Crystal and molecular structure of uranyl(VI) complexes with acyclic and cyclic binucleating ligands

Abstract

The crystal and molecular structure of uranyl(VI) complexes with acyclic and cyclic binucleating ligands is reported. The acyclic complex was prepared by reaction of the Schiff base (H 4aapen), obtained by condensation of o-acetoacetylphenol and ethylenediamine, and dioxouranium salts in alcoholic media, recrystallizing the crude product from dimethylformamide. UO 2(H 2aapen)(dmf) is monoclinic, P2 1 n , a = 22.20(3), b = 8.70(1), c =13.86(2) A ̊ and β = 97.90(3) °; D c = 1.80 g cm −3 for Z = 4. The O-U-O group occupies the outer O 2O 2 compartment of the potentially binucleating ligand. The cyclic uranyl(VI) complex was obtained by condensation of 2,6 diformyl-4-chlorophenol and 1,5-diamino-3-thiapentane in the presence of uranyl(VI) diacetate or by reaction of the preformed ligand with uranyl(VI) diacetate. The compound crystallizes in the orthorhombic space group Pcba with eight formula units in a cell of dimensions a = 26.653(3), b = 22.871(3), c = 8.875(5) A ̊ . Five donor atoms, including sulphur, of the ligand are equatorially bonded to the uranyl group to form discrete monomeric molecules with the uranium atom in the usual pentagonal bipyramidal coordination geometry.