Expanding the scope and influence of Acta Crystallographica Section B

Editorial

Why don't we find more polymorphs?

Crystal structure prediction methods usually generate more thermodynamically feasible structures than known polymorphs. Some reasons for this are discussed in the light of studies where computed crystal energy landscapes have been contrasted with experimental searches for solid forms.

Modulated structure of Lu₄AlCu₂B₉O₂₃ from low-temperature single-crystal X-ray data

The origins and features of incommensurate structural modulation are discovered in a single crystal of Lu₄AlCu₂B₉O₂₃ on cooling down to 110 K.

Proton ordering in (NH₄)₃H(SO₄)₂ at low-temperature phase transitions

The proton ordering plays an important role in the structural phase transitions of (NH₄)₃H(SO₄)₂ at low temperature. Crystal structure analysis using neutron diffraction reveals a sequential ordering of the ammonium groups and of the proton in the (SO₄)H(SO₄) dimer with decreasing temperature, related to the different phase transitions.

Electron density distribution in tetralithium hypodiphosphate hexahydrate, Li₄P₂O₆·6H₂O

Charge density distribution in tetralithium hypodiphosphate hexahydrate Li₄P₂O₆·6H₂O has been studied experimentally and by theoretical calculations; the reasons for the rigidity of the electron density distribution in the hypodiphosphate anion are discussed.

An alternative approach to rationalizing the structures of the cyclotrisilicates: Rb₁₀[Si₆O₁₇], Cs₈[Si₆O₁₆] and Na₃Y[Si₆O₁₅] by viewing them in light of the extended Zintl–Klemm concept

The extended Zintl–Klemm concept accounts for the structures of the three dimeric cyclotrisilicate anions [Si₆O₁₇]¹⁰⁻, [Si₆O₁₆]⁸⁻ and [Si₆O₁₅]⁶⁻ as Zintl polyanions of composition [Ψ-S₄P₂]¹⁰⁻, [Ψ-S₂P₄]^8– and [Ψ-P₆]⁶⁻, respectively.

Structure and properties of domperidone and its succinate salt

Crystal structure of domperidone {or 5-chloro-1-(1-[3-(2-oxo-2,3-dihydro-1H-benzo[d]imidazol-1-yl)propyl]piperidin-4-yl)-1H-benzo[d]imidazol-2(3H)-one} and domperidone succinate salt. The domperidone succinate salt shows higher solubility and dissolution rate with respect to the pure drug.

The importance of screening solid-state phases of a racemic modification of a chiral drug: thermodynamic and structural characterization of solid-state phases of etiracetam

In this contribution different solid-state forms of the racemic compound (RS)-2-(2-oxo-pyrrolidin-1yl)-butyramide are studied from a structural and thermal point of view and compared to the enantiopure compound.

Role of chloroform and di­chloro­methane solvent molecules in crystal packing: an interaction propensity study

Analysis of 770 structures containing chloroform and 919 structures containing dichloromethane shows that around 80% of both molecules use their acidic C—H protons in hydrogen-bond formation in crystal structures, but their Cl atoms would appear to make only a limited contribution to crystal aggregation.

Influence of supramolecular structures in crystals on parallel stacking interactions between pyridine molecules

Parallel stacking interactions between pyridine molecules in crystal structures and the influence of supramolecular structures in crystals on the geometry of interactions were studied by analyzing data in the Cambridge Structural Database (CSD).

Deca­fluoro­cyclohex-1-ene at 4.2 K – crystal structure and theoretical analysis of weak interactions

The crystal structure of the title compound was solved from neutron powder diffraction data and refined by energy minimization in the solid state. Weak intermolecular interactions were analysed by theoretical molecular calculations.

Methylthioureas and their morpholine and dioxane adducts; hydrogen-bonding patterns

The structures of three methyl-substituted thioureas and three related adducts with morpholine or 1,4-dioxane are presented and their hydrogen-bonding patterns discussed.

Zn- and Co-based layered double hydroxides: prediction of the a parameter from the fraction of trivalent cations and vice versa

A recently proposed method to calculate the a parameter of the unit cell of layered double hydroxides from the fraction of trivalent cations is extended to Zn- and Co-based phases. It is shown to be useful as a sanity test for extant and future structure determinations and computer-simulation studies.

Problems in Structural Inorganic Chemistry