Eight uranyl compounds containing the dicarboxylate ligands iminodiacetate (IDA) or oxydiacetate (ODA) have been characterized in the solid state. The published polymeric structures for [UO2(C4H6NO4)(2)] and [UO2(C4H4O5)](n) have been confirmed, while Ba[UO2(C4H5NO4)(2)].3H(2)O, [(CH3)(2)NH(CH2)(2)NH(CH3)(2)][UO2(C4H4O5)(2)] [orthorhombic space group Pnma, a = 10.996(5) Angstrom, b = 21.42(1) Angstrom, c = 8.700(3) Angstrom, Z = 4], and [C2H5NH2(CH2)(2)NH2C2H5][UO2(C4H4O5)(2)] [monoclinic space group P2(1)/n, a = 6.857(3) Angstrom, b = 9.209(5) Angstrom, c = 16.410(7) Angstrom, beta = 91.69(3), Z = 2] contain monomeric anions. The distance from the uranium atom to the central heteroatom (0 or N) in the ligand varies. Crystallographic study shows that U-heteroatom (O/N) distances fall into two groups, one 2.6-2.7 Angstrom in length and one 3.1-3.2 Angstrom, the latter implying no bonding interaction, By contrast, EXAFS analysis of bulk samples suggests that either a long U-heteroatom (O/N) distance (2.9 Angstrom) or a range of distances may be present. Three possible structural types, two symmetric and one asymmetric, are identified on the basis of these results and on solid-state C-13 NMR spectroscopy. The two ligands in the complex can be 1,4,7-tridentate, giving five-membered rings, or 1,7-bidentate, to form an eight-membered ring. (C4H12N2)[(UO2)(2)(C4H5NO4)(2)(OH)(2)].8H(2)O [monoclinic space group P2(1)/a, a = 7,955(g) Angstrom, b = 24.050(8) Angstrom, c = 8.223(6) Angstrom, beta = 112.24(6), Z = 2], (C2H10N2)[(UO2)(2)(C4H5NO5)(2)(OH)(2)].4H(2)O, and (C6H13N4)(2)[(UO2)(2)(C4H4O5)(2)(OH)(2)].2H(2)O [monoclinic space group C2/m, a = 19.024(9) Angstrom, b = 7.462(4) Angstrom, c = 2.467(6) Angstrom, beta = 107.75(4), Z = 4] have a dimeric structure with two capping tridentate ligands and two mu(2)-hydroxo bridges, giving edge-sharing pentagonal bipyramids.
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