Vanadium complexes with multidentate amine bisphenols

摘要

The reaction of VO(acac)_2 (acac~? = acetyl acetonate) with tripodal glycine bisphenol H_3L~1 under an ambient atmosphere yields a hexacoordinated vanadium(IV) complex [V(acac)(L~1)] (1). The corresponding reactions with tripodal 2-propanolamine bisphenol H_3L~2 and potentially pentadentate ethoxyethanolamine bisphenol H_3L~3 lead to the oxidation of the metal centre and formation of mononuclear oxovanadium(V) complexes [VO(L~2)] (2) and [VO(L~3)] (3), respectively. Alternatively, these latter two complexes can be prepared using VOSO_4·5H_2O or VO(OPr)_3 as a precursor. The CV of 1 in an ACN solution shows a reversible one-electron process at E_(1/2) = +1.18 V, whereas 2 and 3 have an irreversible redox response at ?1.6 V and ?1.2 V, respectively. Complexes 2 and 3 show moderate activity in the epoxidation of cis-cyclooctene by tert-BuOOH at 50 ℃.