studies of reversible solid-gas reactions of ethylene responsive silver pyrazolates.

Solid-gas reactions and powder X-ray diffraction investigations of trinuclear silver complexes {[3,4,5-(CF)Pz]Ag} and {[4-Br-3,5-(CF)Pz]Ag} supported by highly fluorinated pyrazolates reveal that they undergo intricate ethylene-triggered structural transformations in the solid-state producing dinuclear silver-ethylene adducts. Despite the complexity, the chemistry is reversible producing precursor trimers with the loss of ethylene. Less reactive {[3,5-(CF)Pz]Ag} under ethylene pressure and low-temperature conditions stops at an unusual silver-ethylene complex in the trinuclear state, which could serve as a model for intermediates likely present in more common trimer-dimer reorganizations described above.

Cation Adaptive Structures Based on Manganese Cyanide Prussian Blue Analogues: Application of Powder Diffraction Data to Solve Complex, Unprecedented Stoichiometries and New Structure Types.

A Mn(II) salt and A CN under anaerobic conditions react to form 2-D and 3-D extended structured compounds of A Mn (CN) stoichiometry. Here, the creation and characterization of this large family of compounds, for example AMn (CN) , A Mn (CN) , A Mn (CN) , A Mn (CN) , and A Mn [Mn (CN) ], where A represents alkali and tetraalkylammonium cations, is reviewed. Cs Mn [Mn (CN) ] has the typical Prussian blue face centered cubic unit cell.

A Molecular Compound for Highly Selective Purification of Ethylene.

Purification of C H from an C H /C H mixture is one of the most challenging separation processes, which is achieved mainly through energy-intensive, cryogenic distillation in industry. Sustainable, non-distillation methods are highly desired as alternatives. We discovered that the fluorinated bis(pyrazolyl)borate ligand supported copper(I) complex {[(CF ) Bp]Cu} has features very desirable in an olefin-paraffin separation material.

Ferrimagnetic Ordering and Anomalous Stoichiometry Observed for the Cubic, Extended 3D Prussian Blue Analogues (NEt Me) Mn (CN) and (NEt Me ) Mn (CN) : A Cation-Adaptive Structure.

The reactions of Mn (O CCH ) with NEt Me CN and NEt Me CN form (NEt Me) Mn (CN) (1) and (NEt Me ) Mn (CN) (2), respectively. Structure model-building and Rietveld refinement of high-resolution synchrotron powder diffraction data revealed a cubic [a=24.0093 Å (1), 23.

Acridine form IX.

We report a new polymorph of acridine, CHN, denoted form IX, obtained as thin needles by slow evaporation of a toluene solution. The structure was solved and refined from powder X-ray data. The structures of five unsolvated forms were previously known, but this is only the second with one mol-ecule in the asymmetric unit.

Anomalous Stoichiometry, 3-D Bridged Triangular/Pentagonal Layered Structured Artificial Antiferromagnet for the Prussian Blue Analogue AMn(CN) (A = NMe, NEtMe). A Cation Adaptive Structure.

The size of the organic cation dictates both the composition and the extended 3-D structure for hybrid organic/inorganic Prussian blue analogues (PBAs) of A Mn (CN) (A = cation) stoichiometry. Alkali PBAs are typically cubic with both MC and M'N octahedral coordination sites and the alkali cation content depends on the M and M' oxidation states. The reaction of Mn(OCCH) and ACN (A = NMe, NEtMe) forms a hydrated material of AMn(CN) composition.

Hydrating the Bispropionate Notch in Malaria Pigment: A New Structural Motif in the Iron(III)(deuteroporphyrin) Dimer.

Treating deuterohemin, chloro(deuteroporphyrinato)iron(III), with a non-coordinating base in DMSO/methanol allows for the isolation of [(deuteroporphyrinato)iron(III)] , deuterohematin anhydride (DHA), an analogue of malaria pigment, the natural product of heme detoxification by malaria. The structure of DHA obtained from this solvent system has been solved by X-ray powder diffraction analysis and displays many similarities, yet important structural differences, to malaria pigment. Most notably, a water molecule of solvation occupies a notch created by the propionate side chains and stabilizes a markedly bent propionate ligand coordinated with a long Fe-O bond, and a carboxylate cluster associated with water molecules is generated.

