Evolution of Bonding and Magnetism Changes in Valence Electron Count in CuFeCoGe.

A series of solid solutions, CuFeCoGe ( = 0, 0.2, 0.4, 0.

At the Limits of Isolobal Bonding: π-Based Covalent Magnetism in MnHg.

Magnetic ordering in inorganic materials is generally considered to be a mechanism for structures to stabilize open shells of electrons. The intermetallic phase MnHg represents a remarkable exception: its crystal structure is in accordance with the 18- bonding scheme and non-spin-polarized density functional theory (DFT) calculations show a corresponding pseudogap near its Fermi energy. Nevertheless, it exhibits strong antiferromagnetic ordering virtually all the way up to its decomposition temperature.

NaMnSe: Strongly Frustrated Antiferromagnetic Semiconductor with Complex Magnetic Structure.

A new ternary selenide, NaMnSe, was prepared by a stoichiometric reaction between NaSe and metallic Mn at 923 K. Crystal structure determination revealed a new structure type, built of alternating layers of Na ions and [MnSe] anionic slabs. Band structure calculations indicate that NaMnSe is an indirect band gap semiconductor with E = 1.

Electrocatalytic water oxidation over AlFeB.

We report excellent electrocatalytic performance by AlFeB in the oxygen-evolution reaction (OER). The inexpensive catalytic material, prepared simply by arc-melting followed by ball-milling, exhibits high stability and sustained catalytic performance under alkaline conditions. The overpotential value of 0.

Revisiting Bond Breaking and Making in EuCo P : Where are the Electrons?

X-ray absorption spectroscopy (XAS) was used to elucidate changes in the electronic structure caused by the pressure-induced structural collapse in EuCo P . The spectral changes observed at the L -edge of Eu and K-edges of Co and P suggest electron density redistribution, which contradicts the formal charges calculated from the commonly used Zintl-Klemm concept. Quantum-chemical calculations show that, despite the increase in the oxidation state of Eu and the formation of a weak P-P bond in the high-pressure phase, the electron transfer from the Eu 4f orbitals to the hybridized 5d and 6s states causes strengthening of the Eu-P and P-P bonds.

Inducing Complexity in Intermetallics through Electron-Hole Matching: The Structure of Fe Pd Al.

We illustrate how the crystal structure of Fe Pd Al provides an example of an electron-hole matching approach to inducing frustration in intermetallic systems. Its structure contains a framework based on IrAl , a binary compound that closely adheres to the 18-n rule. Upon substituting the Ir with a mixture of Fe and Pd, a competition arises between maintaining the overall ideal electron concentration and accommodating the different structural preferences of the two elements.

Generality of the 18-n Rule: Intermetallic Structural Chemistry Explained through Isolobal Analogies to Transition Metal Complexes.

Intermetallic phases exhibit a vast structural diversity in which electron count is known to be one controlling factor. However, chemical bonding theory has yet to establish how electron counts and structure are interrelated for the majority of these compounds. Recently, a simple bonding picture for transition metal (T)-main group (E) intermetallics has begun to take shape based on isolobal analogies to molecular T complexes.

Defusing Complexity in Intermetallics: How Covalently Shared Electron Pairs Stabilize the FCC Variant Mo2Cu(x)Ga(6-x) (x ≈ 0.9).

Simple sphere packings of metallic atoms are generally assumed to exhibit highly delocalized bonding, often visualized in terms of a lattice of metal cations immersed in an electron gas. In this Article, we present a compound that demonstrates how covalently shared electron pairs can, in fact, play a key role in the stability of such structures: Mo2Cu(x)Ga(6-x) (x ≈ 0.9).

Orbital origins of helices and magic electron counts in the Nowotny chimney ladders: the 18 - n rule and a path to incommensurability.

Valence electron count is one of the key factors influencing the stability and structure of metals and alloys. However, unlike in molecular compounds, the origins of the preferred electron counts of many metallic phases remain largely mysterious. Perhaps the clearest-cut of such electron counting rules is exhibited by the Nowotny chimney ladder (NCL) phases, compounds remarkable for their helical structural motifs in which transition metal (T) helices serve as channels for a second set of helices formed from main group (E) elements.

π-Conjugation in Gd13Fe10C13 and its oxycarbide: unexpected connections between complex carbides and simple organic molecules.

Carbometalates are a diverse family of solid state structures formed from transition metal (TM)-carbon polyanionic frameworks whose charges are balanced by rare earth (RE) cations. Remarkable structural features, such as transition metal clusters, are often encountered in these phases, and a pressing challenge is to explain how such features emerge from the competing interaction types (RE-TM, TM-TM, TM-C, etc.) in these systems.

Isolobal analogies in intermetallics: the reversed approximation MO approach and applications to CrGa4- and Ir3Ge7-type phases.

Intermetallic phases offer a wealth of unique and unexplained structural features, which pose exciting challenges for the development of new bonding concepts. In this article, we present a straightforward approach to rapidly building bonding descriptions of such compounds: the reversed approximation Molecular Orbital (raMO) method. In this approach, we reverse the usual technique of using linear combinations of simple functions to approximate true wave functions and employ the fully occupied crystal orbitals of a compound as a basis set for the determination of the eigenfunctions of a simple, chemically transparent model Hamiltonian.