Syntheses, Structures, and Comparisons of Heterometallic Uranyl Iodobenzoates with Monovalent Cations

Abstract

The syntheses and crystal structures of six new heterometallic compounds containing the UO cation, o-, m-, and p-iodobenzoic acid ligands, and Tl, Rb, and Cs cations which adopt the role of both charge balancing cation and secondary metal center are described, as are the luminescent properties for Tl containing compounds 1, 4, and 6. The structures of compounds 1-3 are isomorphous and contain uranyl monomers bound by o-iodobenzoic acid ligands with Tl, Rb, and Cs cations acting as secondary metal centers. Compounds 4 and 5 are also isomorphous and feature m-iodobenzoic acid ligands bound to the uranyl cation along with Tl and Rb cations. Compound 6 is unique in this series as it is assembled from a dimeric uranyl unit and features p-iodobenzoic acid ligands and Tl cations which function as charge balancing secondary metal centers. Single crystal X-ray diffraction analysis of these materials suggests that the secondary metal cations are incorporated based on the size of their ionic radius (Tl < Rb < Cs), which is directly related to the size of the "pocket" observed in 1-6. Further, Voronoi-Dirichlet tessellation and Hirshfeld surface analysis were used to probe the coordination environment of the secondary metal centers as part of ongoing efforts to develop metrics for determining the coordination number of secondary metal cations in similar systems.

Uranyl Coordination Compounds with Alkaline Earth Metals and Crotonate Ligands

“…Being the only distinguishing feature in the syntheses of compounds 1–4 (See syntheses in Supporting Information) the M atoms serve as the driving force of formation of certain building units (mono‐, tri‐ or hexanuclear) as opposed to simply responding to a space filling opportunity in crystal structures. In that sense this work continues our studies to reveal the role of the secondary metals in the formation of bimetallic polynuclear units …”

“…As was concluded in paper in ref., Voronoi–Dirichlet (VD) tessellation with the method of intersecting spheres (MIS) are the best for studying coordination environment of metals, as well as of atoms of all other chemical elements. According to the MIS, coordination numbers (CN) of M in the title compounds are equal to 6, 7 or 8 (Table ).…”

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

“…Crystal engineering within actinide hybrid materials, in particular those incorporating hexavalent uranium, is an area of sustained interest as it has proven to be a route that allows for the rational preparation of materials with desired structures and properties. [1][2][3][4][5][6][7][8][9][10][11] This approach is predicated upon the directed assembly of tectons into crystalline architectures via attractive, noncovalent synthons, and utilization within uranyl hybrid materials has necessitated the development of a hierarchy of acceptordonor pairing preferences based on a detailed knowledge of the relationship between intra-and intermolecular interactions. 12 Recently, our group has been investigating the potential for crystal engineering to support engagement of the nominally terminal uranyl oxo groups, [13][14][15][16][17] and here we continue these efforts, employing hydrogen and halogen bonding for assembly and then describing uranyl oxo atom behavior as a synthon acceptor site.…”

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

“…Although the range of polynuclear uranyl‐based architectures is very broad, which is perfectly highlighted in a recent review, most of them are built with polytopic ligands featuring diverse coordination sites and modes. Even in the case of monotopic ligands such as halogenated benzoic acids, which at first view have only one obvious metal binding site (the carboxylate group), while the halogen sites are usually considered terminal binding sites, a great effort has been done to discover that the halogen sites can serve as supramolecular synthons or even as sites for covalent bonding in actinide systems. On the other hand, there are rare examples of compounds of uranyl ions with anions of aliphatic monocarboxylic acids L , which are constructed of large heteronuclear clusters (Figure ).…”

“…Second, there are secondary metal centers in the compounds under discussion, which are parts of the larger heterometallic clusters. In that sense, this paper may be considered as a continuation of the effort to show that, in some cases, the secondary metals (even the s‐ and p‐block metals) are not just charge‐balancing ions, but play a special structural function and drive the formation of heterometallic clusters …”