Cation-cation interactions between uranyl(VI) ions

Synthesis, Structure, and Nonlinear Optical Activity of K, Rb, and Cs Tris(crotonato)uranylates(VI)

“…Such oxo ligand functionalization was unique for a period of time, but today the number of examples has significantly increased 10. Accordingly,10 the UO 2 2+ –Cs + interaction should be referred as “uranyl–cation” interaction as opposed to “cation–cation” interaction, which historically describe interaction of oxygen atom of uranyl (in general, actinyl) ion with another uranyl ion 11. Such “uranyl–cation” interactions in the structure of III may be the reason of a distorted arrangement of uranyl ions: deviation from linearity is about 2°, and the difference in length of the two U=O bonds reaches 0.04 Å (Table 2).…”

Dissecting the cation–cation interaction between two uranyl units

“…1,2 The [UO 2 ] 2+ building block features short U-O bond lengths (ca. [8][9][10][11][12][13][14][15][16][17][18] Despite its unique characteristics, experimental identification of the [UO 2 ] 2+ unit is often hampered by the coordination of another uranyl ''yl'' oxygen to the actinyl centre. Since the symmetric stretching frequency n 1 (S g + ) in uranyl(VI) is IR-forbidden, in asymmetric surroundings it has a weak absorption signal in the range of 800 to 900 cm À1 .…”

“…The asymmetric stretching frequency n 3 (S u + ), on the other hand, is IR-allowed and typically experimentally observable in the range of 900 to 1050 cm À1 . 18,23,24 Since the inter-molecular bond formed by the CCIs is longer than the intra-molecular U-O bonds of the uranyl cation in the majority of compounds, it can be considered as a ''weak unit'' in the supra-molecular structure. [3][4][5][6][7] Furthermore, uranyl(VI) features a distinctive electron absorption spectrum (sf and sd) in the range of 2.2 to 3.2 eV (400-550 nm).…”

“…19 Such interactions are commonly referred to as cation-cation interactions (CCIs). While there is abundant experimental data for CCIs between uranyl cations, 18 ] 2+ ) using present-day state-of-the-art quantum chemistry methods. This clustering might facilitate structural changes and alter the spectroscopical properties of the bare [UO 2 ] 2+ moiety.…”

Unusual Heterometallic Cation‐Cation Interactions in Uranyl Zinc Germanates

“…These interactions are dominant in the solid‐state and solution chemistry of pentavalent neptunyl ion and can also occur in other An V complexes including U V , Pu V , and Am V . CCIs are relatively rare in U VI species owing to the lower negative charge of the oxo groups in the hexavalent uranyl cation, but this class of compounds is expanding as growing numbers of new U VI compounds have been synthesized . Heterometallic CCIs between uranyl cations and alkaline or alkaline‐earth metal ions metal have also been identified in a few complexes, e.g.…”