Imidazolin-2-iminato Cerium(IV) Chlorides: Synthesis, Structure and Electrochemical Properties

The ligand field greatly affects the redox properties of cerium. Herein, cerium(III) and cerium(IV) complexes supported by imidazolin-2-iminato ligands were synthesized and structurally characterized, and their electrochemical properties were investigated. Silylamine elimination of cerium(III) amide Ce{N(SiMe3)(2)}(3) with imidazolin-2-imine Im(R)NH (R=Mes, tBu, iPr) provided imidazolin-2-iminato cerium(III) complexes, [(Im(Mes)N)(Im(Mes)NH)Ce{N(SiMe3)(2)}(2)] (1), [(Im(tBu)N)(2)(Im(tBu)NH)Ce{N(SiMe3)(2)}] (2) and [(Im(iPr)N)(2)(Im(iPr)NH)Ce-(mu-Im(iPr)N)](2) (4) in 71-85% yields. These cerium(III) complexes were successfully oxidized by Ph3CCl or C2Cl6 to afford imidazolin-2-iminato cerium(IV) chlorides, [(Im(Mes)N)(2)Ce{N-(SiMe3)(2)}Cl] (5), [(Im(tBu)N)(3)CeCl] (6) and [(Im(iPr)N)(2)Ce(mu-Im(iPr)N)Cl](2) (7) in 70%-76% yields. All complexes were characterized by the single-crystal X-ray diffraction, which showed that 1, 2, 5 and 6 are monomers while 4 and 7 are dimers. The electrochemical studies indicated that the Ce(III/IV) couples for 5 and 6 are more negative than those of silylamido cerium(IV) complexes, and the Ce(III/IV) couples for 1 and 2 have a similar trend.

Automated summary

This study synthesized and characterized cerium(III) and cerium(IV) complexes supported by imidazolin-2-iminato ligands, and investigated their electrochemical properties.