Crystal structure of a trigonal polymorph of aquadioxidobis(pentane-2,4-dionato-κ2 O,O′)uranium(VI)

The title compound, [UO2(acac)2(H2O)] consists of a uranyl(VI) unit ([O=U=O]2+) coordinated to two monoanionic acetylacetonate (acac, C5H7O2) ligands and one water molecule. The asymmetric unit includes a one-half of a uranium atom, one oxido ion, one-half of a water molecule and one acac ligand. The coordination about the uranium atom is distorted pentagonal–bipyramidal. The acac ligands and Ow atom comprise the equatorial plane, while the uranyl O atoms occupy the axial positions. Intermolecular hydrogen bonding between complexes results in the formation of two-dimensional hexagonal void channels along the c-axis direction with a diameter of 6.7 Å. The monoclinic (P21/c space group) polymorph was reported by Alcock & Flanders [(1987). Acta Cryst. C43, 1480–1483].

anti-1-(Benzylamino)glyoxime. Corrigendum

In the paper by Köysal et al. [Acta Cryst. (2004), E60, o515–o516], there was an error in the name of the last author.

A new three-dimensional twofold interpenetrated cadmium(II) metal–organic framework: synthesis, structure and photoluminescence properties. Corrigendum

In the article by Zhang & Wang [Acta Cryst. (2021), C77, 691–697], the topology of the title compound is corrected.

A second solvatomorph of poly[[μ4-N,N′-(1,3,5-oxadiazinane-3,5-diyl)bis(carbamoylmethanoato)]nickel(II)dipotassium]: crystal structure, Hirshfeld surface analysis and semi-empirical geometry optimization

The title compound, poly[triaquabis[μ4-N,N′-(1,3,5-oxadiazinane-3,5-diyl)bis(carbamoylmethanoato)]dinickel(II)tetrapotassium], [K4Ni2(C7H6N4O7)2(H2O)3] n , is a second solvatomorph of poly[(μ4-N,N′-(1,3,5-oxadiazinane-3,5-diyl)bis(carbamoylmethanoato)nickel(II)dipotassium] reported previously [Plutenko et al. (2021). Acta Cryst. E77, 298–304]. The asymmetric unit of the title compound includes two structurally independent complex anions [Ni(C7H6N4O7)]2−, which exhibit an L-shaped geometry and consist of two almost flat fragments perpendicular to one another: the 1,3,5-oxadiazinane fragment and the fragment including other atoms of the anion. The central Ni atom is in a square-planar N2O2 coordination arrangement formed by two amide N and two carboxylate O atoms. In the crystal, the title compound forms a layered structure in which layers of negatively charged complex anions and positively charged potassium cations are stacked along the a-axis direction. The polymeric framework is stabilized by a system of hydrogen-bonding interactions in which the water molecules act as donors and the carboxylic, amide and water O atoms act as acceptors.

Single crystals of SnTe3O8 in the millimetre range grown by chemical vapor transport reactions

Tin(IV) trioxidotellurate(IV), SnTe3O8, is a member of the isotypic M IVTeIV 3O8 (M = Ti, Zr, Hf, Sn) series crystallizing with eight formula units per unit cell in space group Ia\overline{3}. In comparison with the previous crystal structure model of SnTe3O8 based on powder X-ray diffraction data [Meunier & Galy (1971). Acta Cryst. B27, 602–608], the current model based on single-crystal X-ray data is improved in terms of precision and accuracy. Nearly regular [SnO6] octahedra (Sn site symmetry .\overline{3}.) are situated in the voids of an oxidotellurate(IV) framework built up by corner-sharing [TeO4] bisphenoids (Te site symmetry 2..). A quantitative structural comparison revealed a very high degree of similarity for the structures with M = Ti, Zr, Sn in the M IVTe3O8 series.

Low-temperature phases of dicalcium barium hexakis(propanoate)

The structure determinations of phases (II) and (III) of barium dicalcium hexakis(propanoate) {or poly[hexa-μ4-propanoato-bariumdicalcium], [BaCa2(C3H5O2)6] n } are reported at 240 and 130 K, respectively [phase (I) was determined previously by Stadnicka & Glazer (1980). Acta Cryst. B36, 2977–2985; our structure determination of phase (I) at room temperature is included in the supporting information]. In the high-temperature phase, the Ba2+ cation is surrounded by six carboxylate groups in bidentate bridging modes. In the low-temperature phases, five carboxylate groups act in bidentate bridging modes and one acts in a monodentate bridging mode around Ba2+. The Ca2+ cations are surrounded by six carboxylate O atoms in a trigonal antiprism in all the structures. The Ba2+ and Ca2+ cations are underbonded and significantly overbonded, respectively, in all the phases. The bonding of the Ba2+ cation increases slightly at the cost of the bonding of Ca2+ cations during cooling to the low-temperature phases. The phase transitions during cooling are accompanied by ordering of the ethyl chains. In room-temperature phase (I), all six ethyl chains are positionally disordered over two positions in the crossed mode, with additional splitting of the ethyl α- and β-C atoms. In phase (II), on the other hand, there are three disordered ethyl chains, one with positionally disordered ethyl α- and β-C atoms, and the other two with positionally disordered ethyl β-C atoms only, and in the lowest-temperature phase (III) there are four ordered ethyl chains and two disordered ethyl chains with positionally disordered ethyl β-C atoms only.

Analytical description of nanowires. I. Regular cross sections for zincblende and diamond structures. Corrigendum

In the paper by König & Smith [Acta Cryst. (2019), B75, 788–802], several equations had minor errors in their coefficients defining characteristic lengths and area of zinc-blende nanowire cross sections, thereby deviating from the exact analytical solution by 1.4 ± 0.8 %. A fully corrected version of the paper is provided.

