Multi-dimensional π-π stacking interaction in neutral radical crystals obtained by electrochemical oxidation of [CoIII(2,3-Nc)(CN)2]- (2,3-Nc=2,3-naphthalocyanine)

Electrochemical oxidation of the dicyano(2,3-naphthalocyanato)cobalt(III) anion ([Co(2,3-Nc)(CN)(2)](-)) yields electrically conducting crystals comprised of the Co(2,3-Nc)(CN)(2) neutral radicals and some crystal solvents. The oxidation of the potassium salt in acetonitrile gives Co(2,3-Nc)(CN)(2). CH3CN, while that in a mixed solvent of acetonitrile/o-dichlorobenzene (DCB) gives Co(2,3-Nc)(CN)(2). 2DCB. X-Ray structure analyses show that two- or three-dimensional pi-pi stacking interactions are achieved in these crystals. Compared with the phthalocyanine (Pc) derivatives this higher-dimensionality in the 2,3-Nc radical crystals, even with a large crystal solvent, arises from the linear extension of the pi-conjugation system of Pc.