Geometry variation of complex ions in crystals †

On the nature of tetraalkylammonium ions in common electrochemical solvents: General and specific solvation – Quantitative aspects

“…Similar effects of increasing stabilization as the number of solvent molecules increase up to a maximum are found with inorganic ions [12,38,40]. X-ray crystallographic data [8][9][10] and our earlier computational study [2] agree that lithium coordinates to four solvent molecules in THF. Table 2 presents only the data for the tetrasolvated ions, since these are the dominant species in all cases in which specific solvation is operative.…”

“…Although many hydrated metal ions are known, specific solvation is not limited to water. For example, X-ray crystallographic analyses of lithium compounds crystallized from tetrahydrofuran (THF) show the presence of four THF molecules tetrahedrally distributed around lithium, with the oxygen atom of each THF molecule directed toward the central lithium ion [8][9][10]. Lithium ion has also been found to be specifically solvated by four acetone [11], dimethylsulfoxide [12], and acetonitrile [13] molecules.…”

Does Hydrogen Bonding Matter in Crystal Engineering? Crystal Structures of Salts of Isomeric Ions

“…We have addressed the problem by preparation and analysis of a series of crystal structures of the [ [12] while the [SbCl 5 ] 2À ion (G) is much more variable in geometry and is usually self-associated through secondary Sb¥¥¥Cl interactions forming dimers (H), tetramers (I) or polymers such as J. [13] Valdÿs-MartÌnez et al have reported a related study in which they studied the structures of salts of non-isomeric cations without strong hydrogenbond-donor capability with anions based on copper and zinc.…”

Synthesis of Sb2Se3 and Bi2Se3 Nanoparticles in Ionic Liquids at Low Temperatures and Solid State Structure of [C4C1Im]3[BiCl6]

“…The hexachlorobismuthate(III) anion, a 14e system in which the electron lone pair formally shows a high (formally stereochemically inactive) s‐character, often shows high variations (σ) in the Bi–Cl bond lengths and Cl–Bi–Cl angles. The distortion of the octahedral coordination of the [BiCl 6 ] 3– anion has been traditionally explained as accommodating the spatial requirements of the electron lone pair, which points away from the shortest Bi–Cl bonds in the octahedron, while more recent studies addressed the distortion to the softness of this specific anion . In addition, the variations can be significantly enhanced in case of the presence of intermolecular (weak) hydrogen bonding.…”

“…The distortion of the octahedral coordination of the [BiCl 6 ] 3anion has been traditionally explained as accommodating the spatial requirements of the electron lone pair, which points away from the shortest Bi-Cl bonds in the octahedron, while more recent studies addressed the distortion to the softness of this specific anion. [32] In addition, the variations can be significantly enhanced in case of the presence of intermolecular (weak) hydrogen bonding. [30c] Orgel attributed the structural distortion by mixing of the s and p orbital of the cation, [33a] which was confirmed by Wheeler and Kumar using extended Hückel calculations, according to which the trigonal distortion in the molecular anion [BiCl 6 ] 3results from the mixing of the cationic s orbital (HOMO) and the cationic p z orbital (LUMO).…”