD) spectra are reported for two peripherally substituted tetraazap orphyrins (TAP). Data are described for magnesium octaethyltetraazapor phyrin (MgOETAP) and magnesium oc-takis(methylthio)tetraazaporphyrin ( MgOMTTAP) in dichloromethane (DCM) and N,N-dimethylformamide (DMF) sol utions. Differential pulse Voltammograms (DPV) and cyclic voltammogram s (CV) measurements yielded epsilon(1/2) values of: +0.81 V forming th e ring oxidized pi cation [MgOETAP(-1)](+), -0.70 V forming the ring r educed pi anion [MgOETAP(-3)](-) and -1.15 V forming the ring reduced pi dianion [MgOETAP(-4)](2-)) and E(1/2) values of 0.95 V forming the oxidized pi cation [MgOMTTAP(-1)](+), -0.68 V forming the ring reduced pi dianion [MgOMTTAP(-4)](2-) and -1.05 V forming the ring reduced pi dianion [MgOMTTAP(-4)](2-). Band deconvolution calculations, that cou ple the absorption and the MCD spectra, are reported for both compound s. The energies of the fitted bands are compared with experimental res ults for magnesium phthalocyanine reported by Ough et al. [E.A. Ough, T.N. Nyokong, K.A.M. Creber and M.J. Stillman, Inorg. Chem., 27 (1988) 2725]. Deconvolution analysis isolated an additional degenerate trans ition in the Q band region (700-500 nm), which has been assigned as a vibrational component of the Q band. Individual electronic transitions (assignments) are located at: 595 (Q(00)), 570 (Q(01)), 342 (B1), and 327 nm (B2) for MgOETAP and at: 663 (Q(00)), 611 (Q(02)), 374 (B1), 3 52 (B2), and 250 nm (L) for MgOMTTAP.