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Controlling the elastic properties of the material could become a powerful tool for tuning the thermal transport in solids. Nevertheless, the impact of the crystal structure, chemical bonding, and elastic properties on the lattice thermal conductivity remains to be elucidated. This is a pivotal issue for the advancement of thermoelectric (TE) materials. In this context, the influence of cation substitution in tetrahedral voids on the structural, thermal, and TE properties of α- and β-Pb y Ga 6- x In x Te 10 ─filled β-Mn-type phases─is reported here. The investigated materials show semiconducting behavior and a change from p- to n-type conductivity, depending on the chemical composition and temperature. Our findings indicate that the electronic transport in β-Mn-type phases is largely influenced by the substantial distortion of the Te framework, which causes the low weighted mobility and strong scattering of charge carriers. The presence of a significant anharmonicity of lattice vibrations results in the ultralow lattice thermal conductivity of Pb y Ga 6- x In x Te 10 materials. With increasing x , κ L decreases from 0.59 to an extremely low value of 0.36 W m -1 K -1 at 298 K due to the decrease of bonding energy, intensification of anharmonic thermal vibrations of atoms, and formation of point defects. This work demonstrates the efficacy of utilizing the crystal structure and elastic properties to regulate phonon transport in functional materials.

Single-phase NaGa4 samples were prepared by annealing stoichiometric element mixtures at 200 °C, 300 °C, and 450 °C in closed tantalum ampoules. No compositional homogeneity range was detected. While single crystals annealed at 200 °C feature a fully ordered crystal structure, a crystal annealed at 300 °C reveals a defect with mutual exchange of Na atoms and Ga2 dumbbells. The structure motif caused by the violation of translational symmetry resembles the CeMg2Si2 type of structure. The NaGa4 structure constitutes a branch of the BaAl4 type distinguished by a notably high c/a ratio (space group I4/mmm; a = 4.2261(1) Å, c = 11.2633(6) Å, c/a = 2.67). This distortion enables the adaption of the BaAl4-type to small cations, when the further shortening of the apical-apical distance d(Ga-Ga) is not possible any more. Therefore, NaGa4 offers an adaption alternative to the monoclinic distortion observed in the CaGa4 and YbGa4. Conductivity measurements validate the metallic behavior anticipated by NMR measurements in earlier studies., (© 2024 Wiley‐VCH GmbH.)

In the large class of main-group Zintl phases, the octet rule plays a key role for the polyanions following the pseudoatom concept and the 8- N rule, such that a unique correspondence between atomic partial structure and its electron count results. In the conceptual framework of the Wade's type of clusters the relations to the octet rule are less obvious, and its structural implications are not clear. For this purpose, a topological implementation of the octet rule (TORI) within a delocalized bonding scenario is introduced. It is based on the average topology of the deltahedral cluster skeletons and the octet rule applied to delocalized fractional 2- and 3-center bond distributions. For a given skeletal electron pair count SEP, TORI yields values ( t toc , y toc ) similar to the styx approach. Two hierarchically different types of octet-rule fulfillment are identified, the cluster-wise and the local one. The local octet-rule fulfillment always implies the cluster-wise one, while the converse is not true. Deltahedral clusters with different skeletal shapes but the same Wade's SEP count can be distinguished with respect to different octet-rule fulfillment. The TORI approach opens a perspective to compare Zintl phases containing Wade-type clusters with those containing 8- N type of partial structures on the basis of octet-rule implications. The main difference to the 8- N type of partial structures identified is the more flexible way of octet-rule fulfillment in the Wade's type clusters, which does not prevent them from realizing the same cluster topology with different SEP counts. The TORI approach works with delocalized fractional bonds and is consistent with the concept of PSEPT; it just adds an additional facet.