Anomalous Stoichiometry and Antiferromagnetic Ordering for the Extended Hydroxymanganese(II) Cubes/Hexacyanometalate-Based 3D-Structured [Mn (OH) ][Mn (CN) ](OH ) ⋅H O.

The reaction of Mn (O CMe) and NaCN or LiCN in water forms a light green insoluble material. Structural solution and Rietveld refinement of high-resolution synchrotron powder diffraction data for this unprecedented, complicated compound of previously unknown composition revealed a new alkali-free ordered structural motif with [Mn (μ -OH) ] cubes and octahedral [Mn (CN) ] ions interconnected in 3D by Mn -N≡C-Mn linkages. The composition is {[Mn (OH ) ][Mn (OH )] }(μ -OH) ][Mn (μ-CN) (CN) ]⋅H O=[Mn (μ -OH) (OH ) ][Mn (μ-CN) (CN) ]⋅H O, which is further simplified to [Mn (OH) ][Mn(CN) ](OH ) (1).

Magnetostriction-polarization coupling in multiferroic MnMnWO.

Double corundum-related polar magnets are promising materials for multiferroic and magnetoelectric applications in spintronics. However, their design and synthesis is a challenge, and magnetoelectric coupling has only been observed in NiTeO among the known double corundum compounds to date. Here we address the high-pressure synthesis of a new polar and antiferromagnetic corundum derivative MnMnWO, which adopts the NiTeO-type structure with low temperature first-order field-induced metamagnetic phase transitions (T  = 58 K) and high spontaneous polarization (~ 63.

Ba(CrTe)TeO: in Search of Jahn-Teller Distorted Cr(II) Oxide.

A novel 6H-type hexagonal perovskite Ba(CrTe)TeO was prepared at high pressure (6 GPa) and temperature (1773 K). Both transmission electron microscopy and synchrotron powder X-ray diffraction data demonstrate that Ba(CrTe)TeO crystallizes in P6/mmc with face-shared (CrTe)O octahedral pairs interconnected with TeO octahedra via corner-sharing. Structure analysis shows a mixed Cr/Cr valence state with ∼10% Cr.

Low-Temperature Cationic Rearrangement in a Bulk Metal Oxide.

Cationic rearrangement is a compelling strategy for producing desirable physical properties by atomic-scale manipulation. However, activating ionic diffusion typically requires high temperature, and in some cases also high pressure in bulk oxide materials. Herein, we present the cationic rearrangement in bulk Mn2 FeMoO6 at unparalleled low temperatures of 150-300 (o) C.

Pb2MnTeO6 Double Perovskite: An Antipolar Anti-ferromagnet.

Pb2MnTeO6, a new double perovskite, was synthesized. Its crystal structure was determined by synchrotron X-ray and powder neutron diffraction. Pb2MnTeO6 is monoclinic (I2/m) at room temperature with a regular arrangement of all the cations in their polyhedra.

Combined Theoretical and in Situ Scattering Strategies for Optimized Discovery and Recovery of High-Pressure Phases: A Case Study of the GaN-Nb2O5 System.

The application of pressure in solid-state synthesis provides a route for the creation of new and exciting materials. However, the onerous nature of high-pressure techniques limits their utility in materials discovery. The systematic search for novel oxynitrides-semiconductors for photocatalytic overall water splitting-is a representative case where quench high-pressure synthesis is useful and necessary in order to obtain target compounds.

Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX2(pyz)2 (X = Cl, Br, I, NCS; pyz = Pyrazine).

The crystal structures of NiX2(pyz)2 (X = Cl (1), Br (2), I (3), and NCS (4)) were determined by synchrotron X-ray powder diffraction. All four compounds consist of two-dimensional (2D) square arrays self-assembled from octahedral NiN4X2 units that are bridged by pyz ligands. The 2D layered motifs displayed by 1-4 are relevant to bifluoride-bridged [Ni(HF2)(pyz)2]EF6 (E = P, Sb), which also possess the same 2D layers.

