Comparison of the hydrogen-bond patterns in 2-amino-1,3,4-thia­diazol­ium hydrogen oxalate, 2-amino-1,3,4-thia­diazole–succinic acid (1/2), 2-amino-1,3,4-thia­diazole–glutaric acid (1/1) and 2-amino-1,3,4-thia­diazole–adipic acid (1/1)

In 2-amino-1,3,4-thiadiazolium hydrogen oxalate, 2-amino-1,3,4-thiadiazole–glutaric acid (1/1) and 2-amino-1,3,4-thiadiazole–adipic acid (1/1), the graph-set motifs (8), with N—H⋯O and O—H⋯N hydrogen bonds of moderate strength, are the most prominent features (N—H⋯O hydrogen bonds are present only in 2-amino-1,3,4-thiadiazolium hydrogen oxalate). The hydrogen-bond pattern of 2-amino-1,3,4-thiadiazole–succinic acid (1/2) differs considerably from the other title structures, though N—H⋯O and O—H⋯N hydrogen bonds of moderate strength are also present. There are nonbonding S⋯O interactions in all four structures, however, the packing patterns are quite different.

The three-dimensional coordination polymer poly[[aqua­[μ₄-2,2′-(diazene-1,2-di­yl)dibenzoato]lead(II)] 1,2-bis­(pyridin-4-yl)ethyl­ene hemisolvate]

A three-dimensional coordination polymer was synthesized by hydro­thermal reaction of Pb(OAc)₂·3H₂O (OAc is acetate), 2,2′-(diazene-1,2-di­yl)dibenzoic acid (H₂L) and 1,2-bis­(pyridin-4-yl)ethyl­ene (bpe), displaying a 4¹²6³ topology network in which bpe mol­ecules act as noncoordinating guests. Inter­molecular hydrogen bonds and π–π stacking inter­actions further strengthen the three-dimensional framework.

Monomolecular sheets of propeller-shaped tri­ethyl 4,4′,4′′-[benzene-1,3,5-triyltris(ethyne-2,1-di­yl)]tribenzoate deutero­chloroform monosolvate

Triethyl 4,4′,4′′-[benzene-1,3,5-triyltris(ethyne-2,1-di­yl)]tribenzoate is a propeller-shaped mol­ecule of particular inter­est in the field of metal–organic frameworks (MOFs), where its hydrolyzed analogue forms MOF structures with high surface areas. Centrosymmetric dimers formed by π–π inter­actions are inter­connected by inter­molecular C—H⋯π inter­actions.

Two precatalysts for application in asymmetric homogeneous hydrogen­ation

The structures of two BICP complexes of rhodium(I) show a strong deviation in their backbones from the expected skew conformation. These compounds are applied as precatalysts in asymmetric homogeneous hydrogenation.

Synthesis and crystal structures of RE₇Zn_21+xSi_2–x [RE = Ce, Pr, and Nd; 0.09 (1) < x < 0.95 (1)]

The structures of the ternary compounds RE₇Zn_21+xSi_2−x [RE = Ce, Pr, and Nd; 0.09 (1) < x < 0.95 (1)] are reported. Important structural features in these compounds are the large polyhedral cages made up of Zn atoms and the Si atoms in trigonal planar coordination. A small occupational Zn–Si disorder is found at the Si site.

Glycyl-L-alanine: a multi-temperature neutron study

Neutron diffraction data have been collected at 12, 50, 150 and 295 K for the dipeptide glycyl-L-alanine in order to obtain accurate positional and anisotropic displacement parameters for the H atoms. The values of these parameters serve as a benchmark for assessing the equivalent parameters obtained from a so-called Hirshfeld-atom refinement of X-ray diffraction data.

Three closely-related cyclo­hexa­nols (C₃₅H₂₇X₂N₃O₃; X = F, Cl or Br): similar mol­ecular structures but different crystal structures

Three highly substituted cyclo­hexa­nols were prepared in satisfactory yield and with good stereospecificity by reaction of 4-halogenobenzaldehydes with 2-acetyl­pyridine under mild conditions. The mol­ecular structures of the cyclo­hexa­nols are very similar, but the crystal structures, particularly the space groups and the supra­molecular assemblies, are all different.

Three p-xylene-solvated pseudo­polymorphs of bis­[1,3-bis­(penta­fluoro­phen­yl)propane-1,3-dionato]copper(II)

In three differently solvated Cu²⁺ complexes of 1,3-bis­(penta­fluoro­phen­yl)propane-1,3-dionate, the p-xylene solvent mol­ecules are involved in arene–perfluoro­arene inter­actions with the penta­fluoro­phenyl groups. In a tetra­solvate, two of the p-xylene mol­ecules are located on the coordination CuO₄ plane forming a uniform cavity produced by metal⋯π inter­actions.

