A Porous Chalcogen-Bonded Organic Framework.

The manner of bonding between constituent atoms or molecules invariably influences the properties of materials. Perhaps no material family is more emblematic of this than porous frameworks, wherein the namesake modes of connectivity give rise to discrete subclasses with unique collections of properties. However, established framework classes often display offsetting advantages and disadvantages for a given application.

New Solids in As-O-Mo, As(P)-O-Mo(W) and As(P)-O-Nb(W) Systems That Exhibit Nonlinear Optical Properties.

Interactions between well-mixed fine powders of AsO, PO, MoO, WO and NbO at different stoichiometry in quartz ampoules under vacuum at ~1000 °C in the presence of metallic molybdenum (or niobium), over several weeks, led to shiny dichroic crystalline materials being formed in cooler parts of the reaction vessel. An addition of small quantities of metals-Mo or Nb-was made with the aim of partially reducing their highly oxidized Mo(VI), W(VI) or Nb(V) species to corresponding Mo(V), W(V) and Nb(IV) centers, in order to form mixed valence solids. Sublimed crystals of four new compounds were investigated using a variety of techniques, with prime emphasis on the X-ray analysis, followed by spectroscopy (diffusion reflectance, IR, Raman and EPR), second harmonic generation (SHG), thermal analysis under N and air atmosphere, and single crystals electrical conductivity studies.

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.

Mechanochemical routes for the synthesis of acetyl- and bis-(imino)pyridine ligands and organometallics.

Organometallic precatalysts play a pivotal role in organic synthesis. However, their preparation often relies on multiple time, energy, and solvent intensive steps, including the synthesis of supporting organic ligand structures, and finally installation on the desired metal centres. We report the sustainable mechanochemical synthesis of acetyl- and bis-(imino)pyridine pincer complexes, a ubiquitous ligand class for organometallic precatalysts.

Correction: An electron transfer driven magnetic switch: ferromagnetic exchange and spin delocalization in iron verdazyl complexes.

Correction for 'An electron transfer driven magnetic switch: ferromagnetic exchange and spin delocalization in iron verdazyl complexes' by David J. R. Brook et al.

An electron transfer driven magnetic switch: ferromagnetic exchange and spin delocalization in iron verdazyl complexes.

The verdazyl 'pincer' ligand, 1-isopropyl-3,5-dipyridyl-6-oxoverdazyl (dipyvd), coordinates iron to form a series of pseudooctahedral coordination compounds [Fe(dipyvd)2]n+ (n = 0-3). In the case where n = 2, the molecular geometry and physical and spectral properties are consistent with a low spin (S = 0) iron(ii) ion coordinated by two ferromagnetically coupled radical ligands. Upon one electron reduction, the room temperature effective magnetic moment of the complex jumps from μeff = 2.

Implications of bond disorder in a S=1 kagome lattice.

Strong hydrogen bonds such as F···H···F offer new strategies to fabricate molecular architectures exhibiting novel structures and properties. Along these lines and, to potentially realize hydrogen-bond mediated superexchange interactions in a frustrated material, we synthesized [HF][NiF(Fpy)][SbF] (Fpy = 3-fluoropyridine). It was found that positionally-disordered HF ions link neutral NiF(Fpy) moieties into a kagome lattice with perfect 3-fold rotational symmetry.

Hydrogen-Bonding Effects in Five-Coordinate High-Spin Imidazole-Ligated Iron(II) Porphyrinates.

The influence of hydrogen binding to the N-H group of coordinated imidazole in high-spin iron(II) porphyrinates has been studied. The preparation and characterization of new complexes based on [Fe(TPP)(2-MeHIm)] (TPP is the dianion of tetraphenylporphyrin) are reported. The hydrogen bond acceptors are ethanol, tetramethylene sulfoxide, and 2-methylimidazole.

Incommensurate density modulation in a Na-rich plagioclase feldspar: Z-contrast imaging and single-crystal X-ray diffraction study.

Plagioclase feldspars are the most abundant mineral in the Earth's crust. Intermediate plagioclase feldspars commonly display incommensurately modulated or aperiodic structures. Z-contrast images show both Ca-Na ordering and density modulation.

C(sp )-H Oxidative Addition and Transfer Hydrogenation Chemistry of a Titanium(II) Synthon: Mimicry of Late-Metal Type Reactivity.

