An investigation of the electron density of a Jahn–Teller-distorted Cr^II cation: the crystal structure and charge density of hexa­kis­(aceto­nitrile-κN)chromium(II) bis­(tetra­phenyl­borate) aceto­nitrile disolvate

The crystal structure of a homoleptic Cr^II complex and a study of its electron density are described. The [Cr(CH₃CN)₆]²⁺ species is a high-spin d⁴ complex with a strong static, rather than dynamic, Jahn–Teller distortion. Topological features of the electron-density distribution are explored and linked to the observed Jahn–Teller distortion.

Hirshfeld surface analysis of sulfameter (polymorph III), sulfameter dioxane monosolvate and sulfameter tetra­hydro­furan monosolvate, all at 296 K

The structures of a new polymorph of sulfameter, polymorph III, and of the dioxane and tetrahydrofuran solvates have been determined. The three structures are stabilized by strong N—H⋯N inter­molecular inter­actions which have been analysed using Hirshfeld surfaces.

Dehydration of raffinose penta­hydrate: structures of raffinose 5-, 4.433-, 4.289- and 4.127-hydrate at 93 K

In the crystal structures of raffinose N-hydrates (N is a hydration number between 4 and 5), the hydrogen-bonded chain composed of two water mol­ecules and one of the –OH groups of the galactose ring (chain A) is disordered over a similar chain composed of one water mol­ecule and the –OH group (chain A′), with an occupancy ratio of (N − 4):(5 − N). Chain A is transformed to chain A′ during the dehydration of the penta­hydrate.

The inter­play of solvation, mol­ecular conformation and supra­molecular assembly in 1,1′-({[(ethane-1,2-diyl)di­oxy](1,2-phenyl­ene)}bis­(methanylyl­idene))bis­(thio­semicarbazide) and its N,N-di­methyl­formamide disolvate

The solvent-free form and the N,N-di­methyl­formamide disolvate of a bis­(thio­semicarbazide) exhibit different inter­nal symmetries and different mol­ecular conformations, and they form different types of hydrogen-bonded sheets.

Synthesis and structures of ruthenium di- and tri­carbonyl complexes derived from 4,5-di­aza­fluoren-9-one

Two Ru^II carbonyl complexes derived from 4,5-di­aza­fluoren-9-one exhibit different modes of binding of this ligand and are of interest with regard to CO release in biological systems.

Structure and magnetic properties of a copper(II) coordination polymer based on azide, pyridine and homophthalic acid

A new coordination polymer, [Cu₂(hmph)(N₃)₂(py)₂]_n (hmph is homophthalate and py is pyridine), was synthesized and characterized as having a one-dimensional chain structure composed of tetra­nuclear Cu^II units containing (μ_1,1-N₃⁻)(μ-syn–syn-COO⁻)₂ and (μ_1,1-N₃⁻)₂ bridges, and exhibits dominant anti­ferromagnetic behaviour.

Two new isatin derivatives: 1-benzyl-4,5,6-trimeth­oxyindoline-2,3-dione and 1-benzyl-5-fluoro­indoline-2,3-dione

In two isatin (1H-indole-2,3-dione) compounds, the ring systems are planar and the bicyclic scaffolds are almost superimposable. Both crystal structures are stabilized by C—H⋯O inter­actions.

Two different one-dimensional Cd^II halide coordination polymers constructed through bridging carboxyl­ate ligands

In order to explore new metal coordination polymers and to search for new types of ferroelectrics among hybrid coordination polymers, the use of the 4-(di­methyl­amino)­pyridin-1-ium-1-acetate anion and the 1-cyano­methyl-1,4-diazoniabi­cyclo­[2.2.2]octane dication as templates for the formation of two different cadmium(II) coordination polymers was investigated.

