Synthesis and characterization of uranyl compounds with iminodiacetate and oxydiacetate displaying variable denticity

Jiang, J. and Sarsfield, M. J. and Renshaw, J. C. and Livens, F. R. and Collison, D. and Charnock, J. M. and Helliwell, M. and Eccles, H. (2002) Synthesis and characterization of uranyl compounds with iminodiacetate and oxydiacetate displaying variable denticity. Inorganic Chemistry, 41 (10). pp. 2799-2806. ISSN 0020-1669

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Abstract

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.