In the course of systematic studies of intermetallic compounds Ga 3 TM (TM─transition metal), the compound Ga 3 Rh is synthesized by direct reaction of the elements at 700 °C. The material obtained is characterized as a high-temperature modification of Ga 3 Rh. Powder and single-crystal X-ray diffraction analyses reveal tetragonal symmetry (space group P 4 2 / mnm , No. 146) with a = 6.4808(2) Å and c = 6.5267(2) Å. Large values and strong anisotropy of the atomic displacement parameters of Ga atoms indicate essential disorder in the crystal structure. A split-position technique is applied to describe the real crystal structure of ht -Ga 3 Rh. Bonding analysis in ht -Ga 3 Rh performed on ordered models with the space groups P 1̅, P 4 2 nm , and P 4 2 2 1 2 shows, besides the omnipresent heteroatomic Ga-Rh bonds in the rhombic prisms ∞ 3 [Ga 8/2 Rh 2 ], the formation of homoatomic Ga-Ga bonds bridging the Rh-Rh contacts and the absence of significant Rh-Rh bonding. These features are essential reasons for the experimentally observed disorder in the lattice. In agreement with the calculated electronic density of states, ht -Ga 3 Rh shows temperature-dependent electrical resistivity of a "bad metal". The very low lattice thermal conductivity of less than 0.5 W m -1 K -1 at 300 K, being lower than those for most other Ga 3 TM compounds, correlates with the enhanced bonding complexity.

The Zintl phase CaSi 2 is a layered compound with stacking variants known as 1P, 3R, and 6R. We extend the series by the 21R polytype formed by rapid cooling of the melt. The crystal structure of 21R-CaSi 2 (space group R 3̅ m ) was derived from HRTEM images, and the atomic positions were optimized by using the FPLO code ( a = 3.868 Å, c = 107.276 Å). We explore polytype transformations by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron backscattering diffraction (EBSD), and thermal analysis. While 6R-CaSi 2 is thermodynamically stable at ambient conditions, nanosized impurities of silicon stabilize 3R-CaSi 2 as a bulk phase.

LiCa 8 [Cr IV N 3 ] 2 N 2 F ( Pnnm (#58), a = 17.5230(13) Å, b = 7.3379(5) Å, c = 4.9433(4) Å) is an example of a multinary nitridochromate fluoride, that provides additional information on almost elusive tetravalent nitridochromates. Shorter Cr-N bond lengths compared to those in the previously reported nitridochromates(III), as well as diamagnetic behavior and vibrational spectroscopy data suggest Cr(IV), which is in good agreement with the charge balance and crystal structure refinement. According to band structure calculations, LiCa 8 [Cr IV N 3 ] 2 N 2 F is a semiconductor with a band gap of 1.1 eV. The compound features trigonal planar [CrN 3 ] 5 - units of C s symmetry, and lithium, calcium, nitrogen and fluorine atoms arranged in a fragment of the rock salt type structure.

This work presents a study on a new uranium iron arsenide UFe 5 As 3 . By implementing Bi-flux synthesis, we were able to grow mm-sized single crystals of this compound, which show twinning. UFe 5 As 3 is one of only two known uranium iron arsenides. It adopts a monoclinic, UCr 5 P 3 -type crystal structure (space group P 2 1 / m , Pearson symbol mP 18, a = 7.050(2) Å, b = 3.8582(9) Å, c = 9.634(1) Å, β = 100.25(1)°). The magnetic susceptibility of UFe 5 As 3 indicates it to be an antiferromagnet with T N = 47 K and μ eff = 4.94 μ B per formula unit, signaling that both U and Fe are likely magnetic in this material. The material appears to be anisotropic, with a small (likely ferromagnetic) spin reorientation transition around T = 29 K. The Sommerfeld coefficient γ 0 = 135 mJ mol -1 K -2 suggests enhanced effective electron mass in UFe 5 As 3 , while electrical resistivity indicates metallic, Kondo-like behavior.

Samples of the pseudo-binary system Na 2- x Li x Ga 7 ( x ≤ 1) were synthesized from the elements at 300 °C in sealed Ta ampoules or by the reaction of Na 2 Ga 7 with LiCl. The peritectic formation temperature decreases with increasing Li content from 501(2) °C ( x = 0) to 489(2) °C ( x = 1). The boundary compositions Na 2 Ga 7 and Na 1 Li 1 Ga 7 crystallize with different structure types related by a group-subgroup relation. While the Na-rich compositions ( x ≤ 0.5) represent a substitutional solid solution (space group Pnma ), the Li-rich compositions feature an unconventional replacement mechanism in which Li atoms occupying interstitial positions induce vancancies at the Na positions (space group Cmce ). The crystal structure of Na 1 Li 1 Ga 7 ( a = 8.562(1) Å, b = 14.822(2) Å, c = 11.454(2) Å; Z = 8) was determined from X-ray single-crystal diffraction data, and reveals an anionic framework comprising 12-bonded Ga 12 icosahedra and 4-bonded Ga atoms, with alkali-metal atoms occupying channels and cavities. The arrangement of cations makes NaLiGa 7 a new structure type within the MgB 12 Si 2 structure family. Band structure calculations for the composition NaLiGa 7 predict semiconducting behavior consistent with the balance [Na + ] 2 [Li + ] 2 [(Ga 12 ) 2- ][Ga - ] 2 , considering closo Wade clusters [(12b)Ga 12 ] 2- and Zintl anions [(4b)Ga] - . Susceptibility measurements indicate temperature-independent diamagnetic behavior.

