Transitioning from Methanol to Olefins (MTO) toward a Tandem CO Hydrogenation Process: On the Role and Fate of Heteroatoms (Mg, Si) in MAPO-18 Zeotypes.

The tandem CO hydrogenation to hydrocarbons over mixed metal oxide/zeolite catalysts (OXZEO) is an efficient way of producing value-added hydrocarbons (platform chemicals and fuels) directly from CO methanol intermediate in a single reactor. In this contribution, two MAPO-18 zeotypes (M = Mg, Si) were tested and their performance was compared under methanol-to-olefins (MTO) conditions (350 °C, = 0.04 bar, 6.

A Survey of the Angular Distortion Landscape in the Coordination Geometries of High-Spin Iron(II) 2,6-Bis(pyrazolyl)pyridine Complexes.

Reaction of 2,4,6-trifluoropyridine with sodium 3,4-dimethoxybenzenethiolate and 2 equiv of sodium pyrazolate in tetrahydrofuran at room temperature affords 4-(3,4-dimethoxyphenylsulfanyl)-2,6-di(pyrazol-1-yl)pyridine (), in 30% yield. The iron(II) complexes [Fe][BF] () and [Fe][ClO] () are high-spin with a highly distorted six-coordinate geometry. This structural deviation from ideal symmetry is common in high-spin [Fe(bpp)] (bpp = di{pyrazol-1-yl}pyridine) derivatives, which are important in spin-crossover materials research.

Cation-induced speciation of port-size during mordenite zeolite synthesis.

Mordenite (MOR) zeolite, an important industrial catalyst exists in two, isostructural variants defined by their port-size, small and large-port. Here we show for the first time how a systematic, single-parameter variation influences the synthesis out-come on the final MOR material leading to distinctly different catalysts. The cation identity has a direct impact on the synthesis mechanism with potassium cations generating the more constrained, small-port MOR variant compared to the large-port obtained with sodium cations.

Li(CHN)FeSe: A Defect-Resilient Expanded-Lattice High-Temperature Superconductor.

Two-dimensional iron chalcogenide intercalates display a remarkable correlation of the interlayer spacing with enhancement of the superconducting critical temperature (). In this work, synchrotron X-ray absorption (XAS; at the Fe and Se K-edges) and emission (XES; at the Fe Κβ) spectroscopies allow one to discuss how the important rise of (∼44 K) in the molecule-intercalated Li(CHN)FeSe relates to the electronic and local structural changes felt by the inorganic host upon doping (). XES shows that widely separated layers of edge-sharing FeSe tetrahedra carry low-spin moieties, with a local Fe magnetic moment slightly reduced compared to the parent β-FeSe.

Structures and Spin States of Iron(II) Complexes of Isomeric 2,6-Di(1,2,3-triazolyl)pyridine Ligands.

Iron(II) complex salts of 2,6-di(1,2,3-triazol-1-yl)pyridine (L) are unexpectedly unstable in undried solvent. This is explained by the isolation of [Fe(L)(HO)][ClO] and [Fe(NCS)(L)(HO)]·L, containing L bound as a monodentate ligand rather than in the expected tridentate fashion. These complexes associate into 4 grid structures through O-H···N hydrogen bonding; a solvate of a related 4 coordination framework, -[Cu(μ-L)(HO)][BF], is also presented.

The number and shape of lattice solvent molecules controls spin-crossover in an isomorphous series of crystalline solvate salts.

Crystals of [FeL2][BF4]2·nMeCN (L = N-(2,6-di{pyrazol-1-yl}pyrid-4-yl)acetamide; n = 1 or 2) and [FeL2][ClO4]2·MeCN are isomorphous. When n = 1 the compounds exhibit an abrupt, hysteretic spin-transition below 200 K, but when n = 2 the material remains high-spin on cooling. [FeL2]X2·EtCN (X- = BF4- or ClO4-) are isomorphous with the MeCN solvates and undergo their spin-transition at almost the same temperature.

The effect of tether groups on the spin states of iron(II)/bis[2,6-di(pyrazol-1-yl)pyridine] complexes.

The synthesis of six 2,6-di(pyrazol-1-yl)pyridine derivatives bearing dithiolane or carboxylic acid tether groups is described: [2,6-di(pyrazol-1-yl)pyrid-4-yl]methyl (R)-lipoate (L1), 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxamido]ethyl (R)-lipoate (L2), 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxy]ethyl (R)-lipoate (L3), N-([2,6-di(pyrazol-1-yl)pyrid-4-ylsulfanyl]-2-aminoethyl (R)-lipoamide (L4), 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxamido]acetic acid (L5) and 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxamido]propionic acid (L6). The iron(ii) perchlorate complexes of all the new ligands exhibit gradual thermal spin-crossover (SCO) in the solid state above room temperature, except L4 whose complex remains predominantly high-spin. Crystalline [Fe(L6)2][ClO4]2·2MeCN contains three unique cation sites which alternate within hydrogen-bonded chains, and undergo gradual SCO at different temperatures upon warming.

Molecular squares, coordination polymers and mononuclear complexes supported by 2,4-dipyrazolyl-6H-1,3,5-triazine and 4,6-dipyrazolylpyrimidine ligands.

