Ionic fullerene compounds containing negatively charged dimers and coordinatively bound anions

Abstract

The review summarizes the results of investigations of ionic fullerene compounds containing negatively charged dimers and fullerene anions coordinated to metalloporphyrins. Fullerene radical anions were found to form diamagnetic singly bonded (C60 −)2 and (C70 −)2 dimers. Dimerization is reversible and leads to paramagnetic—diamagnetic phase transitions or a decrease in the magnetic moment of the complexes. The temperature, at which dissociation of the (C60 −)2 dimers begins, varies from 140 to 320 K; the corresponding temperature for the (C70 −)2 dimers varies from 260 to 360 K and higher. We prepared the first doubly bonded (C60 −)2 dimer. At 300 K, this dimer exists as a biradical. The fullerene radical anions form Co—C coordination bonds with cobalt(II) porphyrinates. The resulting anions are diamagnetic. In some cases, Co—C coordination bonds undergo reversible dissociation, resulting in magnetic transitions from the diamagnetic to the paramagnetic state.