During the investigation of the binary system Be-Ru two new phases - Be 7 Ru 4 and Be 12 Ru 7 - with similar compositions (63.6 at. % Be and 63.2 at. % Be, respectively), are discovered. They both represent new structural prototypes. The phases are located between Be 2 Ru (Fe 2 P-type structure) and Be 3 Ru 2 (U 3 Si 2 -type structure) in the phase diagram. This explains why their crystal structures, solved and refined from single crystal X-ray diffraction data, are described as 2D intergrowth of Fe 2 P and U 3 Si 2 motives. The calculated electronic density of stats (DOS) reveals pronounced minima in the vicinity of the Fermi level for both compounds. Position-space analysis of chemical bonding exhibits the formation of three- and four-atomic polar bonds, involving both, Ru and Be, atoms, and a strong charge transfer from Be to the more electronegative Ru., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The quaternary nitridochromate(IV) LiSr 2 [CrN 3 ] crystallizes in a new structure type with the non-centrosymmetric space group P 2 1 (no. 4) with a = 5.5685(7) Å, b = 5.3828(8) Å, c = 7.5381(1) Å, and β = 92.291(8)°. Predominant structural features of the compound are slightly nonplanar trigonal units [CrN 3 ] 5- , which are connected by three-fold coordinated lithium to form slabs in the (001) plane. Shorter Cr-N bond lengths in comparison with reported nitridochromates(III), as well as diamagnetic behavior and vibrational spectroscopy data indicate Cr(IV), which is in a good agreement with the charge balance. According to electronic structure calculations, the compound is a semiconductor with a band gap of 1.19 eV.

Clathrate phases with crystal structures exhibiting complex disorder have been the subject of many prior studies. Here we report syntheses, crystal and electronic structure, and chemical bonding analysis of a Li-substituted Ge-based clathrate phase with the refined chemical formula Ba 8 Li 5.0(1) Ge 41.0 , which is a rare example of ternary clathrate-I where alkali metal atoms substitute framework Ge atoms. Two different synthesis methods to grow single crystals of the new clathrate phase are presented, in addition to the classical approach towards polycrystalline materials by combining pure elements in desired stoichiometric ratios. Structure elucidations for samples from different batches were carried out by single-crystal and powder X-ray diffraction methods. The ternary Ba 8 Li 5.0(1) Ge 41.0 phase crystallizes in the cubic type-I clathrate structure (space group Pm 3̄ n no. 223, a ≈ 10.80 Å), with the unit cell being substantially larger compared to the binary phase Ba 8 Ge 43 (Ba 8 □ 3 Ge 43 , a ≈ 10.63 Å). The expansion of the unit cell is the result of the Li atoms filling vacancies and substituting atoms in the Ge framework, with Li and Ge co-occupying one crystallographic (6 c ) site. As such, the Li atoms are situated in four-fold coordination environment surrounded by equidistant Ge atoms. Analysis of chemical bonding applying the electron density/electron localizability approach reveals ionic interaction of barium with the Li-Ge framework, while the lithium-germanium bonds are strongly polar covalent.