Two-electron reduction of the Ti compound ( guan)(Im N)Ti(OTf) (3) gives the arene-masked complex ( guan)(η -Im N)Ti (1) in excellent yield. Upon standing in solution, 1 converts to a Ti metallacycle (4) through dehydrogenation of a pendant isopropyl group. Spectroscopic evidence shows this transformation initially proceeds via the oxidative addition of a C(sp )-H bond and can be reversed upon exposure of 4 to H .

Chemical Stabilization and Electrochemical Destabilization of the Iron Keggin Ion in Water.

The iron Keggin ion is identified as a structural building block in both magnetite and ferrihydrite, two important iron oxide phases in nature and in technology. Discrete molecular forms of the iron Keggin ion that can be both manipulated in water and chemically converted to the related metal oxides are important for understanding growth mechanisms, in particular, nonclassical nucleation in which cluster building units are preserved in the aggregation and condensation processes. Here we describe two iron Keggin ion structures, formulated as [BiFeOFeO(OH)(CFCOO)(HO)] (Kegg-1) and [BiFeOFeO(OH)(CFCOO)] (Kegg-2).

Synthesis and crystal structure of [2,7,12-trimethyl-3,7,11,17-tetra-aza-bicyclo-[11.3.1]hepta-deca-1(17),13,15-triene-κ(4) N]copper(II) bis-(perchlorate).

The title copper(II) complex of a pyridine-containing macrocycle (PyMAC), [Cu(C16H28N4)](ClO4)2, has been prepared. The crystal structure reveals the Cu(II) atom to be octahedrally coordinated by a tetradentate aminopyridine macrocyclic ligand surrounding the metal cation in a square-planar geometry. Two weakly bound perchlorate counter-ions occupy the axial sites above and below the macrocyclic plane.

Electronic Spectra of the Tetraphenylcyclobutadienecyclopentadienylnickel(II) Cation and Radical.

Properties of the tetraphenylcyclobutadienecyclopentadienylnickel(II) cation 1 and its tetra-o-fluoro derivative 1a have been measured and calculated. The B3LYP/TZP optimized geometry of the free cation 1 agrees with a single-crystal X-ray diffraction structure except that in the crystal one of the phenyl substituents is strongly twisted to permit a close-packing interaction of two of its hydrogens with a nearby BF4(-) anion. The low-energy parts of the solution electronic absorption and magnetic circular dichroism (MCD) spectra of 1 and 1a have been interpreted by comparison with TD-DFT (B3LYP/TZP) results.

Crystal structure of 4-methyl-N-{(E)-meth-yl[(3aR,8aS)-2-oxo-3,3a,8,8a-tetra-hydro-2H-indeno-[1,2-d][1,3]oxazol-3-yl]-λ(4)-sulfanyl-idene}benzene-sulfonamide.

The formulation that the title compound, C18H18N2O4S2, adopts is a zwitterionic core with the charge separated to the sulfilimine S and N atoms and is supported by the two different S-N bond distances about the sulfinimine N atom [1.594 (2) and 1.631 (2) Å, respectively] that are typical for such bonds.

Bis(cyano) Iron(III) Porphyrinates: What Is the Ground State?

The synthesis of six new bis(cyano) iron(III) porphyrinate derivatives is reported. The anionic porphyrin complexes utilized tetraphenylporphyrin, tetramesitylporphyrin, and tetratolylporphyrin as the porphyrin ligand. The potassium salts of Kryptofix-222 and 18-C-6 were used as the cations.

A supramolecular approach for designing emissive solid-state carbazole arrays.

Reactions of 5-(9H-carbazol-9-yl)-isophthalate and metal salts provide laminar metal organic frameworks (MOFs) wherein interlayer interactions of the pendant carbazoles engender extended aromatic stacks or non-stacked structures with enhanced solid-state emission. These studies emphasize that MOFs serve as versatile supramolecular platforms to direct the aggregation and electroptical behaviours of organic chromophores.

Density functional theory analysis of the impact of steric interaction on the function of switchable polarity solvents.

