A smorgasbord of halogen bonds?

There is an urgent need to improve our charge–density modelling capabilities for heavy atoms. A recent article opens up new opportunities in the charge–density and crystal engineering fields and in the overlap region between these fields.

The many flavours of halogen bonds – message from experimental electron density and Raman spectroscopy

The culprit is the σ-hole: short I⋯N halogen bonds do not necessarily come with high electron density in their (3,−1) critical point. The I—C geometry and Raman spectroscopy complement information from electron density.

The crystal structure of new quantum memory-storage material Sc_1.368Y_0.632SiO₅

The crystal structure of a new quantum memory-storage material, scandium yttrium oxyorthosilicate, was analyzed using single-crystal X-ray diffraction. A comparative analysis was made of the polyhedral distortion parameters and distribution features of the cations in the RE lattice sites in the mixed silicates RE1_2–xRE2_xSiO₅ (RE = Sc, Y, Lu or Tm).

Structural verification of a tetra­hydro­tetra­zole compound

Tetra­hydro­tetra­zoles are rare five-membered ring heterocycles containing four contiguous saturated N atoms. We have confirmed the assigned structure of a previously reported tetra­hydro­tetra­zole via X-ray crystallography.

A threefold superstructure of the anti-epileptic drug phenytoin sodium as a mixed methanol solvate hydrate

Phenytoin sodium crystallizes as a threefold modulated crystal structure that consists of a supercell made up of three close-to-identical repeat units.

Luminescent and magnetic bifunctional coordination com­plex based on a chiral tartaric acid derivative and europium

A new mononuclear europium com­plex incorporating the (+)-di-p-toluoyl-D-tartaric acid (D-H₂DTTA) ligand, [Eu(HDTTA)₃(CH₃OH)₃]_n, has been synthesized and characterized. Circular dichroism spectra confirmed the chirality. The complex exhibits the characteristic red emission bands associated with the Eu³⁺ ion (CIE 0.63, 0.32), with a reasonably long lifetime of 0.394 ms, indicating effective energy transfer from the ligand to the metal centre.

N-Tosyl-L-proline benzene hemisolvate: a rare example of a hydrogen-bonded carb­oxy­lic acid dimer with symmetrically disordered H atoms

A cyclic carb­oxy­lic acid dimer with disordered O—(H)⋯(H)—O hydrogen bonds is observed in the crystal structure of N-tosyl-L-proline benzene hemisolvate. An analysis of the Cambridge Structural Database revealed that only six crystal structures with a similarly disordered cyclic dimer have been recognized previously.

A novel stibium phosphate, LiBa(SbO)₂(PO₄)₃: synthesis, crystal structure and RE³⁺-activated (RE = Tb³⁺ and Eu³⁺) fluorescence performance

A novel stibium phosphate, LiBa(SbO)₂(PO₄)₃, featuring an [(SbO)₂(PO₄)₃]_∞ three-dimensional open framework, can be used as a luminescent host lattice and emits green light after doping with Tb³⁺ ions.

A sulfur coordination polymer with wide bandgap semiconductivity formed from zinc(II) and 5-methyl­sulfanyl-1,3,4-thia­diazole-2-thione

A sulfur coordination polymer constructed from Zn²⁺ ions and 5-methyl­sulfanyl-1,3,4-thia­diazole-2-thione possesses high thermal and chemical stability and a linear temperature dependence of the bandgap from room temperature to 270 °C. Further investigation revealed that the bandgap changes sharply in ammonia, but only fluctuates slightly in other solvents, indicating its promising application as a selective sensor.

A tolbutamide–metformin salt based on anti­diabetic drug combinations: synthesis, crystal structure analysis and pharmaceutical properties

A drug–drug anhydrous salt containing tolbutamide and metformin was created based on drug combinations for type 2 diabetes. Pharmaceutical property alterations were associated with the crystal packing features and potential hydrogen-bonding sites through observed changes in the crystal structures.