Application of chemical bonding analysis in position-space techniques based on combined topological analysis of the electron density and electron-localizability indicator distributions has recently led to the formulation of a polarity-extended 8 - N eff rule for consistent inclusion of quantum chemically obtained polar-covalent bonding data into the classical 8 - N scheme for main-group compounds. Previous application of this scheme to semiconducting main-group compounds of the cubic MgAgAs type of structure with 8 valence electrons per formula unit (8 ve per f.u.) has shown a covalent bonding tendency preferring one zinc blende type partial structure over the other one, which seems to corroborate the classical Lewis picture of maximally four covalent bonds per main-group element. In contrast to the MgAgAs type, the orthorhombic TiNiSi type of structure displays a much higher geometrical flexibility to incorporate different kinds of metal atoms. The analysis of polar-covalent bonding in semiconducting 8 ve per f.u. containing main-group compounds AA ' E of this structure type reveals a transition to non-Lewis type bonding scenarios of species E with up to ten polar-covalently bonded metal atoms. This kind of situation is consistently included into the extended 8 - N eff type bonding scheme. A systematic increase of partially covalent bonding from chalcogenides E 16 to the tetrelides E 14 is found, summing up to as much as 2 covalent bonds E 14 -A and E 14 - A ', and correspondingly remaining 4 lone pair type electrons on species E 14 . The familiar notion of this structure type consisting of a '[NiSi]'-type framework with 'Ti'-type atoms filling the voids cannot be supported for the compounds investigated.

The structural features of the hexagonal layered crystal structure of Be 2 Ru (a=5.7508(3) Å, c=3.0044(2) Å, space group P 6 ‾ ${\bar{6}}$ 2m) were investigated by single crystal X-ray diffraction and transmission electron microscopy (TEM). The residual electron density and high-resolution TEM images show that the real structure can be described as an intergrowth of the main hexagonal matrix of the Fe 2 P type with minor orthorhombic inclusions of its stacking variants. Such atomic arrangement is stabilized by the charge transfer from Be to Ru and by a system of polar three- and four-atomic bonds involving both components. The calculated electronic density of states (DOS) of Be 2 Ru revealed, contrarily to typical intermetallic compounds, a pseudo gap (dip) in the vicinity of the Fermi level. The temperature dependence of the electrical resistivity of Be 2 Ru shows metal behaviour in agreement with the non-zero DOS at the Fermi level., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Na 2 Ga 7 crystallizes with the orthorhombic space group Pnma (no. 62; a = 14.8580(6) Å, b = 8.6766(6) Å, and c = 11.6105(5) Å; Z = 8) and constitutes a filled variant of the Li 2 B 12 Si 2 structure type. The crystal structure consists of a network of icosahedral Ga 12 units with 12 exohedral bonds and four-bonded Ga atoms in which the Na atoms occupy the channels and cavities. The atomic arrangement is consistent with the Zintl [(4b)Ga] - and Wade [(12b)Ga 12 ] 2- electron counting approach. The compound forms peritectically from Na 7 Ga 13 and the melt at 501 °C and does not show a homogeneity range. The band structure calculations predict semiconducting behavior consistent with the electron balance [Na + ] 4 [(Ga 12 ) 2- ][Ga - ] 2 . Magnetic susceptibility measurements show that Na 2 Ga 7 is diamagnetic.

In a pilot study, electron-density (ED) and ED Laplacian distributions were reconstructed for the challenging case of CaB 6 (Pearson symbol cP7) with conceptually fractional B-B bonds from quantum-chemically calculated structure-factor sets with resolutions 0.5 Å -1 ≤ [sin(θ)/λ] max ≤ 5.0 Å -1 by means of Fourier-synthesis techniques. Convergence of norm deviations of the distributions obtained with respect to the reference ones was obtained in the valence region of the unit cell. The QTAIM (quantum theory of atoms in molecules) atomic charges, and the ED and ED Laplacian values at the characteristic critical points of the Fourier-synthesized distributions have been analysed for each resolution and found to display a convergent behaviour with increasing resolution. The presented method(exponent) (ME) type of Fourier-synthesis approach can qualitatively reconstruct all characteristic chemical bonding features of the ED from valence-electron structure-factor sets with resolutions of about 1.2 Å -1 and beyond, and from all-electron structure-factor sets with resolutions of about 2.0 Å -1 and beyond. Application of the ME type of Fourier-synthesis approach for reconstruction of ED and ED Laplacian distributions at experimental resolution is proposed to complement the usual extrapolation to infinite resolution in Hansen-Coppens multipole model derived static ED distributions., (open access.)

