Cover illustration: Recent developments in SHELXL facilitate refinement against neutron diffraction data, the treatment of H atoms, the determination of absolute structure, the input of partial structure factors and the refinement of twinned and disordered structures. The new features added to the refinement program SHELXL since 2008 are described and explained. See Sheldrick [Acta Cryst. (2015), C71, 3-8].
The SQUEEZE tool in the PLATON program is described. Using an iterated back-Fourier transform, it determines the contribution of a disordered solvent or ion to the calculated structure factors. The routine is discussed in the context of structure refinement with SHELXL.
3-Cyano-6-hydroxy-4-methyl-2-pyridone (CMP) has been cocrystallized with 2,6-dichlorophenol, 4-amino-2-chloro-6-methylpyrimidine and 2-chloro-4,6-diamino-1,3,5-triazine in N,N-dimethylacetamide, N,N-dimethylformamide and dimethyl sulfoxide, leading to two pseudopolymorphs of CMP and two cocrystals containing CMP and their nucleophilic aromatic substituted coformers.
The B atom in four (2,2′-bipyridyl)(ferrocenyl)boronium derivatives has a distorted tetrahedral coordination. The B—N(amine) bonds are shortened by delocalization of π-electrons from the N to the B atom. The B—N(bipyridyl) bonds are longer in the cations with an amine substituent than in the cations with a methylene C atom bonded to boron.
The name `bath salts', for an emerging class of synthetic cathinones, is derived from an attempt to evade prosecution and law enforcement. The structures of five salts of MDPV (3,4-methylenedioxypyrovalerone) or ethylone are described, together with the serendipitous discovery of a new example of the H2O–H3O+–H2O form of the H7O3+ cation.
Li2B2C crystallizes as a new structure type and consists of structural fragments which are typical for structures of elemental lithium and boron or binary borocarbide B13C2. Electronic structure calculations using the TB–LMTO–ASA method show strong B⋯C and B⋯B interactions.
In a novel two-dimensional coordination polymer, phthalate ligands connect neighbouring CuII cations into an infinite one-dimensional chain. Adjacent one-dimensional chains are connected by naphthalene-1,4-dicarboxamide ligands, forming an intriguing two-dimensional framework. The magnetic properties and thermal stability of this complex are also described.
Two organic–inorganic hybrid compounds have been prepared by the combination of the 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium cation and perhalometallate [CoCl4]2− and [ZnCl4]2− anions. The cationic and anionic species are linked mainly through N—H⋯Cl and C—H⋯Cl hydrogen bonds and π–π contacts to form a three-dimensional hydrogen-bonded network.
The crystal structures of two substituted pyrazole derivatives are stabilized by the presence of C—H⋯O, C—H⋯π and π–π weak intermolecular interactions, and also by uncommon trifurcated C—Cl⋯Cl—C interactions that are discussed in detail.
Two racemic 4-aryl-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate esters were prepared from simple precursors in a one-pot cyclocondensation reaction. The molecules are linked into different types of ribbon by a combination of N—H⋯O and N—H⋯S hydrogen bonds.
Ethyltriphenylphosphonium (EtPh3P+) cations fill voids in a three-dimensional anionic cadmium dicyanamide network. Each CdII atom is connected to six neighbouring CdII atoms through six separate dicyanamide ligands, forming cube-shaped cages. The three-dimensional anionic network encloses a solvent-accessible void space of 1851 Å3, amounting to 69.3% of the unit-cell volume.
In 1-phenylindolin-2-one (Pbca), (I), 5-bromo-1-phenylindolin-2-one (P21/c), (II), and 5-iodo-1-phenylindolin-2-one (Aea2), (III), density functional theory (DFT) calculations show that the molecular dipole moment gradually decreases in the order (I) > (II) > (III). The relatively smaller dipole moment of (III) and the larger non-electrostatic intermolecular interactions may be the main reasons for the noncentrosymmetric and polar structure of (III).
Two supramolecular complexes of the antibiotic trimethoprim with glutarimide and its 3,3-dimethyl derivative are held together by three hydrogen bonds between the pyrimidine ring and the imide group. In both structures, the heterodimers and their constituents show similar conformations and hydrogen-bonding patterns, and also the crystal packings show similarities with an extended network of hydrogen bonds.
The crystal structure of the synthetic compound Ca3ZnGeO2[Ge4O12] was determined from single-crystal X-ray diffraction data and the close relationship of its structure to taikanite is revealed and discussed.