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The synthesis and structural characterization of an electron poor Au(III) trication bearing 2 imidazole and 2 acetonitrile ligands is described. The new complex is capable of aryl C–H metalation with the formation of a monomesitylene complex and also demonstrated to be highly oxidizing in the rapid room temperature conversion of cyclohexene to benzene. [ABSTRACT FROM AUTHOR]

A series of nine luminescent iridium(III) complexes with pH-responsive imidazole and benzimidazole ligands have been prepared and characterized. The first series of complexes were of the form [Ir(ppy)2(N^N)]+ or [Ir(ppy)2(C^N)]+ (where ppy is 2-phenylpyridine and N^N is 2-(2-pyridyl)imidazole or 2-(2-pyridyl)benzimidazole and C^N represents a pyridyl-triazolylidene-based N-heterocyclic carbene ligand). For these complexes, the benzimidazole group was either unsubstituted or substituted with electron-withdrawing (Cl) or electron-donating (Me) groups. The second series of complexes were of the form [Ir(phbim)2(N^N)]+ or [Ir(phbim)2(C^N)]+ (where phbim is 2-phenylbenzimidazole and N^N is either 2,2′-bipyridine or 1,10-phenanthroline and C^N is either a pyridyl-imidazolylidene or pyridyl-triazolylidene N-heterocyclic carbene ligand). UV-visible and photoluminescence pH titration studies showed that changing the protonation state of these complexes results in significant changes in the photoluminescence emission properties. The pKa values of prepared complexes were estimated from the spectroscopic pH titration data and these values show that the nature of the pH-sensitive ligands (either main or ancillary ligands) resulted in a significant capacity to modulate the pKa values for these compounds with values ranging from 5.19–11.22. Theoretical investigations into the nature of the electronic transitions for the different protonation states of compounds were performed and the results were consistent with the experimental results. [ABSTRACT FROM AUTHOR]

The recently discovered I(III) reagent NO2-C6H4-I(OTf)2 is found to rapidly react with hydride sources, including HSiEt3 and relatively hydridic C–H precursors. These represent the first distinct reactions involving direct hydride abstraction by I(III) under ambient conditions. Direct C–F abstraction is also demonstrated, as well as oxidation of cyclic alkenes to aromatic rings, all representing new reactions for I(III) demonstrating the very high reactivity of NO2-C6H4-I(OTf)2. [ABSTRACT FROM AUTHOR]

Synthesis and crystallographic characterization of NO2–C6H4–I(NTf2)2 (NTf2 = bistriflimide) is reported. Experimental results find that this compound can perform oxidation reactions that ArI(OTf)2 is unable to and theoretical analysis indicates Ar–I(NTf2)2 is the most oxidizing in the ArIL2 class of compounds known and may also be the most oxidizing compound in the class practically possible. [ABSTRACT FROM AUTHOR]

The structure of Stang's reagent [PhI(CN)][OTf] is confirmed by X-ray crystallography and is determined to be best described as an ion-pair in organic solution. It is found to be a strong Lewis acid, but reaction with pyridine ligands gives [Pyr-CN][OTf] salts via oxidation of pyridine giving a new derivative of the CDAP reagent widely used as an activation agent for polysaccharides. [ABSTRACT FROM AUTHOR]

Both mixed λ3-iodoarenes and λ3-iodoarenes possessing –OTf ligands are coveted for their enhanced reactivities. Here we describe the synthesis, reactivity, and comprehensive characterisation of two new ArI(OTf)(X) species, a class of compound that were previously only invoked as reactive intermediates where X = Cl, F and their divergent reactivity with aryl substrates. A new catalytic system for electrophilic chlorination of deactivated arenes using Cl2 as the chlorine source and ArI/HOTf as the catalyst is also described. [ABSTRACT FROM AUTHOR]

The combination of 4-hydroxybenzoic acid (H2hba) with Li+, Mg2+ and Cu2+ yields coordination polymers in which metal centres are bridged by an anion of the acid, either Hhba− or hba2−. In the case of Li+, a 3D network of composition Li2(hba)DMF was isolated in which parallel channels are occupied by coordinated DMF molecules. Mg2+ combines with H2hba to form a 2D square grid network with the formula Mg(Hhba)2(H2O)2. The alignment of parallel sheets results in the formation of channels filled with 1,4-dioxane molecules that hydrogen bond to coordinated water molecules. The compound Cu3(hba)2(OH)2(1,4-dioxane)1.5·0.5(1,4-dioxane) is a complex 3D network formed from the combination of Cu2+ with H2hba under basic conditions. The crystal structure determination reveals bridging 1,4-dioxane molecules. A reversible phase change occurs in the temperature range 200–220 K. The investigation highlights the key role of the solvent molecules in the structures of this series of compounds. [ABSTRACT FROM AUTHOR]

