Magnesium(I) Reduction of Aluminum(III) Hydride Complexes: Generation of Mixed Valence Aluminum (Al /Al ) Hydride Cluster Compounds, [Al H (NR ) {Mg(β-diketiminate)} ].

Reduction of a range of amido- and aryloxy-aluminum dihydride complexes, e.g. [AlH (NR ){N(SiMe ) }] (NR =NMe or N-methylpiperidine (NMP)), with β-diketiminato dimagnesium(I) reagents, [{( Nacnac)Mg} ] ( Nacnac=[HC(MeCNAr) ] , Ar=mesityl (Mes) or 2,6-xylyl (Xyl)), have afforded deep red mixed valence aluminum hydride cluster compounds, [Al H (NR ) {Mg( Nacnac)} ], which have an average Al oxidation state of +0.

Synthesis of 12β-Methyl-18--bile Acids.

Decoupling the roles of the farnesoid X nuclear receptor and Takeda G-protein-coupled bile acid receptor 5 is essential for the development of novel bile acid therapeutics targeting metabolic and neurodegenerative diseases. Herein, we describe the synthesis of 12β-methyl-18--bile acids which may serve as probes in the search for new bile acid analogues with clinical applicability. A Nametkin-type rearrangement was applied to protected cholic acid derivatives, giving rise to tetra-substituted Δ- and Δ-unsaturated 12β-methyl-18--bile acid intermediates ( and ).

A Discrete Chloride Monohydrate: A Solid-State Structural and Spectroscopic Characterization.

The solid-state structure of a discrete chloride monohydrate species, [Cl(HO)], is reported for the first time. It was isolated as a salt of the tris(dipropylamino)cyclopropenium cation and has been structurally characterized by X-ray and neutron diffraction. Infrared (IR), far-infrared, and Raman spectroscopic studies were also carried out.

Molecular Thorium Trihydrido Clusters Stabilized by Cyclopentadienyl Ligands.

Hydrogenolysis of alkyl-substituted cyclopentadienyl (Cp ) ligated thorium tribenzyl complexes [(Cp )Th(p-CH -C H -Me) ] (1-6) afforded the first examples of molecular thorium trihydrido complexes [(Cp )Th(μ-H) ] (Cp =C H ( Bu) or C H (SiMe ) , n=5; C Me SiMe , n=6; C Me , n=7; C Me H, n=8; 7-10 and 12) and [(Cp ) Th H ] (Cp =C H SiMe ; 13). The nuclearity of the metal hydride clusters depends on the steric profile of the cyclopentadienyl ligands. The hydrogenolysis intermediate, tetra-nuclear octahydrido thorium dibenzylidene complex [(Cp )Th(μ-H) ] (μ-p-CH-C H -Me) (Cp =C H ( Bu) ) (11) was also isolated.

Investigation of an Unusual Crystal Habit of Hydrochlorothiazide Reveals Large Polar Enantiopure Domains and a Possible Crystal Nucleation Mechanism.

The observation of an unusual crystal habit in the common diuretic drug hydrochlorothiazide (HCT), and identification of its subtle conformational chirality, has stimulated a detailed investigation of its crystalline forms. Enantiomeric conformers of HCT resolve into an unusual structure of conjoined enantiomorphic twin crystals comprising enantiopure domains of opposite chirality. The purity of the domains and the chiral molecular conformation are confirmed by spatially revolved synchrotron micro-XRD experiments and neutron diffraction, respectively.

Mapping the Magnetic Anisotropy at the Atomic Scale in Dysprosium Single-Molecule Magnets.

The anisotropy of the magnetic properties of molecular magnets is a key descriptor in the search for improved magnets. Herein, it is shown how an analytical approach using single-crystal polarized neutron diffraction (PND) provides direct access to atomic magnetic susceptibility tensors. The technique was applied for the first time to two Dy-based single-molecule magnets and showed clear axial atomic susceptibility for both Dy ions.

Anion stabilised hypercloso-hexaalane AlH.

Boron hydride clusters are an extremely diverse compound class, which are of enormous importance to many areas of chemistry. Despite this, stable aluminium hydride analogues of these species have remained staunchly elusive to synthetic chemists. Here, we report that reductions of an amidinato-aluminium(III) hydride complex with magnesium(I) dimers lead to unprecedented examples of stable aluminium(I) hydride complexes, [(Nacnac)Mg][AlH(Fiso)] (Nacnac = [HC(MeCNAr)], Ar = CHMe-2,4,6 Mes; CHEt-2,6 Dep or CHMe-2,6 Xyl; Fiso = [HC(NDip)], Dip = CHPr-2,6), which crystallographic and computational studies show to possess near neutral, octahedral hypercloso-hexaalane, AlH, cluster cores.

Achirality in the low temperature structure and lattice modes of tris(acetylacetonate)iron(iii).

Tris(acetylacteonate) iron(iii) is a relatively ubiquitous mononuclear inorganic coordination complex. The bidentate nature of the three acetylacteonate ligands coordinating around a single centre inevitably leads to structural isomeric forms, however whether or not this relates to chirality in the solid state has been questioned in the literature. Variable temperature neutron diffraction data down to T = 3 K, highlights the dynamic nature of the ligand environment, including the motions of the hydrogen atoms.