The compound Ge 32 Co 9-x (x=0.54(6), a=10.9861(3) Å, space group Im 3 ‾ $\bar 3$ m) prepared under high pressure and at high temperature is metastable under ambient conditions. It crystallizes in a new structure type, Pearson symbol cI82-1.08. The crystal structure represents a slightly distorted cubic primitive arrangement of germanium atoms with part of the Ge cubes filled by cobalt. Analysis of the chemical bonding by real-space methods revealed three-core cluster units Ge 16 Co 3 and seemingly empty regions comprising either covalent inter-polyhedral Ge-Ge bonds or lone-pairs located at the germanium atoms. The electrical conductivity is metal-like., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Quaternary (Sn,Pb,Bi)Pt was synthesized by melting of the elements in an evacuated silica glass ampoule. The crystal structure was established by single-crystal X-ray diffraction and adopts an atomic arrangement of the NiAs type with additional occupation of the voids. Decisive for the refinement was the composition of the crystals as determined by energy dispersive X-ray spectroscopy (EDXS), resulting in a formula of (Sn 0.15 Pb 0.54 Bi 0.31 )Pt., (© Rössner et al. 2023.)

Amalgams have played an important role in fundamental and applied solid-state chemistry and physics because of the diversity of crystallographic features and properties that they have to offer. Moreover, their peculiar chemical properties can sometimes give rise to unconventional superconducting or magnetic ground states. In the current work, we present an in-depth analysis of single crystals of YHg 3 and LuHg 3 (Mg 3 Cd structure type, space group P 6 3 / mmc ). Both compounds show superconductivity below T c = 1 ± 0.1 K (YHg 3 ) and T c = 1.2 ± 0.1 K (LuHg 3 ). Given the high air-sensitivity and toxicity of these compounds, this study was only possible using a number of dedicated experimental techniques., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Metal acetylacetonates of the general formula [M(acac) 3 ] (M III =Cr, Mn, Fe, Co) are among the best investigated coordination compounds. Many of these first-row transition metal complexes are known to have unique electronic properties. Independently, photophysical research with different β-diketonate ligands pointed towards the possibility of a special effect of the 2,4,6-trimethylphenyl substituted acetylacetonate (mesacac) on the electron distribution between ligand and metal (MLCT). We therefore synthesized and fully characterized the previously unknown octahedral title complex. Its solid-state structure shows a Jahn-Teller elongation with two Mn-O bonds of 2.12/2.15 Å and four Mn-O bonds of 1.93 Å. Thermogravimetric data show a thermal stability up to 270 °C. High-resolution mass spectroscopy helped to identify the decomposition pathways. The electronic state and spin configuration of manganese were characterized with a focus on its magnetic properties by measurement of the magnetic susceptibility and triple-zeta density functional theory (DFT) calculations. The high-spin state of manganese was confirmed by the determination of an effective magnetic moment of 4.85 μ B for the manganese center., (© 2022 The Authors. ChemPhysChem published by Wiley-VCH GmbH.)

In the phase diagram U-Cd, only one compound has been identified so far─UCd 11 (space group Pm 3̅ m ). Since the discovery of this material, the physical properties of UCd 11 have attracted a considerable amount of attention. In particular, its complex magnetic phase diagram─as a result of tuning with magnetic field or pressure─is not well-understood. From a chemical perspective, a range of lattice parameter values have been reported, suggesting a possibility of a considerable homogeneity range, i.e. , UCd 11-x . In this work, we perform a simultaneous study of crystallographic features coupled with measurements of physical properties. This work sheds light on the delicate relationship between the intrinsic crystal chemistry and magnetic properties of UCd 11 .