Niobium isocyanide com­plexes, Nb(CNAr)₆, with Ar = 2,6-di­methyl­phenyl (X­yl), a diamagnetic dimer containing four reductively coupled isocyanides, and Ar = 2,6-diiso­propyl­phenyl (Dipp), a paramagnetic monomer analogous to the highly unstable hexa­carbonyl­niobium(0)

The crystal structures of low-valent niobium isocyanide com­plexes are reported. The reaction of Nb(mesitylene)₂ with 2,6-di­methyl­phenyl isocyanide resulted in a coupling of four isocyanide ligands, two per Nb atom, to produce dimers of the general formula [Nb(CNR)_n]₂[μ-C₄(NR)₄] (n = 4, 5), where the bridging ligand is a nitro­gen (NR) analog of the squarate dianion, (C₄O₄)²⁻. The reaction with the bulkier isocyanide ligand 2,6-diiso­propyl­phenyl isocyanide resulted in Nb(CNR)₆, a rare paramagnetic monomer of formally Nb⁰.

Deciphering the hydrogen-bonding scheme in the crystal structure of tri­phenyl­methanol: a tribute to George Ferguson and co-workers

The disordered crystal structure of tri­phenyl­methanol features tetra­hedral chiral clusters formed through weak hydrogen bonds, leading to the formation of three-dimensional supra­molecular motifs having left or right handedness.

A highly efficient anti­oxidant based on boron and a Schiff base bridged phenolic di­phenyl­amine: synthesis, crystal structure and thermal and anti­oxidant properties

A new phenyl­borate derivative of a Schiff base bridged phenolic di­phenyl­amine anti­oxidant was prepared by a facile synthesis method and characterized by single-crystal X-ray diffraction. Thermogravimetric analysis and anti­oxidant activity in vegetable-based lubricant oil were studied.

A new lanthanum coordination polymer built from a semi-rigid tripodal carb­oxy­lic acid ligand: synthesis, crystal structure and properties

A new lanthanum coordination polymer was prepared by employing a semi-rigid multidentate carb­oxy­lic acid ligand. It possesses (3,6)-connected two-dimensional kgd topology sheets consistsing of secondary building units of La₂ clusters and 4,4′,4′′-{[(2,4,6-tri­methyl­benzene-1,3,5-tri­yl)tris­(methyl­ene)]tris­(­oxy)}tribenzoate ligands, which further stack into three-dimensional supra­molecular networks through π–π inter­actions.

Three new Zn^II coordination polymers constructed from a semi-rigid tri­carb­oxy­lic acid: structural changes caused by flexibility and luminescence sensing for hexa­valent chromate anions

Three new Zn^II CPs from 1D→3D with unique highly connected topologies were obtained by regulation of the flexible –CH₂–O– linker of the 5-(4-carb­oxy­benz­yloxy)isophthalic acid ligand and subtle changes of the solvent, pH and auxiliary ligands. One com­plex shows high selectivity and sensitivity for detecting hexa­valent chromate anions in aqueous solution, with a very low limit of detection of 0.434 µM for the Cr₂O₇²⁻ ion.

Structural characterization of a hybrid terpyridine–pyrazine ligand and its one-dimensional Zn^II coordination polymer: a computational approach to conventional and nonconventional inter­molecular inter­actions

The structures of a new hybrid terpyridine–pyrazine ligand, 4′-[4-(pyrazin-2-yl)phen­yl]-4,2′:6′,4′′-terpyridine (L2), and its one-dimensional coordination polymer, [Zn(acac)₂(L2)]_n (acac is acetyl­acetonate), are reported. A complete picture of the inter­molecular inter­action landscape revealed some subtle details, for example, that some weak (at first sight negligible) C—H⋯N inter­actions in the structure of free L2 play a relevant role in the crystal stabilization.

Steric and electronic evaluations of P(o-tol)R₂, where R is phenyl or cyclo­hexyl: crystal structures of SeP(o-tol)R₂

The crystal structures of SeP(o-tol)R₂, where R is phenyl or cyclo­hexyl and o-tol is ortho-tolyl, are discussed, and their electronic and steric properties evaluated using various methods.

Crystal structures and Hirshfeld surface analysis of transition-metal complexes of 1,3-azole­carb­oxy­lic acids

Through systematic variation of the heteroatom and position of the carboxyl group on 1,3-azole­carb­oxy­lic acids, their influence on supra­molecular assembly is presented through nonbonding inter­actions and Hirshfeld surface analysis.