Principles of weakly ordered domains in intermetallics: the cooperative effects of atomic packing and electronics in FeAl.

Many complex intermetallic structures feature a curious juxtaposition of domains with strict 3D periodicity and regions of much weaker order or incommensurability. This article explores the basic principles leading to such arrangements through an investigation of the weakly ordered channels of FeAl. It starts by experimentally confirming the earlier crystallographic model of the high-temperature form, in which nearly continuous columns of electron density corresponding to disordered Al atoms emerge.

Deciphering composition and connectivity of a natural product with the assistance of MS and 2D NMR.

A complementary application of three analytical techniques, viz. multidimensional nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS), and single-crystal X-ray diffractometry was required to identify and refine two natural products isolated from Millettia versicolor and solvent of crystallization. The two compounds, namely 3-(2H-1,3-benzodioxol-5-yl)-6-methoxy-8,8-dimethyl-4H,8H-pyrano[2,3-h]chromen-4-one, or durmillone, (I), and (2E)-1-(4-{[(2E)-3,7-dimethylocta-2,6-dien-1-yl]oxy}-2-hydroxyphenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one, (II), could not be separated by routine column chromatography and cocrystallized in a 2:1 ratio with 0.

Crystal structure of {()--[(benzo[]quinolin-2-yl)meth-yl]--[(benzo[]quinolin-2-yl)methyl-idene]-1,1'-binaphthyl-2,2'-di-amine-κ,','','''}(trifluoromethane-sulfonato-κ)zinc(II)} trifluoromethane-sulfonate di-chloro-methane 1.5-solvate.

The zinc(II) atom in the title compound, [Zn(CHN)(CFSO)](CFSO)·1.5CHCl, adopts a distorted five-coordinate square-pyramidal geometry. It is coordinated by one tri-fluoro-methane-sulfonate ligand and four N atoms of the -[(benzo[]quinolin-2-yl)meth-yl]--[(benzo[]quinolin-2-yl)methyl-idene]-1,1'-binaphthyl-2,2'-di-amine ligand.

Crystal structure of ({(1,2)-,'-bis-[(quino-lin-2-yl)methyl]cyclo-hexane-1,2-di-amine}-chlorido-iron(III))-μ-oxido-[tri-chlorido-ferrate(III)] chloro-form monosolvate.

The first Fe atom in the solvated title compound, [FeClO(CHN)]·CHCl, adopts a distorted six-coordinate octa-hedral geometry. It is coordinated by one chloride ligand, four N atoms from the (1,2)-,'-bis-[(quinolin-2-yl)methyl]cyclo-hexane-1,2-di-amine ligand, and a bridging oxido ligand attached to the second Fe atom, which is also bonded to three chloride ions. A very weak intra-molecular N-H⋯Cl hydrogen bond occurs.

Synthesis, Characterization, and Variable-Temperature NMR Studies of Silver(I) Complexes for Selective Nitrene Transfer.

An array of silver complexes supported by nitrogen-donor ligands catalyze the transformation of C═C and C-H bonds to valuable C-N bonds via nitrene transfer. The ability to achieve high chemoselectivity and site selectivity in an amination event requires an understanding of both the solid- and solution-state behavior of these catalysts. X-ray structural characterizations were helpful in determining ligand features that promote the formation of monomeric versus dimeric complexes.

18-Electron Resonance Structures in the BCC Transition Metals and Their CsCl-type Derivatives.

Bonding in elemental metals and simple alloys has long been thought of as involving intense delocalization, with little connection to the localized bonds of covalent systems. In this Article, we show that the bonding in body-centered cubic (bcc) structures of the group 6 transition metals can in fact be represented, via the concepts of the 18-n rule and isolobal bonding, in terms of two balanced resonance structures. We begin with a reversed approximation Molecular Orbital (raMO) analysis of elemental Mo in its bcc structure.

Toward Design Principles for Diffusionless Transformations: The Frustrated Formation of Co-Co Bonds in a Low-Temperature Polymorph of GdCoSi2.

Diffusionless (or displacive) phase transitions allow inorganic materials to show exquisite responsiveness to external stimuli, as is illustrated vividly by the superelasticity, shape memory, and magnetocaloric effects exhibited by martensitic materials. In this Article, we present a new diffusionless transition in the compound GdCoSi2, whose origin in frustrated bonding points toward generalizable design principles for these transformations. We first describe the synthesis of GdCoSi2 and the determination of its structure using single crystal X-ray diffraction.

Solubilities and Glass Formation in Aqueous Solutions of the Sodium Salts of Malonic Acid With and Without Ammonium Sulfate.

The solubility of sodium hydrogen malonate and sodium malonate in water both with and without ammonium sulfate present has been studied using differential scanning calorimetry and infrared spectroscopy. The crystals that form from sodium hydrogen malonate/water solutions were determined to be sodium hydrogen malonate monohydrate by single-crystal X-ray diffractometry. The crystals formed in sodium malonate/water solutions were determined to be sodium malonate monohydrate, a compound whose structure had not been previously known.

How Lewis acidity of the cationic framework affects KNaNbOF(5) polymorphism.

The valence matching principle is used to explain the loss of inversion symmetry in the noncentrosymmetric (NCS) polymorph of KNaNbOF5 in comparison to its centrosymmetric (CS) polymorph. The [NbOF5](2-) anion has five contacts to both potassium and sodium in the NCS polymorph, whereas in the CS polymorph there are only four contacts to potassium and six contacts to sodium. The lower average Lewis acidity of the cationic framework in the NCS polymorph relative to the CS polymorph reflects the loss of inversion symmetry.