The Fe[BF4]2 complex of 2,4-di(pyrazol-1-yl)-6H-1,3,5-triazine (L1) is a high-spin molecular square, [{Fe(L1)}4(μ-L1)4][BF4]8, whose crystals also contain the unusual HPzBF3 (HPz = pyrazole) adduct. Three other 2,4-di(pyrazol-1-yl)-6H-1,3,5-triazine derivatives with different pyrazole substituents (L2-L4) are unstable in the presence of first row transition ions, but form mononuclear, polymeric or molecular square complexes with silver(i). Most of these compounds involve bis-bidentate di(pyrazolyl)triazine coordination, which is unusual for that class of ligand, and the molecular squares encapsulate one or two BF4-, ClO4- or SbF6- ions through combinations of anionπ, AgX and/or C-HX (X = O or F) interactions.

Supramolecular Iron Metallocubanes Exhibiting Site-Selective Thermal and Light-Induced Spin-Crossover.

Treatment of Fe[BF]·6HO with 4,6-di(pyrazol-1-yl)-1-pyrimid-2-one (HL) or 4,6-di(4-methylpyrazol-1-yl)-1-pyrimid-2-one (HL) affords solvated crystals of [{Fe(OH)}⊂Fe(μ-L)][BF] (, HL = HL; , HL = HL). The centrosymmetric complexes contain a cubic arrangement of iron(II) centers, with bis-bidentate [L] ligands bridging the edges of the cube. The encapsulated [Fe(OH)] moiety templates the assembly through 12 O-H···O hydrogen bonds to the [L] hydroxylate groups.

Heterometallic Coordination Polymer Gels Supported by 2,4,6-Tris(pyrazol-1-yl)-1,3,5-triazine.

Complexes of type [M(tpt)]X (M = Fe, Co, Ni; tpt = 2,4,6-tri{pyrazol-1-yl}-1,3,5-triazine; X = BF or ClO ) crystallize in a cubic lattice, with the metal ion and ligand conformation showing unusual symmetry-imposed disorder. Addition of 1 equiv AgX to the corresponding preformed [M(tpt)]X salt in concentrated MeNO solution affords thixotropic gels. Gelation was not observed in analogous reactions using [Mn(tpt)][ClO], or from reactions in other, more donating solvents.

Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials.

Structure-function relationships relating the spin-crossover (SCO) midpoint temperature () in the solid state are surveyed for 43 members of the iron(II) dipyrazolylpyridine family of SCO compounds. The difference between in the solid state and in solution [Δ(latt)] is proposed as a measure of the lattice contribution to the transition temperature. Negative linear correlations between the SCO temperature and the magnitude of the rearrangement of the coordination sphere during SCO are evident among isostructural or near-isostructural subsets of compounds; that is, a larger change in the molecular structure during SCO stabilizes the high-spin state of a material.

Silver(i) complexes of bis- and tris-(pyrazolyl)azine derivatives - dimers, coordination polymers and a pentametallic assembly.

Silver(i) complexes of 2,4,6-tri(pyrazol-1-yl)pyridine (tpp), 2,4,6-tri(pyrazol-1-yl)pyrimidine (tpym), 2,4,6-tri(pyrazol-1-yl)-1,3,5-triazine (tpt) and 2,4-di(pyrazol-1-yl)-1,3,5-triazine (bpt) are reported. Dinuclear [Ag2(μ-tpp)2(MeCN)2][BF4]2·2MeCN and [Ag2(μ-tpym)2(MeCN)2][BF4]2 are formed from approximately planar [AgL(NCMe)]+ (L = tpp or bpym) centres, which dimerise via apical interactions to the pendant pyrazolyl donor on each ligand. Two polymeric solvatomorph phases [Ag2(μ-tpp)2][BF4]2·nMeNO2 were obtained by crystallising AgBF4 and tpp from nitromethane solution.

An Incomplete Spin Transition Associated with a Z'=1→Z'=24 Crystallographic Symmetry Breaking.

Crystalline [FeL ][BF ] ⋅Me CO (L=N-[2,6-di{pyrazol-1-yl}pyrid-4-yl]acetamide) is high-spin at room temperature, and undergoes an abrupt, hysteretic spin-crossover at T1/2 =137 K (ΔT1/2 =14 K) that proceeds to about 50 % completeness. This is associated with a crystallographic phase transition, from phase 1 (P2 /c, Z=4) to phase 2 (P2 , Z=48). The cations associate into chains in the crystal through weak intermolecular π⋅⋅⋅π interactions.

Iron(II) Complexes of 2,4-Dipyrazolyl-1,3,5-triazine Derivatives-The Influence of Ligand Geometry on Metal Ion Spin State.

Seven [FeL][BF] complex salts were prepared, where L is a 6-substituted 2,4-di(pyrazol-1-yl)-1,3,5-triazine (bpt) derivative. The complexes are all crystallographically high-spin, and exhibit significant distortions from an ideal D-symmetric coordination geometry. In one case, an unusual type of metal ion disorder was observed among a cubic array of ligands in the crystal lattice.