Are crystal structures getting better? A temporal and elemental analysis of the Cambridge Structural Database

A statistical evaluation of the entries in the Cambridge Structural Database reveals trends in structural quality as described by the accessible quality indicators in the CSD with respect to the structures' publication year and the elements contained.

Eu₅Ga₂As₆ and Ba₅In₂As_6–xSb_x: new As-containing members of the Sr₅Al₂Sb₆ structure type

The first As-containing representatives of the Sr₅Al₂Sb₆ structure type are reported. The anionic sub­structures in Eu₅Ga₂As₆ and Ba₅In₂As_6–xSb_x [x = 0.49 (2) and 2.92 (2)] com­prise 1D chains of corner- and edge-sharing [TrPn₄] tetra­hedra with pendant [Pn₂] dumbbells (Tr = Ga, In; Pn = As, Sb). The mixed-pnictogen phases reveal site-selective As/Sb substitution as a potential route for tuning the bonding and physical properties of this family.

Solvent-free thallium(I) tetra­kis­[3,5-bis­(tri­fluoro­meth­yl)phen­yl]borate: crystal structure, supra­molecular inter­actions and anisotropic thermal expansion

The solvent-free structure of the thallium(I) salt of the weakly coordinating anion tetra­kis­[3,5-bis­(tri­fluoro­meth­yl)phen­yl]borate, Tl[BC₃₂H₁₂F₂₄], exhibits short Tl⋯F contacts and a supra­molecular architecture governed by C—H⋯F hy­dro­gen bonds and weak F⋯F and C—F⋯π inter­actions. Disorder and tilting of the arene rings generate different close-contact motifs, giving rise to hinge-like inter­molecular inter­actions and pronounced anisotropic thermal expansion along the crystallographic a and b axes.

Crystal structure of fucoxanthin: resolving a long-standing crystallographic challenge

The first small-mol­ecule single-crystal X-ray structure of fuco­xanthin is reported, resolving a long-standing crystallographic problem in carotenoid structural chemistry.

Conformation and supra­molecular assembly in an azo–azomethine–pyrazole hybrid: crystal structure, Hirshfeld surface and QTAIM analyses

An azo–azomethine–pyrazole donor–π–acceptor hybrid crystallizes with two independent mol­ecules (Z′ = 2) linked through a co-operative network of O—H⋯N, C—H⋯O and C—H⋯N inter­actions. Hirshfeld surface and QTAIM analyses reveal the hierarchical contribution of strong and weak noncovalent inter­actions to the conformational stabilization and supra­molecular assembly of the crystal structure.

Uranyl derivatives: discovering features by com­paring related crystal structures

A brief overview of the existing data on related UO₂²⁺-containing crystal structures uncovered some peculiarities about three new derivatives. The first crystal structure with simultaneously present H₃O⁺ and Be²⁺ cations was solved. The rigidity of topology to the change of the nature of the fragments and ways to control the atom environment via the ratio of the reagents are discussed.

Synthesis and crystal structure characterization of Na[Fe₄S₃(NO)₇]·5H₂O

The title com­pound is a hydrated sodium salt of a nitrosyl iron–sulfur cluster. While retaining the typical [Fe₄S₃(NO)₇]⁻ core framework, a unique one-dimensional hy­dro­gen-bonded supra­molecular network is formed induced by Na⁺. The refinement process properly handled the 60° rotational disorder phenomenon of the anion in this structure.