A density functional theory (DFT) analysis has been performed to explore the impact of steric interactions on the function of switchable polarity solvents (SPS) and their implications on a quantitative structure-activity relationship (QSAR) model previously proposed for SPS. An X-ray crystal structure of the N,N-dimethylcyclohexylammonium bicarbonate (Hdmcha) salt has been solved as an asymmetric unit containing two cation/anion pairs, with a hydrogen bonding interaction observed between the bicarbonate anions, as well as between the cation and anion in each pair. DFT calculations provide an optimized structure of Hdmcha that closely resembles experimental data and reproduces the cation/anion interaction with the inclusion of a dielectric field.

Au133(SPh-tBu)52 nanomolecules: X-ray crystallography, optical, electrochemical, and theoretical analysis.

Crystal structure determination has revolutionized modern science in biology, chemistry, and physics. However, the difficulty in obtaining periodic crystal lattices which are needed for X-ray crystal analysis has hindered the determination of atomic structure in nanomaterials, known as the "nanostructure problem". Here, by using rigid and bulky ligands, we have overcome this limitation and successfully solved the X-ray crystallographic structure of the largest reported thiolated gold nanomolecule, Au133S52.

Enantiomers of a selective gelatinase inhibitor: (R)- and (S)-2-[(4-phenoxyphenyl)sulfonylmethyl]thiirane.

The compound 2-[(4-phenoxyphenyl)sulfonylmethyl]thiirane, C15H14O3S2, a selective gelatinase inhibitor, was synthesized and structurally characterized. Two crystals were analyzed, one each for the R and S enantiomers, and the results were compared with the previously reported structure of the racemate. The enantiomerically pure compounds both crystallize with Z' = 2 in the space group P2₁, while the racemic mixture crystallizes with Z' = 1 in the space group P2₁/c, with disorder in the position of the thiirane group.

A tetrameric cage with D2h symmetry through alkyne metathesis.

Shape-persistent covalent organic polyhedrons (COPs) with ethynylene linkers are usually prepared through kinetically controlled cross-coupling reactions. The high-yielding synthesis of ethynylene-linked rigid tetrameric cages via one-step alkyne metathesis from readily accessible triyne precursors is presented. The tetrameric cage contains two macrocyclic panels and exhibits D2h symmetry.

Santal monohydrate, an isoflavone isolated from Wye-thia mollis.

THE TITLE COMPOUND [SYSTEMATIC NAME: 3-(3,4-di-hydroxy-phen-yl)-5-hy-droxy-7-meth-oxy-4H-chromen-4-one monohydrate], C16H12O6·H2O, is a monohydrate of a natural product santal isolated from Wye-thia mollis. In the santal mol-ecule, the dihedral angle between the benzo-quinone and di-hydroxy-phenyl fragments is 53.9 (1)° and an intra-molecular O-H⋯O hydrogen bond occurs.

(2R,2'S)-2,2'-Bi-piperidine-1,1'-diium dibromide.

The title compound, C10H22N2 (2+)·2Br(-), was synthesized via reduction of 2,2'-dipyridyl with Ni-Al alloy/KOH, followed by separation of diastereoisomers (meso and rac) by recrystallization from ethanol. Although the two bridging C atoms are optically active, these two chiral centers adopt an (S,R) configuration; thus, the title compound contains an achiral meso form of 2,2'-bi-piperidine. Both of the piperidinium rings adopt chair conformations, and the two N atoms are trans to each other; an inversion center is located in the mid-point of the central C-C bond.

Use of silver carbonate in the Wittig reaction.

An efficient synthesis of olefins by the coupling of stabilized, semistabilized, and nonstabilized phosphorus ylides with various carbonyl compounds in the presence of silver carbonate is reported. Wittig olefination of aromatic, heteroaromatic, and aliphatic aldehydes (yields >63%) and a ketone (yield 42%) are demonstrated. These reactions proceed overnight at room temperature, under weakly basic conditions, and as such extend the applicability of the Wittig reaction to base-sensitive reactants.

Tenulin 0.25-hydrate, a sesquiterpene lactone isolated from Helenium amarum.

The asymmetric unit of the title compound, C17H22O5·0.25H2O [systematic name: 2-hy-droxy-2,2a,6,9a-tetra-methyl-2a,4a,5,6,6a,9a,9b,9c-octa-hydro-2H-1,4-dioxadi-cyclo-pent[cd,f]azulene-3,9-dione 0.25-hydrate], a natural product isolated from Helenium amarum, contains two independent tenulin mol-ecules and half a water mol-ecule of crystallization situated on a twofold rotation axis.