The underlying reasons for the catalytic activity of Ga 1-x Sn x Pd 2 (0 ≤ x ≤ 1) in the semi-hydrogenation of acetylene are analyzed considering electronic structure and chemical bonding. Analysis of the chemical bonding shows pronounced charge transfer from the p elements to palladium and an unusual appearance of the Pd core basins at the surface of the QTAIM (quantum theory of atoms in molecules) atoms. The charge transfer supports the formation of the negatively charged palladium catalytic centers. Gallium-only-coordinated palladium atoms reveal a smaller effective charge in comparison with palladium species having tin in their coordination sphere. Within the empirical tight-binding approach, different influence of the E-Pd distances on the calculation matrix for the energy eigenvalues and the electronic density of states (DOS) leads to an S-like shape of the plot of the energy position of the 4d band center of gravity versus substitution level x. The latter correlates strongly with the catalytic activity and with the varying charge transfer to palladium. The optimal value of negative palladium charge and the closest position of Pd d-states gravity center towards the Fermi level correlates well with the catalytically most active composition x. Combination of all features of the chemical bonding and electronic structure allows more insight into the intrinsic reasons for the catalytic activity variation in the platform material Ga 1-x Sn x Pd 2 (0 ≤ x ≤ 1)., (© 2022 The Authors. Published by Wiley-VCH GmbH.)

Mg 29- x Pt 4+ y represents the family of complex intermetallic compounds (complex metallic alloys, CMAs). It crystallizes in the cubic non-centrosymmetric space group F 4̅3 m with a = 20.1068(2) Å and around 400 atoms in a predominantly ordered arrangement. The local disorder around the unit cell origin is experimentally resolved by single-crystal X-ray diffraction in combination with atomic-resolution transmission electron microscopy (TEM, high-angle dark-field scanning TEM) studies. The quantum theory of atoms in molecules-based analysis of atomic charges shows that the unusual mixed Mg/Pt site occupation around the origin results from local charge equilibration in this region of the crystal structure. Chemical bonding analysis reveals for Mg 29- x Pt 4+ y ─rather unexpected for a crystal structure of this size─space-separated regions of hetero- and homoatomic bonds involving three to six partners (bonding inhomogeneity). Pt-containing 11- and 13-atomic units formed by heteroatomic 3 a -, 4 a -, and 5 a -bonds are condensed via edges and faces to large super-tetrahedrons, which are interlinked by Mg-only 6 a -bonds. Spatial separation of the regions with different bonding features is the key difference between the title compound and other CMAs, which are characterized by a predominantly homogeneous distribution of heteroatomic bonds.

The influence of structural disorder on superconductivity is not yet fully understood. A concurrent examination of crystallographic and physical properties of LaHg 6.4 reveals that this material enters a superconducting state below T c = 2.4 K while showing crystallographic disorder in one dimension. Lanthanum mercuride, which crystallizes in a new structure type (space group Cmcm , a = 9.779(2) Å, b = 28.891(4) Å, c = 5.0012(8) Å, Z = 8), has remained out of reach for nearly 50 years. In this crystal structure, strong disorder is present in the channels that propagate along the [001] direction. By implementing a combination of cutting-edge synthesis and characterization techniques, we were able to circumvent the complexity associated with the low formation temperature and chemical reactivity of this substance and study the superconductivity of LaHg 6.4 in detail.

Finding a way to interlink heat transport with the crystal structure and order/disorder phenomena is crucial for designing materials with ultralow lattice thermal conductivity. Here, we revisit the crystal structure and explore the thermoelectric properties of several compounds from the family of the filled β-Mn-type phases M 2/ n n + Ga 6 Te 10 ( M = Pb, Sn, Ca, Na, Na + Ag). The strongly disturbed thermal transport observed in the investigated materials originates from a three-dimensional Te-Ga network with lone-pair-like interactions, which results in large variations of the Ga-Te and M -Te interatomic distances and substantial anharmonic effects. In the particular case of NaAgGa 6 Te 10 , the additional presence of different cations leads to bonding inhomogeneity and strong structural disorder, resulting in a dramatically low lattice thermal conductivity (∼0.25 Wm -1 K -1 at 298 K), being the lowest among the reported β-Mn-type phases. This study offers a way to develop materials with ultralow lattice thermal conductivity by considering bonding inhomogeneity and lone-pair-like interactions., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The new phase Be 3 Ru crystallizes with TiCu 3 -type structure (space group Pmmn (59), a=3.7062(1) Å, b=4.5353(1) Å, c=4.4170(1) Å), a coloring variant of the hexagonal closest packing (hcp) of spheres. The electronic structure revealed that Be 3 Ru has a pseudo-gap close to the Fermi level. A strong charge transfer from Be to Ru was observed from the analysis of electron density within the Quantum Theory of Atoms in Molecules (QTAIM) framework and polar three- and four-atomic Be-Ru bonds were observed from the ELI-D (electron localizability indicator) analysis. This situation is very similar to the recently investigated Be 5 Pt and Be 21 Pt 5 compounds. The unusual crystal chemical feature of Be 3 Ru is that different charged species belong to the same closest packing, contrary to typical inorganic compounds, where the cationic components are located in the voids of the closest packing formed by anions. Be 3 Ru is a diamagnet displaying metallic electrical resistivity., (© 2022 The Authors. Published by Wiley-VCH GmbH.)