Giant magnetoresistance in the half-metallic double-perovskite ferrimagnet Mn2FeReO6.

The first transition-metal-only double perovskite compound, Mn(2+) 2 Fe(3+) Re(5+) O6 , with 17 unpaired d electrons displays ferrimagnetic ordering up to 520 K and a giant positive magnetoresistance of up to 220 % at 5 K and 8 T. These properties result from the ferrimagnetically coupled Fe and Re sublattice and are affected by a two-to-one magnetic-structure transition of the Mn sublattice when a magnetic field is applied. Theoretical calculations indicate that the half-metallic state can be mainly attributed to the spin polarization of the Fe and Re sites.

Conformational isomerism in solid state of AMG 853--structure studies using solid-state nuclear magnetic resonance and X-ray diffraction.

Investigation of an additional resonance peak in the (19) F solid-state nuclear magnetic resonance (NMR) spectrum of AMG 853, a dual antagonist of DP and CRTH2 previously in clinical development for asthma, has led to the identification of two conformational isomers coexisting in the crystal lattice in a continuous composition range between 89.7%:10.3% and 96.

Mn2FeWO6 : A new Ni3TeO6-type polar and magnetic oxide.

Mn(2+)2 Fe(2+)W(6+)O6 , a new polar magnetic phase, adopts the corundum-derived Ni3TeO6 -type structure with large spontaneous polarization (PS) of 67.8 μC cm(-2), complex antiferromagnetic order below ≈75 K, and field-induced first-order transition to a ferrimagnetic phase below ≈30 K. First-principles calculations predict a ferrimagnetic (udu) ground state, optimal switching path along the c-axis, and transition to a lower energy udu-udd magnetic double cell.

Hole doping and structural transformation in CsTl1-xHgxCl3.

CsTlCl(3) and CsTlF(3) perovskites have been theoretically predicted to be superconductors when properly hole-doped. Both compounds have been previously prepared as pure compounds: CsTlCl(3) in a tetragonal (I4/m) and a cubic (Fm3̅m) perovskite polymorph and CsTlF(3) as a cubic perovskite (Fm3̅m). In this work, substitution of Tl in CsTlCl(3) with Hg is reported, in an attempt to hole-dope the system and induce superconductivity.

In situ non-aqueous nucleation and growth of next generation rare-earth-free permanent magnets.

Using a controllable wet chemical approach, the polyol process, we developed a cobalt carbide nanomagnet consisting of an assembly of Co2C and Co3C nanoparticles as an alternative to rare earth permanent magnets (PMs). The thermodynamically stable mixed phase cobalt carbide nanoparticles are shown to be acicular in morphology. Their exchange-coupled magnetic interaction possessing high maximum energy product of 20.

Ferromagnetic ordering in superatomic solids.

In order to realize significant benefits from the assembly of solid-state materials from molecular cluster superatomic building blocks, several criteria must be met. Reproducible syntheses must reliably produce macroscopic amounts of pure material; the cluster-assembled solids must show properties that are more than simply averages of those of the constituent subunits; and rational changes to the chemical structures of the subunits must result in predictable changes in the collective properties of the solid. In this report we show that we can meet these requirements.

Structure and properties of nitrogen-rich 1,4-dicyanotetrazine, C4N6: a comparative study with related tetracyano electron acceptors.

The crystal structure, redox electrochemical stability, and reaction chemistry of 1,4-dicyanotetrazine (DCNT) has been experimentally characterized. These experimental results were rationalized by the results of theoretical calculations of the electronic structure, spin and charge distributions, electronic absorption spectra, and electron affinity and compared with the results for related the tetracyano electron acceptors tetracyanoethylene (TCNE), 7,7,8,8-tetracyano-p-quinodimethane (TCNQ), and 2,3,5,6-tetracyanopyrazine (TCNP). DCNT is made from the dehydration of 1,2,4,5-tetrazine-3,6-dicarboxamide, and because of the unusual deep-magenta color of the dicarboxamide in the solid state, its hydrogen-bonded layered structure, electronic structure, and electronic absorption spectra were determined.