Synthesis and magnetic properties of cerium macrocyclic complexes with tetramethyldibenzotetraaza[14]annulene, tmtaaH2

Abstract

The complexes [Ce(tmtaa)2], [Ce(tmtaa)(tmtaaH)] and [Ce2(tmtaa)3(thf)2] are obtained from Ce[N(SiMe3)2]3 and tmtaaH2, 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.