Efficient development of catalytic materials requires knowledge of the decisive parameters defining the catalytic properties. In multicomponent metallic catalysts, these are categorized as electronic and geometric effects, yet they are strongly interrelated. A systematic disentanglement can be achieved by fixing one parameter while altering the other, which becomes possible through the substitution in isostructural intermetallic compounds. This approach enables the evaluation of electronic or geometric contributions both individually and combined. Herein, this is achieved by substitution of indium (three valence electrons) with tin (four valence electrons) in the series In 1- x Sn x Pd 2 , which allows for a systematic variation of the total number of electrons per unit cell with only a minor variation of the unit cell parameters and thus the evaluation of the electronic effect. Geometric effects were evaluated by substitution of indium with gallium in the Ga 1- x In x Pd 2 series, which allows for a systematic variation of the interatomic distances while maintaining the same number of valence electrons per unit cell and close atomic coordinates. By substituting gallium with tin in the Ga 1- x Sn x Pd 2 series, both effects are combined and addressed simultaneously. The activity enhancement of the methanol oxidation reaction on the Ga 1- x Sn x Pd 2 series is attributed to the synergy of the combined effects.

Mg 3- x Ga 1+ x Ir ( x = 0.05) was synthesized by direct reaction of the elements in welded tantalum containers at 1200 °C and subsequent annealing at 500 °C for 30 days. Its crystal structure represents a new prototype and was determined by single-crystal technique as follows: space group P 6 3 / mcm , Pearson symbol hP 90, Z = 18, a = 14.4970(3) Å, c = 8.8638(3) Å. The composition and atomic arrangement in Mg 3 GaIr do not follow the 8- N rule due to the lack of valence electrons. Based on chemical bonding analysis in positional space, it was shown that the title compound has a polycationic-polyanionic organization. In comparison with other known intermetallic substances with this kind of bonding pattern, both the polyanion and the polyanion are remarkably complex. Mg 3- x Ga 1+ x Ir is an example of how the general organization of intermetallic substances (e.g., formation of polyanions and polycations) can be understood by extending the principles of 8- N compounds to electron-deficient materials with multi-atomic bonding.

Half-Heusler and full-Heusler compounds were considered as independent phases with a natural composition gap. Here we report the discovery of TiRu 1+x Sb (x = 0.15 ~ 1.0) solid solution with wide homogeneity range and tunable p- to n-type semiconducting thermoelectrics, which bridges the composition gap between half- and full-Heusler phases. At the high-Ru end, strange glass-like thermal transport behavior with unusually low lattice thermal conductivity (~1.65 Wm -1 K -1 at 340 K) is observed for TiRu 1.8 Sb, being the lowest among reported half-Heusler phases. In the composition range of 0.15 < x < 0.50, TiRu 1+x Sb shows abnormal semiconducting behaviors because tunning Ru composition results in band structure change and carrier-type variation simultaneously, which seemingly correlates with the localized d electrons. This work reveals the possibility of designing fascinating half-Heusler-like materials by manipulating the tetrahedral site occupancy, and also demonstrates the potential of tuning crystal and electronic structures simultaneously to realize intriguing physical properties., (© 2022. The Author(s).)

