Structure of the high-temperature phase of caesium nitrate - the importance of high-resolution data.

A single-crystal structure determination of the cubic phase of CsNO based on data collected at 439 K up to sinθ/λ = 0.995000 Å, i.e.

Low-temperature phases of dicalcium barium hexakis(propanoate).

The structure determinations of phases (II) and (III) of barium dicalcium hexakis(propanoate) {or poly[hexa-μ-propanoato-bariumdicalcium], [BaCa(CHO)]} 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].

Crystal structures of -poly[[μ-aqua-di-aqua(μ-2-methyl-propano-ato-κ :,':')calcium] 2-methyl-propano-ate dihydrate], -poly[[μ-aqua-di-aqua-(μ-2-methyl-propano-ato-κ :,':')strontium] 2-methyl-propano-ate dihydrate] and -poly[[μ-aqua-di-aqua-(μ-2-methyl-propano-ato-κ :,':')(calcium/strontium)] 2-methyl-propano-ate dihydrate].

The crystal structures of -poly[[μ-aqua-di-aqua-(μ-2-methyl-propano-ato-κ :,':')calcium] 2-methyl-propano-ate dihydrate], {[Ca(CHO)(HO)](CHO)·2HO} , (I), -poly[[μ-aqua-di-aqua-(μ-2-methyl-propano-ato-κ :,':')strontium] 2-methyl-propano-ate dihydrate], {[Sr(CHO)(HO)](CHO)·2HO} , (II), and -poly[[μ-aqua-di-aqua-(μ-2-methyl-propano-ato-κ :,':')(calcium/strontium)] 2-methyl-propano-ate dihydrate], {[(Ca,Sr)(CHO)(HO)](CHO)·2HO} , (III), are related. (III) can be considered as an Sr-containing solid solution of (I), with Ca and Sr occupationally disordered in the ratio 0.7936 (16):0.

Crystal structure of poly[μ-aqua-bis(μ-2-methylpropanoato-κ :,':')dipotassium].

The structure of the title compound, [K(CHO)(HO)] , is composed of stacked sandwiches, which are formed by cation-oxygen bilayers surrounded by methyl-ethyl hydro-phobic chains. These sandwiches are held together by van der Waals inter-actions between the methyl-ethyl groups. The methyl-ethyl groups are disordered over two positions with occupancies 0.

Rerefinement of poly[di-aqua-bis-(μ-2-methyl-pro-pano-ato-κ :,':')bis-(μ-2-methyl-propano-ato-κ ::)(μ-2-methyl-propano-ato-κ :,')(2-methyl-propano-ato-κ ,')trilead(II)].

The crystal structure of the title complex, [Pb(CHO)(HO)] , was redetermined on basis of modern CCD-based single-crystal X-ray data at 120 K. The current study basically confirms the previous report [Fallon (1997 ▸). , , 19-23] at 190 K, but with higher accuracy and precision.

Layered alkali propano-ates (CHCOO); = Na, K, Rb, Cs.

The title alkali propano-ates poly[(μ-propano-ato)alkali(I)], (CHCOO), with alkali/ = Na, K, Rb and Cs, show close structural similarity, which is manifested by the coordination of the cations by six oxygen atoms in a chessboard motif, forming a bilayer. This bilayer is situated between hydro-phobic layers composed of dangling ethyl chains from the carboxyl-ate groups. Stacking of these two-dimensional sandwiches, which are parallel to (001), forms the title structures.

Caesium propano-ate monohydrate.

Caesium propano-ate monohydrate, Cs·CHO ·HO, is composed of two symmetry-independent Cs cations, which are situated on the special position 4 of space group 2 , one symmetry-independent propano-ate mol-ecule in a general position and a pair of water mol-ecules also situated on special position 4. Two pairs of these symmetry-independent cations, four propano-ate mol-ecules and two pairs of symmetry-independent water mol-ecules form a repeat unit. These units form columns that are directed along the axis and possess symmetry 2.

Poly[[tetra-deca-kis-(μ-propionato)hepta-barium] propionic acid monosolvate tetra-hydrate].

The title compound, {[Ba(CHO)]·0.946CHO·4HO} , is represented by a metal-organic framework structure that is held together by Ba-O-Ba bonds, as well as by O-H⋯O hydrogen bonds of moderate strength. The structure comprises of four independent Ba cations (one of which is situated on a twofold rotation axis), seven independent propionate and two independent water mol-ecules.

Degenerate (identity) chemical reactions in ferroelastic crystals.

The presence of degenerate chemical reactions in crystals is discussed. They take place in some order-disorder phase transitions in crystals. The other category of identity (degenerate) chemical reactions in crystals includes a few examples of domain reorientations with simultaneous hopping of atoms/ions in some ferroelastic crystals.

