The cover image highlights the great contributions of Prof. Gordon J. Miller to the understanding of chemical bonding in complex extended solids in relation to their crystal structure and properties. More details to the special collection “Dedicated to Professor Gordon Miller on the Occasion of His 65th Birthday” can be found in the Laudatio 2500095 by Kirill Kovnir, Weiwei Xie, Fei Wang, Jakoah Brgoch, and Yurij Mozharivskyj.

The two electron-precise compounds comprise beside sodium cations two types of anions: tetrahedral [SnPn₄]⁸⁻ beside [Pn₃Sn-SnPn₃]¹²⁻ dimers. In the case of Pn = P, an interesting disorder reveals that in addition trigonal planar [SnP₃]⁵⁻ units occur. The latter arises from a shift of the central Sn atom in the center of the triangular face of the SnP₄ tetrahedron.

The crystal structure of Ca₄CdIn₂Ge₄, a quaternary variant of the monoclinic Mg₅Si₆ structure, consists of [InGe₄] tetrahedra, interconnected by Ge₂ dimers and [CdGe₄] square-planar units

Unlike the other group-I γ-brass type phases, γ-Ag_5+δZn_8-δ shows substitutional disorder in every crystallographic site though the coloring scheme is allied to γ-Cu₅Zn₈. DFT-based theoretical calculation shows that the phase is stabilized by Fermi Surface-Brilloiun Zone interaction. The substitutional disorder is guided by relatively weak heteroatomic interaction and elongated homoatomic interactions of the majority element.

Yb₁₄CdSb₁₁ has been synthesized in both single crystals and polycrystalline powder form. We perform heat capacity measurements on single crystals and thermoelectric transport properties from room temperature to 1000˚C. We show that as prepared in high yield, this compound is a promising thermoelectric material. We propose how to optimize the composition further to improve the properties.

A revised crystal structure of La(OH)₂Cl is reported in space group P2₁/m and is isostructural to a series of Ln(OH)₂Cl (Ln = Ce – Lu excluding Pm). The data collected herein are compared to the previously published La(OH)₂Cl in the space group P2/m. An updated hydrothermal synthesis and revised crystallographic structure for La(OH)₂Cl in P2₁/m are reported.

Unprecedented chains of Mn3-triangles enable ferrimagnetic behavior in TiM_1–xOs_2+xB₂ with Curie temperature of ≈125 K, a negative Weiss constant of −173 K, and a large coercivity of coercivity of 36 kA m−₁.

The cubic room-temperature structure of (Bi₉)[Cu₈I₁₃] shows dynamic effects that involve fluctuations in bonding within the (Bi₉)⁵⁺ polycation and mobility of the Cu⁺ cations. Flash freezing results in a fully ordered, polar monoclinic structure, which can be interpreted as a hierarchical filling variant of the NaZn₁₃ structure type. (Bi₉)[Cu₈I₁₃] is an electronic semiconductor and a copper ionic conductor.

The synthesis, structures, and properties of two triel-containing quaternary arsenides are investigated.

By filling a part of the pentagonal tunnels in a tetragonal bronze type unit, ordered structures are formed for well-defined compositions whereas others lead to defective intergrowth structures that can be characterized by high-resolution electron microscopy methods.

A noncentrosymmetric metal-chalcogenide structure has been stabilized by two different types of site disorder, as represented by M = Ag versus M = Cu in the graphic.

Pr₂Si₇ is obtained by high-pressure, high-temperature synthesis. The topological coordination numbers underline the significance of the silicon partial structure. The homoatomic connectivity within the polyanionic framework in combination with the formation of lone pairs clearly indicates a hypervalent bonding situation for silicon. The degenerate electronic f ² state of the Pr³⁺ ion is split by the crystalline electric field.

Hf4Nb2Al7 and Hf6Al7 were synthesized from the elements and crystallize in the rhombohedral W6Fe7 type structure. Single crystals showed obverse-reverse twinning. In addition, 27Al NMR investigations, magnetic measurements and quantum-chemical calculations were conducted.

The structure of La3MC2 is comprised of layers of C24- anions in octahedral coordination by La3+ cations, sandwiched between layers of M anions surrounded by 8 La3+ cations (shown as polyhedra).