Chemical Pressure-Driven Incommensurability in CaPd5: Clues to High-Pressure Chemistry Offered by Complex Intermetallics.

While composition and pressure are generally considered orthogonal parameters in the synthesis and optimization of solid state materials, their distinctness is blurred by the concept of chemical pressure (CP): microscopic pressure arising from lattice constraints rather than an externally applied force. In this article, we describe the first cycle of an iterative theoretical/experimental investigation into this connection. We begin by theoretically probing the ability of physical pressure to promote structural transitions in CaCu5-type phases that are driven by CP in other systems.

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).

Homoatomic clustering in T4Ga5 (T = Ta, Nb, Ta/Mo): a story of reluctant intermetallics crystallizing in a new binary structure type.

In the formation of binary compounds, heteroatomic interactions are generally expected to play the leading role in providing stability. In this Article, we present a series of gallides, T(4)Ga(5) (T = Ta, Nb, and Ta/Mo), which appear to defy this expectation. Their complex crystal structures represent a new binary structure type (to the best of our knowledge),, which can be visualized in terms of a host lattice of T@T(8) body centered cubic (bcc) clusters linked through face-capping Ga(2) dumbbells to form a primitive cubic framework.

Progress in Visualizing Atomic Size Effects with DFT-Chemical Pressure Analysis: From Isolated Atoms to Trends in AB5 Intermetallics.

The notion of atomic size poses an important challenge to chemical theory: empirical evidence has long established that atoms have spatial requirements, which are summarized in tables of covalent, ionic, metallic, and van der Waals radii. Considerations based on these radii play a central role in the design and interpretation of experiments, but few methods are available to directly support arguments based on atomic size using electronic structure methods. Recently, we described an approach to elucidating atomic size effects using theoretical calculations: the DFT-Chemical Pressure analysis, which visualizes the local pressures arising in crystal structures from the interactions of atomic size and electronic effects.

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.

Heterometallic architectures based on the combination of heteroleptic copper and cobalt complexes with silver salts.

A strategy for the formation of heterometallic coordination polymers based on novel copper(II) and cobalt(III) heteroleptic complexes (acacCN)Cu(dpm) and (acacCN)Co(dpm)(2) (acacCN = 3-cyanoacetylacetonate; dpm = dipyrrin) is presented. Using dipyrrins appended with a p- or m-pyridyl group, dpm-4py and dpm-3py, four novel copper and cobalt complexes were prepared and characterized both in solution and in the solid state. These two classes of complexes show different electrochemical properties upon investigation by cyclic voltammetry in CH(2)Cl(2).