Pyridine-3-carboxamide-telluric acid (1/1).

In the title structure, CHNO·HOTe, the pyridine-3-carboxamide and telluric acid mol-ecules are inter-connected by conventional O-H⋯N, N-H⋯O and O-H⋯O hydrogen bonds of moderate strength as well as by π-π inter-actions between the pyridine rings. The strongest hydrogen bond in the structure is formed between a hydroxyl group of the HTeO mol-ecule and the -pyrimidine N atom. The structure is unusual because of presence of the alternating sheets, which contain HTeO and pyridine-3-carboxamide mol-ecules, respectively.

A resonance-assisted intra-molecular hydrogen bond in compounds containing 2-hy-droxy-3,5-di-nitro-benzoic acid and its various deprotonated forms: redetermination of several related structures.

A large number of structural determinations of compounds containing 2-hy-droxy-3,5-di-nitro-benzoic acid () and its various deprotonated forms, 2-hy-droxy-3,5-di-nitro-benzoate () or 2-carb-oxy-4,6-di-nitro-phenolate (), are biased. The reason for the bias follows from incorrectly applied constraints or restraints on the , which is involved in the intra-molecular hydrogen bond between the neighbouring carb-oxy-lic/carboxyl-ate and oxo/hy-droxy groups. This hydrogen bond belongs to the category of resonance-assisted hydrogen bonds.

Bis(3-carbamoylpyridin-1-ium) phosphite mono-hydrate.

Two of the constituent mol-ecules in the title structure, 2CHNO·HPO·HO, the phosphite anion and the water mol-ecule, are situated on a symmetry plane. The mol-ecules are held together by moderate N-H⋯O and O-H⋯N, and weak O-H⋯O and C-H⋯O hydrogen bonds in which the amide and secondary amine groups, and the water molecules are involved. The structural features are usual, among them the H atom bonded to the P atom avoids hydrogen bonding.

4-Amino-benzoic acid 4-methyl-pyridine/4-methyl-pyridinium 4-amino-benzoate 0.58/0.42: a redetermination from the original data.

The title structure, 4-amino-benzoic acid 4-methyl-pyridine/4-methyl-pyridinium 4-amino-benzoate 0.58/0.42, 0.

A long symmetric N⋯H⋯N hydrogen bond in bis-(4-amino-pyridinium)(1+) azide(1-): redetermination from the original data.

The structure of the title mol-ecular salt, CHN·N, has been redetermined from the data published by Qian & Huang [ (2010), E, o3086; refcode WACMIY (Groom , 2016)]. The improvement of the present redetermination consists in a correction of the site-occupancy parameter of the bridging H atom between the pyridine rings, as well as of its position. The present study has shown that the bridging H atom (site symmetry 2) is involved in a symmetric N⋯H⋯N hydrogen bond, which is one of the longest ever observed [N⋯N = 2.

Crystal structure of 2--butyl-2,3-di-hydro-1-benzo[]pyrrol-1-one.

The asymmetric unit of the title compound, CHNO, comprises two sym-metry-independent mol-ecules which differ mainly in the conformations of the -butyl groups. The mol-ecules contain an essentially planar five-membered 3-pyrroline ring incorporating a carbonyl substituent (pyrrolinone) which forms part of an isoindolinone skeleton. The planarity of the pyrrole ring is compared to other structures with isoindolinone.

A study of the planarity of the pyrrolone fragment in 2-isopropyl-2,3-dihydro-1H-isoindol-1-one.

Orthophthalaldehyde (o-phthalaldehyde, OPA) is an aromatic dialdehyde bearing two electron-withdrawing carbonyl groups. The reactions of OPA with primary amines are broadly applied for the synthesis of important heterocyclic compounds with biological relevance. A number of such reactions have been investigated recently and several structures of condensation products have been reported, however, the complex reaction mechanism is still not fully understood and comprises concurrent as well as consecutive reactions.

A redetermination from the original data of the crystal structure of 2-amino-4,6-di-meth-oxy-pyrimidin-1-ium 4-amino-benzoate.

The title structure, C6H9.5N3O2 (0.5+)·C7H6.

Redetermination of cytosinium hydrogen maleate-cytosine (1/1) from the original data.

The title salt, C4H6N3O(+)·C4H3O4 (-)·C4H5N3O, has been redetermined from the data published by Benali-Cherif, Falek & Direm [Acta Cryst. (2009), E65, o3058-o3059]. The improvement of the present redetermination consists in the discovery of the splitting of one of the H atoms into two disordered positions, the occupancies of which are equal to 0.

Structure determination of KScS₂, RbScS₂ and KLnS₂ (Ln = Nd, Sm, Tb, Dy, Ho, Er, Tm and Yb) and crystal-chemical discussion.

