Synthesis and magnetic properties of cerium macrocyclic complexes with tetramethyldibenzotetraaza[14]annulene, tmtaaH(2)

The complexes [Ce(tmtaa)(2)], [Ce(tmtaa)(tmtaaH)] and [Ce-2(tmtaa)(3)(thf)(2)] are obtained from Ce[N(SiMe3)(2)](3) and tmtaaH(2), the macrocyclic ligand 6,8,15,17-tetramethyldibenzotetraaza[14]annulene, depending on the stoichiometry, solvent and temperature. The crystal structure of Ce(tmtaa)(2) is isostructural with Zr(tmtaa)(2), however magnetic susceptibility measurements in the range 5-300 K show that [Ce(tmtaa)(2)] is not diamagnetic, but is a temperature-independent paramagnet (TIP), similar to Ce(cot)(2), cerocene.