Unconventional superconductivity in non-centrosymmetric superconductors has attracted a considerable amount of attention. While several lanthanide-based materials have been reported previously, the number of actinide-based systems remains small. In this work, we present the discovery of a novel cubic complex non-centrosymmetric superconductor [Formula: see text] ([Formula: see text] space group). This intermetallic cage compound displays superconductivity below [Formula: see text] K, as evidenced by specific heat and resistivity data. [Formula: see text] is a type-II superconductor, which has an upper critical field [Formula: see text] T and a moderate Sommerfeld coefficient [Formula: see text] mJ [Formula: see text] [Formula: see text]. A non-zero density of states at the Fermi level is evident from metallic behavior in the normal state, as well as from electronic band structure calculations. The isostructural [Formula: see text] compound is a paramagnet with a moderately enhanced electronic mass, as indicated by the electronic specific heat coefficient [Formula: see text] mJ [Formula: see text] [Formula: see text] and Kadowaki-Woods ratio [Formula: see text] [Formula: see text] [Formula: see text] cm [Formula: see text] [Formula: see text] (mJ)[Formula: see text]. Both [Formula: see text] and [Formula: see text] are crystallographically complex, each hosting 212 atoms per unit cell., (© 2021. The Author(s).)

An implementation of the Interacting Quantum Atoms method for crystals is presented. It provides a real space energy decomposition of the energy of crystals in which all energy components are physically meaningful. The new package ChemInt enables one to compute intra-atomic and inter-atomic energies, as well as electron population measures used for quantitative description of chemical bonds in crystals. The implementation is tested and applied to characteristic molecular and crystalline systems with different types of bonding.

In a joint effort utilizing modified sample preparation, microscopy, X-ray diffraction and micro-fabrication, it became possible to prepare single crystals of the "hidden" phase AlCr 2 . High-resolution X-ray diffraction analysis is described in detail for two crystals with the similar overall composition, but different degree of disorder, which seems to be the main cause for the differing unit cell parameters. Chemical bonding analysis of AlCr 2 in comparison to prototypical MoSi 2 shows pronounced differences reflecting the interchange of main group element vs. transition metal as majority component., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The compound IrGa 3 was synthesized by direct reaction of the elements. It is formed as a high-temperature phase in the Ir-Ga system. Single-crystal X-ray diffraction analysis confirms the tetragonal symmetry (space group P 4 2 /mnm , No. 136) with a = 6.4623(1) Å and c = 6.5688(2) Å and reveals strong disorder in the crystal structure, reflected in the huge values and anisotropy of the atomic displacement parameters. A model for the real crystal structure of ht -IrGa 3 is derived by the split-position approach from the single-crystal X-ray diffraction data and confirmed by an atomic-resolution transmission electron microscopy study. Temperature-dependent electrical resistivity measurements evidence semiconductor behavior with a band gap of 30 meV. A thermoelectric characterization was performed for ht -IrGa 3 and for the solid solution IrGa 3- x Zn x ., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

The metastable type-II clathrate Na 24-δ Ge 136 was obtained from Na 12 Ge 17 by applying a two-step procedure. At first, Na 12 Ge 17 was reacted at 70 °C with a solution of benzophenone in the ionic liquid (IL) 1,3-dibutyl-2-methylimidazolium-bis(trifluoromethylsulfonyl) azanide. The IL was inert towards Na 12 Ge 17 , but capable of dissolving the sodium salts formed in the redox reaction. By annealing at 340 °C under an argon atmosphere, the X-ray amorphous intermediate product was transformed to crystalline Na 24-δ Ge 136 (δ≈2) and α-Ge in an about 1 : 1 mass ratio. The product was characterized by X-ray powder diffraction, chemical analysis, and 23 Na solid-state NMR spectroscopy. Metallic properties of Na 24-δ Ge 136 were revealed by a significant Knight shift of the 23 Na NMR signals and by a Pauli-paramagnetic contribution to the magnetic susceptibility. At room temperature, Na 24-δ Ge 136 slowly ages, with a tendency to volume decrease and sodium loss., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The binary phase Mg 3 Pt 2 was prepared by direct reaction between the elements or by spark-plasma synthesis starting with MgH 2 and PtCl 2 . The compound crystallizes in the monoclinic space group C 2/ c with a = 7.2096(3) Å, b = 7.1912(4) Å, c = 6.8977(3) Å, and β = 106.072(3)° and is isotypic to Eu 3 Ga 2 . Analysis of the electron density within the quantum theory of atoms in molecules shows a significant charge transfer from Mg to Pt in agreement with the electronegativity difference. Further study of the chemical bonding with the electron localizability approach reveals the formation of Pt chains stabilized by a complex system of multicenter interactions involving Mg and Pt species. The metallic character of Mg 3 Pt 2 is confirmed by electronic structure calculations and physical measurements.