Uranyl ion complexes with aminoalcoholbis(phenolate) [O,N,O,O'] donor ligands

The reaction between uranyl nitrate hexahydrate and phenolic ligand precursor NN-bis(2-hydroxy-3,5-dimethylbenzyl)-2-aminoethanol (H(3)L1) in acetonitrile without base affords the dinuclear uranyl complex [(UO2)(2)(H(2)L1)(2)(NO3)(2)] (1); in the presence of base, the mononuclear complex [UO2(H(2)L1)(2)](.) 2H(2)O (2) is formed. Ligand NN-bis(2-hydroxy-5-t-butyl-3-methylbenzyl)-2-aminoethanol (H(3)L2) affords a uranyl complex of formula [UO2(H(2)L2)(2)](center dot)2CH(3)CN (3); ligand N,N-bis(2-hydroxy-3,5-dimethylbenzyl)-3-amino-1-propanol (H(3)L3) affords a uranyl complex of formula [UO2(H(2)L3)(2)] (4); whilst ligand NN-bis(2-hydroxy-5-t-butyl-3-methylbenzyl)-3amino- 1-propanol (H(3)L4), used as the hydrochloride, affords a uranyl complex of formula [UO2(H(2)L4)(2)] (5). A solid complex with uranyl ion could not be formed using the ligand NN-bis(2-hydroxy-3,5-di-t-butylbenzyl)-2-aminoethanol. The molecular structures of 1-5 were verified by X-ray crystallography whereby it was ascertained that 1 is a dialkoxo-bridged dinuclear uranyl complex with a U to L ratio of 1:1. The other complexes 2-5 form in a molar ratio of 1:2 (U to L) and bear similar mononuclear, distorted octahedral uranyl structures with the four coordinating phenoxo ligands forming an equatorial plane and resulting in a centrosymmetric structure for the uranyl ion. (c) 2005 Elsevier Ltd. All rights reserved.