Effect of substituents on the structure of dioxouranium (VI) complexes of 7-carboxaldehyde-8-hydroxyquinoline and some of its schiff bases

A series of dioxouranium (VI) complexes with 7-carboxaldehyde-8hydroxyquinoline (oxine) and with some of its Schiff bases, LH, have been prepared and characterized by elemental analyses, electronic and vibrational spectral studies. All complexes except those of the oxine have the [UO2L2] . EtOH, stoichiometry (n=0, 1, 2 or 4). The uranyl complexes of the oxine have the formula [UO2L2(LH)]. The i.r. spectra reveal all ligands to be monobasic bidentate chelating agents coordinated to the uranium(VI) via the enolized phenolic OH and aldehydic oxygen or azomethine nitrogen atom. The force constant Fsub(U-O) (mdyn A) and the bond length rsub(U-O)(A) of the U-O bond are also calculated and related to the electronic properties of the p-substituents. (orig.)