Cocrystallites consisting of metal macrocycles with fullerenes

The cocrystallites that contain C₆₀, C₇₀ and endohedral metallofullerenes with metal complexes of macrocycles are reviewed. Metal complexes of porphyrin cocrystallites with fullerenes form solids with remarkably close contact between the curved π surface of a fullerene and the planar π surface of a porphyrin, without the need for matching convex with concave surfaces. The structures of metal octaethylporphyrins (oeps) in C₆₀·Pd(II)(oep)·1.5C₆H₆, C₆₀·Cu(II)(oep)·2C₆H₆, C₆₀·Ag(II)(oep)·2C₆H₆ and C₆₀·2Ni(II)(oep)·2C₆H₅Cl reveal the remarkable anti-formed oep configurations, with the four ethyl groups of the metal oep portions lying on both the same and the opposite sides of the porphyrin plane toward the C₆₀. On the other hand, syn-formed metal oeps are observed in the many cases of metal oep compounds, suggesting that there is a face-to-face interaction between two adjacent oep planes. A new cocrystallite which exhibits a strong intermolecular interaction between fullerene C₆₀ and the Co(tbp) is also reviewed, where tbp denotes a dianion of tetra(bis-tert-butylphenyl)porphyrin. The intermolecular interactions of the anti- and syn-formed metal oeps in the cocrystallites containing fullerenes are also described by DV-Xα molecular orbital calculation.