A rush to explore protein–ligand electrostatic interaction energy with Charger

The mutual penetration of electron densities between two interacting molecules complicates the computation of an accurate electrostatic interaction energy based on a pseudo-atom representation of electron densities. The numerical exact potential and multipole moment (nEP/MM) method is time-consuming since it performs a 3D integration to obtain the electrostatic energy at short interaction distances. Nguyen et al. [(2018), Acta Cryst. A74, 524–536] recently reported a fully analytical computation of the electrostatic interaction energy (aEP/MM). This method performs much faster than nEP/MM (up to two orders of magnitude) and remains highly accurate. A new program library, Charger, contains an implementation of the aEP/MM method. Charger has been incorporated into the MoProViewer software. Benchmark tests on a series of small molecules containing only C, H, N and O atoms show the efficiency of Charger in terms of execution time and accuracy. Charger is also powerful in a study of electrostatic symbiosis between a protein and a ligand. It determines reliable protein–ligand interaction energies even when both contain S atoms. It easily estimates the individual contribution of every residue to the total protein–ligand electrostatic binding energy. Glutathione transferase (GST) in complex with a benzophenone ligand was studied due to the availability of both structural and thermodynamic data. The resulting analysis highlights not only the residues that stabilize the ligand but also those that hinder ligand binding from an electrostatic point of view. This offers new perspectives in the search for mutations to improve the interaction between the two partners. A proposed mutation would improve ligand binding to GST by removing an electrostatic obstacle, rather than by the traditional increase in the number of favourable contacts.

A new guaninate hydrate K+·C5H4N5O−·H2O: crystal structure from 100 to 300 K in a comparison with 2Na+·C5H3N5O2−·7H2O

A new guanine salt hydrate, K+·C5H4N5O−·H2O, was obtained and characterized by single-crystal X-ray diffraction in the temperature range 100 K–300 K and compared with that of the previously documented sodium salt hydrate (2Na+·C5H3N5O2−·7H2O) [Gur & Shimon (2015). Acta Cryst. E71, 281–283; Gaydamaka et al. (2019). CrystEngComm, 21, 4484–4492]. Both sodium and potassium salt hydrates have channels. However, the structure of the channels, the cation coordination, the protonation (and, respectively, the charge) of the guanine anions, as well as the role of water molecules in the crystal structure are different for the two salt hydrates. In the crystal structures of the potassium salt, the guanine anions are linked via hydrogen bonds into quartets that form open cylindrical channels in a honeycomb framework. Water molecules `line the walls' of the channels, whereas the potassium cations fill the intra-channel space. This contrasts with the structure of the sodium salt hydrate in which guanine anions form channels with water molecules filling in the channel space together with sodium cations coordinating them. The 1D anionic assembly generated through numerous hydrogen bonds and cation interactions with guanine anions and water molecules is energetically the most distinctive part of the structure of the potassium salt hydrate. In the case of the guanine sodium salt, the structure contains purely inorganic polymeric fragments – sodium cations coordinated to a water molecule forming a 1D polymeric structure and guanine anions interconnecting these polymers via hydrogen bonds with water molecules. The structural differences account for the difference in the anisotropy of strain on temperature variation for the two salt hydrates: whereas in both structures the values of the bulk thermal expansion coefficients are similar in the two structures and the major expansion is observed along the channel axes, the degree of anisotropy for the K salt is more than four times higher than that for the Na salt.

Crystal structure of the new palladium complexes tetrakis(1,3-dimethylimidazolium-2-ylidene)palladium(II) hexadecacarbonyltetrarhenium diethyl ether disolvate and octa-μ-carbonyl-dicarbonyltetrakis(triphenylphosphane)palladiumdirhenium (unknown solvate)

The investigation of the coordination chemistry of heterometallic transition-metal complexes of palladium (Pd) and rhenium (Re) led to the isolation and crystallographic characterization of tetrakis(1,3-dimethylimidazolium-2-ylidene)palladium(II) hexadecacarbonyltetrarhenium diethyl ether disolvate, [Pd(C5H8N2)4][Re4(CO)16]·2C4H10O or [Pd(IMe)4][Re4(CO)16]·2C4H10O, (1), and octa-μ-carbonyl-dicarbonyltetrakis(triphenylphosphane)palladiumdirhenium, [Pd4Re2(C18H15P)4(CO)10] or Pd4Re2(PPh3)4(μ-CO)8(CO)2, (2), from the reaction of Pd(PPh3)4 with 1,3-dimethylimidazolium-2-carboxylate and Re2(CO)10 in a toluene–acetonitrile mixture. In complex 1 the Re—Re bond lengths [2.9767 (3)–3.0133 (2) Å] are close to double the covalent Re radii (1.51 Å). The palladium–rhenium carbonyl cluster 2 has not been structurally characterized previously; the Pd—Re bond lengths [2.7582 (2)–2.7796 (2) Å] are about 0.1 Å shorter than the sum of the covalent Pd and Re radii (1.39 + 1.51 = 2.90 Å). One carbene ligand and a diethyl ether molecule are disordered over two positions with occupancy ratios of 0.5:0.5 and 0.625 (15):0.375 (15) in 1. An unidentified solvent is present in compound 2. The given chemical formula and other crystal data do not take into account the unknown solvent molecule(s). The SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] in PLATON was used to remove the contribution of the electron density in the solvent region from the intensity data and the solvent-free model was employed for the final refinement. The cavity with a volume of ca 311 Å3 contains approximately 98 electrons.