As part of an educational exercise designed to introduce school students to the technique of single‐crystal X‐ray diffraction and enhance their understanding of primary and secondary bonding, a group of nine secondary school students was given the opportunity to prepare new compounds and to solve and refine data collected on the crystalline materials they had prepared. Their investigation of the alkali metal salts of 4‐hydroxybenzoic acid (H2hba) yielded nine new compounds and their structures are described in this article. Whilst the salts might be expected to have similar atomic arrangements, there are significant differences in their structures. Although H2hba is a relatively simple organic molecule, it displays remarkable coordinative flexibility, forming ionic solids containing the uncharged molecule, the monoanion Hhba− or the dianion hba2−. A common feature of the structures is their layered arrangement: alternating hydrophilic layers made up of closely packed metal–oxygen polyhedra separated by the hydrophobic component of the hydroxybenzoate linking units. Close packing of these units seems to be a dominant influence in determining the overall structure. The hydroxybenzoate units are usually both parallel and antiparallel with their immediate neighbours, with packing that can be edge‐to‐face, face‐to‐face or a mixture of the two. Hydrogen bonding plays a key role in the structure of most compounds and a short strong hydrogen bond (SSHB) is observed in two of the networks. The compounds of 4‐hydroxybenzoic acid, C7H6O3, described here are: poly[di‐μ‐aqua‐μ‐4‐oxidobenzoato‐dilithium], [Li2(C7H4O3)(H2O)2]n, 1, poly[triaqua‐μ‐4‐oxidobenzoato‐dilithium], [Li2(C7H4O3)(H2O)3]n, 2, poly[μ‐4‐hydroxybenzoato‐lithium], [Li(C7H5O3)]n, 3, catena‐poly[4‐hydroxybenzoate [[diaquasodium]‐di‐μ‐aqua]], {[Na(H2O)4](C7H5O3)}n, 4, poly[di‐μ‐aqua‐aqua‐μ‐4‐hydroxybenzoato‐potassium], [K(C7H5O3)(H2O)3]n, 5, poly[μ‐aqua‐μ‐4‐hydroxybenzoato‐potassium], [K(C7H5O3)(H2O)]n, 6, poly[aqua‐μ‐4‐hydroxybenzoato‐rubidium], [Rb(C7H5O3)(H2O)]n, 7, poly[aqua‐μ‐4‐hydroxybenzoato‐caesium], [Cs(C7H5O3)(H2O)]n, 8, poly[[μ‐aqua‐aqua(μ‐4‐hydroxybenzoato)(4‐hydroxybenzoic acid)sodium] monohydrate], {[Na(C7H5O3)(C7H6O3)(H2O)2]·H2O}n, 9, poly[[(μ‐4‐hydroxybenzoato)(μ‐4‐hydroxybenzoic acid)rubidium] monohydrate], {[K(C7H5O3)(C7H6O3)]·H2O}n, 10, and poly[[(μ‐4‐hydroxybenzoato)(μ‐4‐hydroxybenzoic acid)rubidium] monohydrate], {[Rb(C7H5O3)(C7H6O3)]·H2O}n, 11. [ABSTRACT FROM AUTHOR]

A chiral, octahedral M12L12 cage, which is charge neutral and contains an internal void of about 2000 Å3, is reported. The cage was synthesised as an enantiopure complex by virtue of amino‐acid‐based dicarboxylate ligands, which assemble around copper paddlewheels at the vertices of the octahedron. The cage persists in solution with retention of the fluorescence properties of the parent acid. The solid‐state structure contains large pores both within and between the cages, and displays permanent porosity for the sorption of gases with retention of crystallinity. Initial tests show some enantioselectivity of the cage towards guests in solution. [ABSTRACT FROM AUTHOR]

