Combination of covalent and hydrogen bonding in the formation of 3D uranyl-carboxylate networks

Four compounds containing uranyl cation [UO2](2+) have been synthesized hydrothermally by reacting uranyl acetate and uranyl nitrate with various N/O donor ligands. The structure of all compounds was elucidated by single crystal X-ray diffraction study. Compound [(UO2)(6-methylnicotinato)(3)](H3O)center dot 4H(2)O (1) is a discrete complex (0D), that gives rise in the crystal to hydrophilic channels, while [(UO2)(OH)(mu(2)-3-pyridylpropionato)](n) (2) and [(UO2)(H2O)(mu(3)-4,4'-oxybis(benzoato)](n) (3) show the formation of 1D coordination polymers. Moreover, oxalate anions, formed in situ by using 5-methylisophthalic or 2,3-pyrazinedicarboxylic acid as reactant ligands, gave rise to a 2D coordinating network [(UO2)(2)(mu(2)-oxalate)(mu(2)-OH)(2)(H2O)(2)](n)center dot nH(2)O (4). All the complexes expanded their dimensionality to 3D through hydrogen bonds. (C) 2010 Elsevier B.V. All rights reserved.