Synthesis and structures of vanadium-cerium trinuclear complexes with schiff-base ligands

A vanadium(V)-cerium(IV) trinuclear complex, [{V ^VO ₂(L ₁)} ₂Ce ^IV] (1) (H ₃L ₁: N,N′-bis-3-ethoxysalicylidene-2-hydroxy-1,3- propanediamine), was prepared by the reaction of [V ^IVO(acac) ₂] and [Ce ^III(acac) ₃]·3H ₂O with H ₃L ₁ in CH ₃CN, followed by oxidation of the product in air. The structure of complex 1 was determined by X-ray crystal structure analysis. The complex has a V ^V-Ce ^IV-V ^V trinuclear structure with two dioxovanadium(V) moieties on each side of the cerium(IV) moiety. Complex 1 has two L ₁ ligands to form a trinuclear structure. The basal oxo atoms of the dioxovanadium(V) moieties are coordinated to the cerium atom with Ce-O distances of 2.322(3) and 2.343(3) Å. The apical two non-coordinating oxo atoms are oriented to the same direction to form an endo structure. IR data of complex 1 show V=O stretching bands at 975 cm ^-1 for the apical non-coordinated oxo atoms and 802 cm ^-1 for the basal coordinated oxo atoms. The cyclic voltammogram of complex 1 in CH ₃CN shows a quasi-reversible two-electron redox couple with E _1/2 = -0.60 V vs Fc/Fc ⁺.