Supra­molecular hydrogen-bonding patterns in two cocrystals of the N(7)–H tautomeric form of N⁶-benzoyl­adenine: N⁶-benzoyl­adenine–3-hy­droxy­pyridinium-2-carboxyl­ate (1/1) and N⁶-benzoyl­adenine–DL-tartaric acid (1/1)

In two novel cocrystals of the N(7)—H tautomeric form of N⁶-benzoyl­adenine (BA), i.e. with 3-hy­droxy­pyridinium-2-carboxyl­ate (3HPA) and DL-tartaric acid (TA), the BA Watson–Crick face inter­acts with the 3-HPA mol­ecule in the former, while the BA Hoogsteen face inter­acts with the TA mol­ecule in the latter. Typical inter- and intra­molecular hydrogen-bonding and stacking inter­actions are observed in both crystal structures.

Halogen bonds on demand: I⋯S contacts in cocrystals of trans-bis­(thio­cyanato-κN)tetra­kis­(4-vinyl­pyridine-κN)nickel(II) and 2,3,5,6-tetra­fluoro-1,4-di­iodo­benzene

A short S⋯I halogen bond occurs in the cocrystal formed by di­thio­cyanato­tetra­kis­(4-vinyl­pyridine)­nickel(II) and 2,3,5,6-tetra­fluoro-1,4-di­iodo­benzene. Such halogen bonds to sulfur are significantly less common than to smaller electronegative atoms.

The new structure type Gd₃Ni₇Al₁₄

The crystal structure of the inter­metallic compound Gd₃Ni₇Al₁₄ belongs to a family of two-layer structures and can be described as an assembly of inter­penetrating centred straight prisms. The close relationship with PrNi₂Al and ZrNiAl is discussed.

Structural consequences of weak inter­actions in di­spiro­oxindole derivatives

Weak inter­actions play a prominent role in the structural stability of di­spiro­oxo­indoles and contribute to their highly regio- and diastereoselective synthesis.

Crystal structures of the pyrazinamide–p-amino­benzoic acid (1/1) cocrystal and the transamidation reaction product 4-(pyrazine-2-carboxamido)­benzoic acid in the molten state

The 1:1 pharmaceutical cocrystal of the anti­tuberculosis drug pyrazinamide (PZA) and p-amino­benzoic acid (p-ABA) has been prepared and thoroughly characterized using relevant solid-state characterization methods. Inter­estingly, the components of the cocrystal reacted in the molten state to give the corresponding carboxamide with the release of ammonia. Both crystal structures are governed by coventional O—H⋯O, N—H⋯O and N—H⋯N hydrogen-bonding inter­actions.

A new one-dimensional Zn^II coordination polymer based on 2-[(1H-imidazol-1-yl)methyl]-1H-benz­imidazole and benzene-1,2-di­carboxyl­ate

In a new zinc(II) coordination polymer based on multidentate N-donor 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole (imb) and bridging O-donor benzene-1,2-di­carboxyl­ate (bdic²⁻) ligands, binuclear [(Zn)₂(imb)₂] units are connected alternately by pairs of bridging bdic²⁻ ligands, yielding an infinite one-dimensional chain.

Crystallographic identification of an unexpected by-product in an Ullman's reaction toward bi­phenyls: 1-(4-hex­yloxy-3-hy­droxy­phen­yl)ethanone

Single-crystal crystallographic analysis allowed the identification of an unexpected rearranged by-product of an Ullmann reaction as 1-(4-hex­yloxy-3-hy­droxy­phen­yl)ethanone and a possible mechanism for its formation is suggested.

(5RS)-6H-Spiro­[pyrazolo­[1,5-c]quinazoline-5,4′-thio­chroman]: efficient synthesis under mild conditions, mol­ecular structure and supra­molecular assembly

In a spiro­[pyrazolo­[1,5-c]quinazoline-5,4′-thio­chroman], prepared under very mild reaction conditions, the two nonplanar heterocyclic rings show different conformations. Hydrogen bonds of the N—H⋯S and C—H⋯π(arene) types link the mol­ecules into complex sheets.