The title structures of KScS2 (potassium scandium sulfide), RbScS2 (rubidium scandium sulfide) and KLnS2 [Ln = Nd (potassium neodymium sufide), Sm (potassium samarium sulfide), Tb (potassium terbium sulfide), Dy (potassium dysprosium sulfide), Ho (potassium holmium sulfide), Er (potassium erbium sulfide), Tm (potassium thulium sulfide) and Yb (potassium ytterbium sulfide)] are either newly determined (KScS2, RbScS2 and KTbS2) or redetermined. All of them belong to the α-NaFeO2 structure type in agreement with the ratio of the ionic radii r(3+)/r(+). KScS2, the member of this structural family with the smallest trivalent cation, is an extreme representative of these structures with rare earth trivalent cations.

High- and low-temperature phases in isostructural 4-chloro-3-nitroaniline and 4-iodo-3-nitroaniline.

The structures of 4-chloro-3-nitroaniline, C6H5ClN2O2, (I), and 4-iodo-3-nitroaniline, C6H5IN2O2, (II), are isomorphs and both undergo continuous (second order) phase transitions at 237 and 200 K, respectively. The structures, as well as their phase transitions, have been studied by single-crystal X-ray diffraction, Raman spectroscopy and difference scanning calorimetry experiments. Both high-temperature phases (293 K) show disorder of the nitro substituents, which are inclined towards the benzene-ring planes at two different orientations.

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).

The X-ray single-crystal structure determinations of the chemically related compounds 2-amino-1,3,4-thiadiazolium hydrogen oxalate, C2H4N3S(+)·C2HO4(-), (I), 2-amino-1,3,4-thiadiazole-succinic acid (1/2), C2H3N3S·2C4H6O4, (II), 2-amino-1,3,4-thiadiazole-glutaric acid (1/1), C2H3N3S·C5H8O4, (III), and 2-amino-1,3,4-thiadiazole-adipic acid (1/1), C2H3N3S·C6H10O4, (IV), are reported and their hydrogen-bonding patterns are compared. The hydrogen bonds are of the types N-H···O or O-H···N and are of moderate strength. In some cases, weak C-H···O interactions are also present.

Redetermination of NaGdS2, NaLuS2 and NaYS2.

The title structures NaGdS2 (sodium gadolinium sulfide), NaLuS2 (sodium lutetium sulfide) and NaYS2 (sodium yttrium sulfide) were redetermined in order to improve the structural information available for the family of group 1 and thallium rare earth sulfides, which are isostructural with the rhombohedral α-NaFeO2 structure type. In particular, the present investigation has been directed at the rhombohedral sodium rare earth sulfides. The observed dependence of the fractional coordinate z(S(2-)) on the identity of the rare earth element in the newly determined structures is in agreement with the known structures of the potassium and rubidium analogues.

Structure determination of KLaS2, KPrS2, KEuS2, KGdS2, KLuS2, KYS2, RbYS2, NaLaS2 and crystal-chemical analysis of the group 1 and thallium(I) rare-earth sulfide series.

One of the purposes of this work is to provide a crystallographic review of group 1 and thallium rare-earth ternary sulfides M(+)Ln(3+)S2. We have therefore determined crystal structures of KLaS2, KPrS2, KEuS2, KGdS2, KLuS2, KYS2, RbYS2, which belong to the α-NaFeO2 structural family (R3m), as well as NaLaS2, which is derived from the disordered NaCl structural type (Fm3m). The determined structures were compared with known members of the group 1 as well as thallium(I) rare-earth sulfides by the standard tools of crystal-chemical analysis such as comparison of bond-valences, analysis of interatomic distances and comparison of the unit-cell parameters.

N-[Amino(imino)methyl]uronium tetrafluoroborate.

In the title compound, C(2)H(7)N(4)O(+)·BF(4) (-), inter-molecular N-H⋯O hydrogen bonds connect the cations into chains parallel to the c axis, with graph-set motif C(4). These chains are in turn connected into a three-dimensional network by inter-molecular N-H⋯F hydrogen bonds. The B-F distances distances in the anion are not equal.

Mixed crystals of 2-carbamoylguanidinium with hydrogen fluorophosphonate and hydrogen phosphite in the ratios 1:0, 0.76 (2):0.24 (2) and 0.115 (7):0.885 (7).

The title compounds, 2-carbamoylguanidinium hydrogen fluorophosphonate, C(2)H(7)N(4)O(+)·HFO(3)P(-), (I), 2-carbamoylguanidinium-hydrogen fluorophosphonate-hydrogen phosphite (1/0.76/0.24), C(2)H(7)N(4)O(+)·0.