A series of isostructural oxalates of Th, U, Np, and Pu have been synthesized. The crystal structure of {C(NH(2))(3)}(4)[An(C(2)O(4))(4)]·2H(2)O comprises infinite [An(C(2)O(4))(4)](4n-) chains, guanidinium cations and water molecules. Each An atom is connected to five oxalate anions, two of which act as bridging tetradentate ligands, while the other three function as terminating bidentate ligands. Electron and IR spectra of the compounds as well as the results of thermal analysis correlate with their structure. An actinide contraction effect is demonstrated by a decrease in the An-O interatomic distances and the volumes of An atom coordination polyhedra and Voronoi-Dirichlet polyhedra. Ten-coordinate An oxalates are discussed in terms of continuous shape measures approach.

This study concerns the formation of complexes with actinides at oxidation state +IV, from Th to Am, through a lacunary heteropolyanion ligand P(2)W(17)O(61)(10-). The preparation of original single crystals of complexes with 1:2 stoichiometry provided structural data through single-crystal X-ray diffraction for the entire An(IV) series. An(IV) atoms in these complexes have a coordination number of 8, and their coordination polyhedron is a distorted square antiprism. The data were used to compute a mean (An-O) interatomic distance for each actinide. When the interatomic distance is plotted versus the inverse ionic radius of these tetravalent actinides, it appears that the simple electrostatic model is not suitable for Am(IV) and Pu(IV), although this trend must be confirmed by further investigation with other examples from the An(IV) series.

The first nitrite complex of actinide metal, {C(NH 2)3}2[NpO 2(NO 2)(Pic)2], was synthesized, and its crystal structure was determined using X-ray diffractometry and confirmed by NIR and IR spectroscopies. Main crystallographic data: space group P1, triclinic, a = 8.9329(1) A, b = 11.6669(2) A, c = 11.6698(2) A, alpha = 68.080(1) degrees, beta = 88.213(1) degrees, gamma = 73.254(1) degrees, V = 1076.45(3) A (3), and Z = 2.

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The first complex of a transuranium element (tetravalent plutonium) with nucleotide (deoxycytidinemonophosphate, dCMP) was synthesized and structurally characterized. The crystal structure of [Pu(4)(NO(3))(8)(HdCMP)(4)(H(2)O)(8)](NO(3))(4).2H(2)O consists of complex cations [Pu(4)(NO(3))(8)(HdCMP)(4)(H(2)O)(8)](4+), NO(3)(-) anions, and water molecules. There are two crystallographically independent Pu atoms in the structure, both having similar surroundings. Each of the Pu atoms is coordinated by three O atoms of phosphate groups belonging to three different (HdCMP)(-) anions, two bidentate nitrate anions, and two water molecules. The crystal structure is confirmed by IR and UV/vis/near-IR spectroscopic data.