First Structural Evidence of Actinide−Nitrite Coordination

Abstract

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.

Role of the Hydroxo Group in the Coordination of Citric Acid to Trivalent Americium

“…These calculated distances are consistent with Am‐O distances reported in the Cambridge Structural Data base (CSD); Am‐COO – (monodentate) distances range from 2.38 to 2.55 Å, , and Am‐OH 2 distance is 2.513 Å . These values are also consistent with the one determined for Eu‐lactate or Am‐formate systems from DFT.…”

“…For instance, the shape of the Fourier transform EXAFS spectra in Figure (right) confirms a different coordination mode, suspected from the visible absorption spectroscopy, for the 1:1 Am‐citric acid complex at pH 1 vs. the 1:1 Am‐citric acid complex at pH 3. To further analyze the resulting EXAFS spectra, theoretical fits were performed based on crystallographic references , . During this procedure, a shell fit was applied incrementing step by step the number of shells to fit the data.…”

“…leading to different coordination modes. In terms of solid‐state structure, two Am(III) complexes with citric acid were characterized by single‐crystal X‐ray diffraction (SC‐XRD) , . Two trimeric complexes, [Co(NH 3 ) 6 ] 2 K[Am 3 (Cit) 4 (H 2 O) 3 ].18H 2 O and (NH 4 ) 2 (Co(NH 3 ) 6 ) 2 [Am 3 (Cit) 4 (OH)(H 2 O) 2 ].nH 2 O, were obtained from a neutral solution above pH 7.…”

Interaction of transuranium elements with biologically relevant ligands. Synthesis, crystal structure, IR and electronic spectra of neptunium glycolate [NpO2(C2O3H3)(Bipy)]·2.5H2O

“…Previously, we have reported on behavior of Np(V) in the presence of various N-and S-containing ligands [1][2][3][4]. Np(V) being the ''hard acid" has high affinity to the coordination of N-and S-donor ligands and formation of stable metallocycles [5].…”

“…The first compound contains bidentate glycolate-ions, while in the second complex the glycolic acid is suggested to be dianion C 2 O 3 H 2À 2 and functions as tridentate bridging ligand coordinating four U centers. This is the rare example of deprotonation of OH group in the aliphatic hydroxo monocarboxylic acid [16] As a result, the 2D crystal structure is formed consisting of [(UO 2 ) 4 (O) 2 [5].…”