Structure of the Sodium Salt of the Ternary Uranyl--Picolinate--Fluoride Complex [UO2(picolinate)F3] Na2(H2O)4.

Structural Role of Isonicotinic Acid in U(VI), Np(VI), and Pu(VI) Complexes with TcO4–, ReO4–, and ClO4– Ions

“…We accounted for this factor when choosing organic ligands for synthesis of An­(VI) with TcO 4 – , ReO 4 – , and ClO 4 – anions. Interaction of An­(VI) with pyridine-2-carboxylic (picolinic) acid normally leads to the formation of strong chelate metallorings, and it is hardly possible that TcO 4 – , ReO 4 – , or ClO 4 – anions will coordinate an An atom in the presence of picolinic acid in contrast to the complexes with more strong ligands such as [(UO 2 )­(pic)­(OH)], [(UO 2 )­(pic) 2 (C 2 O 4 )], Na 2 [UO 2 (pic)­F 3 ]·4H 2 O, [(UO 2 ) 2 CrO 4 (pic) 4 ]·2H 2 O, and [UO 2 (H 2 O) 5 ]­[(UO 2 ) 2 Cr 2 O 7 (pic) 4 ] . For pyridine-3-carboxylic (nicotinic) acid, formation of chelates is sterically hindered and N atom either does not participate in coordination of metal atoms (for example, [UO 2 (nic) 2 (H 2 O) 2 ]) or coordinates different metal sites, which leads to the formation of polymeric structures, as in [UO 2 Cu­(nic) 2 (NO 3 ) 2 ] where uranyl ion is a bridge between Cu atoms which, in turn, are coordinated by N atoms of nicotinic acid.…”

Two uranyl–organic frameworks with pyridinecarboxylate ligands. A novel heterometallic uranyl–copper(II) complex with a cation–cation interaction

“…The related ligands pyrazinetetracarboxylic and pyrazine-2,3-dicarboxylic acids were also shown to be useful ligands for the synthesis of uranyl-organic frameworks, both homo-and heterometallic [3]. Pyridine-2-carboxylic acid (or a-picolinic acid, denoted HL 1 hereafter) is an O,N-chelating ligand for uranyl (chelation is still possible even for the longer-armed 2-pyridylacetic acid [4]), but it has seldom been used in this context since only two crystal structures of its uranyl complexes are reported in the Cambridge Structural Database (Version 5.30) [5], one of them an anionic discrete species with three fluorine atoms completing the metal coordination sphere [6] and the other a neutral trimetallic complex obtained at room temperature [7]. For the sake of comparison with the latter, it appeared worthwhile to investigate the complexation of uranyl by HL 1 under hydrothermal conditions, and the result obtained is presented herein.…”

CuPYDC Metalloligands and Postsynthetic Rearrangement/Metalation as Routes to Bimetallic Uranyl Containing Hybrid Materials: Syntheses, Structures, and Fluorescence

“…Upon the comparison of 1 to the monometallic uranyl bearing hybrid materials formed with 2,4PYDC, , we find that the “prepackaged” Cu(II) metal center may have played a role in influencing the resulting topology. In monometallic U-PYDC compounds , (Figure ) and materials formed with analogous ligands − (e.g., pyridine-2-carboxylate and pyrazine-2-carboxylate), the N,O-site is typically occupied by UO 2 2+ . Although there are examples of other metals occupying an N,O-environment in the presence of the uranyl cation, ,, it is of note that in most cases the uranyl cation has hydrolyzed to yield more bulky SBUs that may not easily fit in the this site due to sterics.…”