Redox Chemistry of Tetrakis[5,6-di(2-pyridyl)-2,3-pyrazino]porphyrazinatocobalt(II): Isolation and Characterization of Solid Pure Co(I), Co(II) and Co(III) Complexes

Salt-like hydrated complexes of formulae Na[Py(8)TPyzPzCo] and [Py(8)TPyzPzCo](SbCl(6)) containing Col and Co(III), respectively, and the neutral Co(II)-bis(dimethyl sulfoxide) (DMSO) adduct [Py(8)TPyzPzCo(DMSO)(2)], bearing additional clath-rated DMSO molecules, have been prepared and characterized {Py(8)TPyzPz = tetrakis[5,6-di(2-pyridyl)-2,3-pyrazino]porphyrazinato dianion}. The sodium CO(I) salt, the anion of which, [Py8TPyzPzCo](1-), had previously been identified by electrochemical solution studies, represents the first example of a Col derivative of a tetrapyrrolic macrocyclic chromophore prepared as a solid pure material. Solutions of Na[Py(8)TPyzPzCo] in DMSO, under defined experimental conditions, allow the slow formation (months) of crystals of its corresponding Co(II) complex of formula [Py(8)TPyzPzCo-(DMSO)(2)]center dot 6DMSO. The structure of the adduct, elucidated by single-crystal X-ray analysis, shows the central Coll ion surrounded by the four pyrrole N atoms of the porphyrazine macrocycle and two O atoms of the axially bonded DMSO molecules. Oxidation of the basic starting material [Py(8)TPyzPzCo] with phenoxathiin hexachloroantimonate (phenox-SbCl(6)) led to the formation of the Co(III) complex [Py(8)TPyzPzCo](SbCl(6);). Full characterization of the title Co(I), Co(II), and Co(III) species has been accomplished by solution studies and from IR, UV/Vis, EPR and X-ray crystallography data.