Charge‐Assisted Hydrogen‐Bonding and Crystallization Effects within U^VI Glycine Compounds

Abstract

U VI chemistry is dominated by the uranyl (UO 2 ) 2+ cation, in which the oxo group is essentially passivated by a triple bond to the metal center. Weak interactions between the oxo group Lewis acids or hydrogen-bond donors can be observed in extended solids, but there is little understanding of how the uranyl bond is affected by these additional forces. In the current study, the influence of charge-assisted hydrogen-bonding and crystallization effects on the uranyl oxo bond is explored through the synthesis and characterization of four uranyl compounds: [(UO 2 ) 3 (Gly) 2 (O) 2 (OH) 2 ](H 2 O) 1.5 (UG1b), [(UO 2 ) 4 (Gly) 3 -(For)(O) 3 (OH)](H 2 O) 6.5 (UGFA1a), [(UO 2 ) 8 (Gly) 6 (For) 2 (O) 6 (OH) 2 ]-(H 2 O) 10 (UGFA1b), and [(UO 2 ) 4 (Gly) 3 (O) 3 (OH) 2 ](HFor)(H 2 O) 9.45 [a]where S is representative of the bond valence or bond flux of each bond (expressed as valence units), R is the bond distance, R 0 is the Eur.

Detection and identification of solids, surfaces, and solutions of uranium using vibrational spectroscopy

“…McGlynn et al [145] and Bartlett and Cooney [63] first reported a range of force constants for uranyl compounds and more recently, Schnaars and Wilson [125,146] utilized force constants within uranyl tetrachloride complexes to understand slight differences in bond strength. Force constants have also been used to evaluate subtle differences in intermolecular interactions within carboxylate complexes and to assess the impact of charge-assisted hydrogen bonding within uranyl glycine compounds [147]. Previously, the lowest k f value for isolated uranyl complexes was reported for K 3 UO 2 F 5 at 6.03 mdyn/Å [63], although a majority of the values were observed between 6.4 and 7.5 mdyn/Å.…”

Probing hydrogen and halogen-oxo interactions in uranyl coordination polymers: a combined crystallographic and computational study

“…The uranyl cation is known to feature three characteristic vibrational modes: a symmetric stretching mode (1, 860-880 cm -1 , Raman active), a bending mode (2, 200-210 cm -1 , infrared active), and an asymmetric stretching mode (3, 930-960 cm -1 , infrared active), [48][49][50] and the frequencies of these vibrational modes, in particular 1 and 3, provide valuable spectroscopic information about relative strengths of U=O bonds (which are affected by halogen-oxo interactions). 16,17,27 A look at the Raman and IR spectra of compounds 3 and 4 reveals redshifts (6 cm -1 in the Raman and 11 cm -1 in the IR) with respect to the miodo compound (4) when comparing to the m-bromo compound (3) ( Figure 6). These findings qualitatively illustrate that the iodo-oxo interaction in 4 has a greater effect on the uranyl oxo group, and also suggest that the oxo interactions in 3 and 4 may not be of 'equivalent strength', as suggested by crystallography.…”

“…16 Herein we expand our efforts in this arena and use four uranyl hybrid materials (two novel and two known) that feature benzoic acid ligands with systematically varied meta-substituents (benzoic acid (1), m-chloro- (2), m-bromo- (3), and m-iodobenzoic acid (4)) to probe the value and limits of this crystallographic metric. Uranyl oxo atom participation in bonding via 'oxo-functionalization' is a growing area of research, [22][23][24][25][26] whereas oxo engagement in hydrogen and halogen bonding synthons remains underexplored, 6,27 particularly within simple coordination chemistry, with successful efforts often requiring a dual ligand strategy wherein strongly electron donating N-donor ligands in the equatorial plane are paired with benzoic acid linkers featuring polarizable halogen atoms at their periphery to facilitate halogen bonding interactions. 14,16 Compounds 1-4 all lack an equatorial electron donating species, yet feature either hydrogen or halogen bonding with the uranyl oxo atoms, and the syntheses, crystal structures, and modes of supramolecular assembly are reported for all four materials.…”

Pseudohalide Tectons within the Coordination Sphere of the Uranyl Ion: Experimental and Theoretical Study of C–H···O, C–H···S, and Chalcogenide Noncovalent Interactions

“…The force constants do not change significantly from this value ( n BuS, k1 = 6.92 mdyn/Å; range = 6.84 -7.06 mdyn/Å) and there is no correlation to the donor … acceptor bond distances (Table S15) so the hydrogen bonding does not influence these metrics, as observed by others. 22 There is however a larger k1 and k12 associated with the NCSe ligands compared to the NCS analogues as shown for the n PrS/ n PrSe (S: k1 = 6.91 mdyn/Å, k12 = -0.14 mdyn/Å; Se: k1 = 6.98 mdyn/Å, k12 = -0.14 mdyn/Å) and Et3NBzS/Et3NBzSe (S: k1 = 6.78 mdyn/Å, k12 = -0.10 mdyn/Å; Se: k1 = 6.86 mdyn/Å, k12 = -0.17 mdyn/Å) families. The structural information showed no significant changes in donor … acceptor bond lengths, so this could be a manifestation of the differing donor abilities of the coordinating ligands.…”