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

Abstract

Three uranyl crotonate complexes with composition RUO2(C3H5COO)3 [R = K (I), Rb (II), Cs (III)] were studied using FT‐IR spectroscopy and X‐ray diffraction analyses. The structures of I–III are constructed of typical anionic tris(carboxylato)uranylate complexes [UO2(C3H5COO)3]–. Cubic crystals of I and II have 3D framework structure, whereas triclinic crystals of III have layered structure. In the structure of III uranyl ions are nonlinear and non equal‐arm due to uranyl‐cation UO22+–Cs+ interactions. Nonlinear optical activity of noncentrosymmetric uranyl carboxylates was estimated by second harmonic generation measurements. Uranyl crotonate complexes show about twice higher SHG ability than uranyl butyrate and valerate complexes.

Unusual Heteronuclear Uranyl Clusters with Aliphatic Monocarboxylate Ligands and Coordination Modes of Crotonate, Butyrate, and Valerate Ions

“…Assignment of absorption bands (Table ) was carried out according to refs. , , FTIR spectra of compounds with unsaturated hydrocarbon chains feature stretching and deformation vibrations of groups of atoms adjacent to C=C bonds . Very strong bands at 747 cm –1 in the spectrum of I correspond to deformation out‐of‐plane vibrations ω (=CH) and tw (=CH).…”

Crystal structures of uranyl complexes with isobutyrate and isovalerate anions

“…4 and 6). 10,16 This fact gives the highest theoretically possible number of neighbors equal to 3,6,12,24,48,96,192 and so on in the coordination spheres of R atoms in such AUO 6 frameworks. 10 Among seven listed Cs-containing compounds in Table 3, three compounds do not fit in the earlier described representation with the three-dimensional CsUO 6 frameworks.…”

“…The resulting 3D frame- work is cubic and represents the optimal ratio between the size of the pores in the CsUO 6 framework and the size of the isobutyrate ligands. 10,16,20 It is worth noting, that the structure of compound II lacks the uranyl-cation UO 2 2+ -Cs + interactions, which are frequently observed in other uranyl and cesium containing compounds, [48][49][50] but also were not observed in the analogous compound Cs[UO 2 (n-C 3 H 7 COO) 3 ] with unbranched n-butyrate ions. 16 In ref.…”

“…Two of these compounds have layered structures (see Table 3) and, thus, no three-dimensional CsUO 6 frameworks. Moreover, in the cases of compounds with acetate 53 and crotonate 48 ligands (see Table 3) the R-(O-R-) N chains bifurcate also on O atoms, but not only on R atoms (see the black and grey disks in Fig. 6), making it possible to have four neighbors in the first coordination sphere.…”

Uranyl Coordination Compounds with Alkaline Earth Metals and Crotonate Ligands

“…Up to date crystal structures of Mg, Ca, Sr and Ba uranyl crotonates are solved (compounds 1–4 respectively). As opposed to a series of uranyl crotonates with alkali metals and ammonium cation, the composition of all the four compounds 1–4 as well as their crystal structures are considerably different.…”