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] ·3H2O, [(CH3)2NH(CH2)2 NH(CH3)2][UO2(C4H4 O5)2] [orthorhombic space group Pnma, a = 10.996(5) Å, b = 21.42(1) Å, c = 8.700(3) Å, Z = 4], and [C2H5NH2(CH2)2NH 2C2H5][UO2 (C4H4O5)2] [monoclinic space group P21/n, a = 6.857(3) Å, b = 9.209(5) Å, c = 16.410(7) Å, β = 91.69(3), Z = 2] contain monomeric anions. The distance from the uranium atom to the central heteroatom (O or N) in the ligand varies. Crystallographic study shows that U-heteroatom (O/N) distances fall into two groups, one 2.6-2.7 Å in length and one 3.1-3.2 Å, 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 Å) 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 13C 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(C4H5 NO4)2(OH)2]·8H2O, [monoclinic space group P21/a, a = 7.955(9) Å, b = 24.050(8) Å, c = 8.223(6) Å, β = 112.24(6), Z = 2], (C2H10N2) [(UO2)2(C4H5 NO4)2(OH)2]·4H2O, and (C6H13N4)2 [(UO2)2 (C4H4O5)2(OH)2] ·2H2O [monoclinic space group C2/m, a = 19.024-(9) Å, b = 7.462(4) Å, c = 2.467(6) Å, β = 107.75(4), Z = 4] have a dimeric structure with two capping tridentate ligands and two μ2-hydroxo bridges, giving edge-sharing pentagonal bipyramids.
- uranyl compounds
- oxydiacetate displaying variable denticity