Dioxouranium(VI) complexes of monobasic bidentate and bibasic tetradentate Schiff bases

Abstract

A series of dioxouranium(VI) complexes were sythesised with the bidentate Schiff base ligands obtained by condensation of salicylaldehyde with aniline (pBH) or benzylamine (bBH), and the tetradentate Schiff base ligands derived by condensation of salicylaldehyde with ehtylenediamine (SpH 2). The bidentate ligands formed complexes of the type UO 2X 2(pBH) n where X = NO − 3, n = 2; X = CH 3COO −, n = 1, and also the complexes UO 2Cl 2(pBH) 2·H 2O, UO 2(CH 3COO)(bBH)·H 2O and UO 2SO 4(bBH)·EtOH·H 2O. The tetradentate ligands formed the complexes UO 2Cl 2(SBH 2)·EtOH, UO 2SO 4(SBH) 1/2·EtOH·2H 2O and also UO 2Cl 2(SpH 2) 1.5·2H 2O, UO 2(NO 3) 2(SpH 2) 1.5·EtOH and UO 2(Sp)·EtOH. Conductivity measuremetns indicate that all the complexes are non-electrolytes in MeNO 2 or MeCN solutions. IR spectral data suggest that the molecules and not the anions of the schiff base are coordinated to the central uranium atom, except for the complexes UO 2(CH 3COO)bB·H 2O and UO 2(Sp)·EtOH in which the deprotonated binegative ion is coordinated to the uranyl group. The acetato and sulphato groups are coordianted as bidentate ligands, while the nitrato group behaves as a unidentate ligand in the pBH complexes and as a bidentate ligand in the SpH 2 complex.