Application of the Method of Molecular Voronoi–Dirichlet Polyhedra for Analysis of Noncovalent Interactions in Crystal Structures of Flufenamic Acid—The Current Record-Holder of the Number of Structurally Studied Polymorphs

Abstract

Crystal chemical analysis of eight polymorphs of flufenamic acid (FFA, C14H10NO2F3)the current record-holder of the number of structurally characterized polymorphic modificationswas carried out using the method of molecular Voronoi–Dirichlet polyhedra. It was proved that every polymorph of FFA, as every polymorph of the previous record-holder ROY (C12H9N3O2S), has a unique set of types of intra- and intermolecular noncovalent interactions.

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

“…Using the method of molecular Voronoi–Dirichlet polyhedra, we estimated the average volumes of crotonate, butyrate, and valerate ions over all the compounds in the final database, which were found to be equal to 119(8), 130(12), and 154(9) Å 3 , respectively. Thus, the lengthening of the ligand on one –CH 2 – group from a butyrate to a valerate ion results in expanding the volume of the ligand by about 24 Å 3 , which is in good agreement with the results in ref…”

Solid‐State Reactions of Eicosaborate [B20H18]2− Salts and Complexes

“…In contrast with 2g and 2h,s ingle crystalso f2a-2f and 2i were obtained from solutionsc ontaining the [iso-B 20 6 [trans-B 20 H 18 ]} 1c-2 c pair for which ar eversible single-crystal-to-single-crystal reaction occurred). [28] What is more, the volume of unit cells for 2a, 2d and 2c is % 30 3 smaller than that for their [trans-B 20 H 18 ]-containing analogs, indicatingt hat the volumeo ft he [iso-B 20 H 18 ] 2À isomer can also be smaller than the volume of [trans-B 20 H 18 ] 2À .I ndeed, average molecular Voronoi volumes of trans-a nd iso-isomers (calculated only for ordered anions at low temperatures) are equal to 382(6) and3 66(8) 3 (see references [50][51][52] for ad escription of molecular Voronoi polyhedra). It is worth noting that these values are significantly larger than the molecular volumes of disordered anions in 1a and 2a (352 and 312 3 ] 2À requires free volume.…”

Uranyl Coordination Compounds with Alkaline Earth Metals and Crotonate Ligands

“…However, taking into account their different crystal structures one might expect different motifs of noncovalent interactions, as, for example, small charged mononuclear units in compound 1 should definitely pack in a different fashion in comparison with large neutral hexanuclear clusters in compounds 3 and 4 . To study noncovalent interactions in the title compounds we used the method of molecular VD polyhedra . The results of calculations are provided in Tables S3 and S4 in Supporting Information and in Figure .…”

“…1129, 914, 1701 and 1719 Å 2 for compounds 1–4 respectively. This area represents the total surface area of all independent molecular units in the crystal structure . The decreased surface area in compound 2 in comparison with compound 1 is explained with clustering – the total surface of multiple units is larger than the surface of the same units, but aggregated in a cluster, as some former inter molecular faces become intra molecular after clustering.…”