New Tetraazaannulene Hosts for Fullerenes

Two modifications to the doubly concaved host molecules based on well-known nickel tetraazaannulene complexes have resulted in the preparation of the compounds Ni(NapTMTAA)·2benzene, 1,6,8,15,17-tetramethyldinapthalene-5,9,14,18-tetraazacyclotetradecinatonickel(II), and Ni(Cl4TMTAA)·CH2Cl2, 2,3,11,12-tetrachloro-6,8,15,17-tetramethyldibenzo-5,9,14,18-tetraazacyclotetradecinatonickel(II). When crystallized with C60 in carbon disulfide, the crystalline, well-ordered, host−guest compounds Ni(NapTMTAA)·C60·2CS2 and Ni(Cl4TMTAA)·C60·2CS2 were formed. The compounds were characterized by X-ray crystallography. The crystal structures of the precursor host molecules showed very strong host−host interactions, particularly in the case of Ni(Cl4TMTAA), which had short Ni···Ni interactions of 3.3860(11) and 3.5888(11) Å in the two different dimers in the asymmetric unit; yet, these host−host interactions were entirely destroyed in the resultant host−guest compounds, and C60 molecules were shown to make use of both cusps of the host macrocycle in the formation of a shape-selective arrangement.