Interstitial Oxide Ion Distribution and Transport Mechanism in Aluminum-Doped Neodymium Silicate Apatite Electrolytes.

Rare earth silicate apatites are one-dimensional channel structures that show potential as electrolytes for solid oxide fuel cells (SOFC) due to their high ionic conductivity at intermediate temperatures (500-700 °C). This advantageous property can be attributed to the presence of both interstitial oxygen and cation vacancies, that create diffusion paths which computational studies suggest are less tortuous and have lower activation energies for migration than in stoichiometric compounds. In this work, neutron diffraction of Nd(28+x)/3AlxSi6-xO26 (0 ≤ x ≤ 1.

Type II Bi1 - xWxO1.5 + 1.5x: a (3 + 3)-dimensional commensurate modulation that stabilizes the fast-ion conducting delta phase of bismuth oxide.

The Type II phase in the Bi1 - xWxO1.5 + 1.5x system is shown to have a (3 + 3)-dimensional modulated δ-Bi2O3-related structure, in which the modulation vector ℇ `locks in' to a commensurate value of 1/3.

Concerted mitigation of O···H and C(π)···H interactions prospects sixfold gain in optical nonlinearity of ionic stilbazolium derivatives.

DAST (4-dimethylamino-N-methyl-4-stilbazolium tosylate) is the most commercially successful organic nonlinear optical (NLO) material for frequency-doubling, integrated optics, and THz wave applications. Its success is predicated on its high optical nonlinearity with concurrent sufficient thermal stability. Many chemical derivatives of DAST have therefore been developed to optimize their properties; yet, to date, none have surpassed the overall superiority of DAST for NLO photonic applications.

Structural study of the apatite Nd₈Sr₂Si₆O₂₆ by Laue neutron diffraction and single-crystal Raman spectroscopy.

A single-crystal structure determination of Nd8Sr2Si6O26 apatite, a prototype intermediate-temperature electrolyte for solid oxide fuel cells grown by the floating-zone method, was completed using the combination of Laue neutron diffraction and Raman spectroscopy. While neutron diffraction was in good agreement with P6₃/m symmetry, the possibility of P6₃ could not be convincingly excluded. This ambiguity was removed by the collection of orientation-dependent Raman spectra that could only be consistent with P6₃/m.

Chinese puzzle molecule: a 15 hydride, 28 copper atom nanoball.

The syntheses of the first rhombicuboctahedral copper polyhydride complexes [Cu28 (H)15 (S2 CNR)12 ]PF6 (NR=N(n) Pr2 or aza-15-crown-5) are reported. These complexes were analyzed by single-crystal X-ray and one by neutron diffraction. The core of each copper hydride nanoparticle comprises one central interstitial hydride and eight outer-triangular-face-capping hydrides.

Scrutinizing negative thermal expansion in MOF-5 by scattering techniques and ab initio calculations.

Complementary experimental techniques and ab initio calculations were used to determine the origin and nature of negative thermal expansion (NTE) in the archetype metal-organic framework MOF-5 (Zn(4)O(1,4-benzenedicarboxylate)(3)). The organic linker was probed by inelastic neutron scattering under vacuum and at a gas pressure of 175 bar to distinguish between the pressure and temperature responses of the framework motions, and the local structure of the metal centers was studied by X-ray absorption spectroscopy. Multi-temperature powder- and single-crystal X-ray and neutron diffraction was used to characterize the polymeric nature of the sample and to quantify NTE over the large temperature range 4-400 K.

Reassessment of large dipole moment enhancements in crystals: a detailed experimental and theoretical charge density analysis of 2-methyl-4-nitroaniline.

The molecular dipole moment of MNA in the crystal has been critically reexamined, to test the conclusion from an earlier experimental charge density analysis that it was substantially enhanced due to a combination of strong intermolecular interactions and crystal field effects. X-ray and neutron diffraction data have been carefully measured at 100 K and supplemented with ab initio crystal Hartree-Fock calculations. Considerable care taken in the measurement and reduction of the experimental data excluded most systematic errors, and sources of error and their effects on the experimental electron density have been carefully investigated.

Experimental and theoretical charge distribution in (Z)-N-methyl-C-phenylnitrone.

The total experimental charge density in (Z)-N-methyl-C-phenylnitrone (1) has been determined using high-resolution X-ray diffraction data in combination with neutron diffraction data measured at 100 K in terms of the rigid pseudoatom model. Multipole refinement converged at R = 0.03 for 7163 reflections with I > 2 sigma(I).

X-N charge density analysis of the hydrogen bonding motif in 1-(2-hydroxy-5-nitrophenyl)ethanone.

The total experimental charge density in 1-(2-hydroxy-5-nitrophenyl)ethanone (1) has been determined using high-resolution X-ray diffraction data in combination with neutron diffraction data measured at 100 K. Multipole refinement was carried out in terms of the rigid pseudoatom model. Multipole refinement converged at R = 0.