NMR analysis of a series of 1,2-bis­(1-R-5-oxo-2,3-di­hydro-1H-pyrrol-4-yl­idene)ethanes and X-ray crystal structure analysis of the R = mesityl compound

The structures and chemical properties of a new class of conjugated buta-1,3-dienes were studied by NMR, MS, X-ray analysis and quantum chemical calculations. The compounds can be used as dyes and pigments due to their long-range conjugated systems.

The polyocta­hedral silsesquioxane (POSS) 1,3,5,7,9,11,13,15-octa­phenyl­penta­cyclo­[9.5.1.1^3,9.1^5,15.1^7,13]octa­siloxane (octa­phenyl-POSS)

Solvent-free single crystals of octa­phenyl-POSS were obtained by dehydration/condensation of the tetrol Si₄O₄(Ph)₄(OH)₄. The powder pattern matches well with the experimentally measured powder pattern of commercial octa­phenyl-POSS. The geometry of the crystal is compared with that in the gas phase, and has shorter Si—O bond lengths and a broader range of Si—O—Si bond angles.

Two organo­phospho­rus pesticides: methyl para­thion and dicapthon

The structures of methyl para­thion and its 2-chloro derivative, dicapthon, are observed to have a few dissimilar features. These are notably around the C atoms to which the thio­phosphate and nitro groups are attached and those involving the phenolic O versus the –OMe groups.

The topotactic dehydration of monoclinic {[Co(pht)(bpy)(H₂O)₂]·2H₂O}_n into ortho­rhom­bic [Co(pht)(bpy)(H₂O)₂]_n (pht is phthalate and bpy is 4,4′-bi­pyridine)

{[Co(pht)(bpy)(H₂O)₂]·2H₂O}_n (P2/n) single crystals (where pht is phthalate and bpy is 4,4′-bi­pyridine) dehydrate in a topotactic fashion into an anhydrate formulated as [Co(pht)(bpy)(H₂O)₂]_n, which organizes in the ortho­rhom­bic system (Pmn2₁) in a disordered fashion, where two mirror-related 0.50:0.50 occupancy two-dimensional planar substructures are mirrored in a plane perpendicular to [100]. These two-dimensional substructures are also present in the parent hydrate, and have been found in topologically related structures with different anions and cations.

A pillared framework coordination polymer based on the Cd₃(μ₃-OH) unit: poly[[(μ₄-5-amino­tetra­zolato-κ⁴N¹:N²:N³:N⁴)chlorido-μ₃-hydrox­ido-(μ₃-isonicotinato-κ³N:O:O′)­dicadmium(II)] 0.14-hydrate]

In a pillared three-dimensional Cd^II coordination polymer incorporating isonicotinate, 5-aminotetrazolate, chloride and hydroxide ligands, Cd₃(μ₃-OH) units are laced around with a belt of chloride ligands. The belts are further connected into undulating layers via weak inter-belt Cd—Cl bonds.

Substituent effects in nitro derivatives of carbazoles investigated by comparison of low-temperature crystallographic studies with density functional theory (DFT) calculations

The crystal and mol­ecular structures of substituted carbazoles with π-electron-withdrawing –NO₂ groups are reported, and the effects of these substituents on the aromaticity of the arene and pyrrole rings are assessed by means of HOMA indices. Density functional theory (DFT) calculations were performed to analyse the differences in the geometries of the studied compounds between the crystalline state and isolated mol­ecules.

One- and two-dimensional Cd^II coordination polymers constructed from 2-(2-methyl-1H-benzimidazol-1-yl)acetate ligands

The one- and two-dimensional polymorphic cadmium polycarboxyl­ate coordination polymers catena-poly[bis[μ₂-2-(2-methyl-1H-benzimidazol-1-yl)acetato]cadmium(II)] and poly[bis[μ₂-2-(2-methyl-1H-benzimidazol-1-yl)acetato]cadmium(II)] were prepared under similar solvothermal conditions. Alternating layers of chains in the former are perpendicular to one another, while the latter contains (4,4)-connected nodes yielding square-grid layers.

Three new phospho­ric tri­amides with a [C(O)NH]P(O)[N(C)(C)]₂ skeleton: a database analysis of C—N—C and P—N—C bond angles

The crystal structures of three new phospho­ric tri­amides with a [C(O)NH]P(O)[N(C)(C)]₂ skeleton are discussed. The C—N—C and P—N—C bond angles in these structures and analogous structures deposited in the Cambridge Structural Database are analysed.