Equatorial ligand effects on the visible spectra of dioxouranium(VI) complexes in solution

Abstract

The visible spectra of [UO₂L₅]²⁺, where L = OCMe(NMe₂), OCMe(NHMe), OCH(NMe₂), OCH(NHMe), OP(OMe)₃ and OPMe(OMe)₂ ; and [UO₂ {OP(NMe₂)₃}]²⁺, in CH₂Cl₂ solution are reported. The spectra have been resolved into 13, 14 or 15 bands depending on the complex. These bands exhibit variations in both frequency and molar absorptivity which are consistent with the nature of the equatorial ligands in the equatorial plane about the UO₂²⁺ axis being of major importance in determining the nature of the spectra. The overall influence of the equatorial ligands on the dioxouranium(VI) spectra appears to be determined by the combined effects of stereochemistry and ligand electron-donating ability.