Reaction of the chloranilate dianion with Y(NO3)3 in the presence of Et4N+ in the appropriate proportions results in the formation of (Et4N)[Y(can)2], which consists of anionic square‐grid coordination polymer sheets with interleaved layers of counter‐cations. These counter‐cations, which serve as squat pillars between [Y(can)2] sheets, lead to alignment of the square grid sheets and the subsequent generation of square channels running perpendicular to the sheets. The crystals are found to be porous and retain crystallinity following cycles of adsorption and desorption. This compound exhibits a high affinity for volatile guest molecules, which could be identified within the framework by crystallographic methods. In situ neutron powder diffraction indicates a size‐shape complementarity leading to a strong interaction between host and guest for CO2 and CH4. Single‐crystal X‐ray diffraction experiments indicate significant interactions between the host framework and discrete I2 or Br2 molecules. A series of isostructural compounds (cat)[MIII(X‐an)2] with M=Sc, Gd, Tb, Dy, Ho, Er, Yb, Lu, Bi or In, cat=Et4N, Me4N and X‐an=chloranilate, bromanilate or cyanochloranilate bridging ligands have been generated. The magnetic properties of representative examples (Et4N)[Gd(can)2] and (Et4N)[Dy(can)2] are reported with normal DC susceptibility but unusual AC susceptibility data noted for (Et4N)[Gd(can)2]. An extensive family of square grid anionic coordination polymers is formed by the combination of 8‐coordinate trivalent metal ions with bridging chloranilate ligands. Alignment of the square grid networks produces channels that are able to accommodate a variety species. The location of guest molecules within the channels has been determined using both X‐ray and neutron diffraction. [ABSTRACT FROM AUTHOR]

The need for effective CO2 capture systems remains high, and due to their tunability, metallosupramolecular architectures are an attractive option for gas sorption. While the use of extended metal organic frameworks for gas adsorption has been extensively explored, the exploitation of discrete metallocage architectures to bind gases remains in its infancy. Herein the solid state gas adsorption properties of a series of [Pd2( L)4]4+ lantern shaped coordination cages ( L = variants of 2,6-bis(pyridin-3-ylethynyl)pyridine), which had solvent accessible internal cavities suitable for gas binding, have been investigated. The cages showed little interaction with dinitrogen gas but were able to take up CO2. The best performing cage reversibly sorbed 1.4 mol CO2 per mol cage at 298 K, and 2.3 mol CO2 per mol cage at 258 K (1 bar). The enthalpy of binding was calculated to be 25-35 kJ mol−1, across the number of equivalents bound, while DFT calculations on the CO2 binding in the cage gave Δ E for the cage-CO2 interaction of 23-28 kJ mol−1, across the same range. DFT modelling suggested that the binding mode is a hydrogen bond between the carbonyl oxygen of CO2 and the internally directed hydrogen atoms of the cage. [ABSTRACT FROM AUTHOR]

A ZnII complex of the dianionic tetradentate ligand formed by deprotonation of glyoxal-bis(4-phenyl-3-thiosemicarbazone) (H2gtsp) is a [3+3] trinuclear triangular prism. Recrystallization of this complex in the presence of either CO2, CS2, or CH3CN leads to the formation of [4+4] open-ended charge-neutral tetranuclear coordination nanotubes, approximately 2 nm in length and with internal dimensions large enough to accommodate linear guest molecules, which serve to template their formation. Upon removal of the templating molecules the nanotubes demonstrated reversible sorption of CO2 with an isosteric enthalpy of sorption of 28 kJ mol−1 at low loading. [ABSTRACT FROM AUTHOR]

A ZnII complex of the dianionic tetradentate ligand formed by deprotonation of glyoxal-bis(4-phenyl-3-thiosemicarbazone) (H2gtsp) is a [3+3] trinuclear triangular prism. Recrystallization of this complex in the presence of either CO2, CS2, or CH3CN leads to the formation of [4+4] open-ended charge-neutral tetranuclear coordination nanotubes, approximately 2 nm in length and with internal dimensions large enough to accommodate linear guest molecules, which serve to template their formation. Upon removal of the templating molecules the nanotubes demonstrated reversible sorption of CO2 with an isosteric enthalpy of sorption of 28 kJ mol−1 at low loading. [ABSTRACT FROM AUTHOR]

The uptake of inhalation anesthetics by three topologically identical frameworks is described. The 3D network materials, which possess square channels of different dimensions, are formed from the relatively simple combination of ZnII centres and dianionic ligands that contain a phenolate and a carboxylate group at opposite ends. All three framework materials are able to adsorb N2O, Xe and isoflurane. Whereas the framework with the widest channels is able to adsorb large quantities of the various guests from the gas phase, the frameworks with the narrower channels have superior binding enthalpies and exhibit higher levels of retention. The use of ligands in which substituents are bound to the aromatic rings of the bridging ligands offers great scope for tuning the adsorption properties of the framework materials. [ABSTRACT FROM AUTHOR]

The combination of lightweight metal cations with a range of dicarboxylate ligands has led to the generation of ionic network materials that possess channels occupied by solvent molecules. The compounds [Li2(2,2-bpdc)(DMF)2] and [Mg(2,2-bpdc)(DMF)2] (2,2-bpdc=2,2-dipyridyl-4,4-dicarboxylate) adopt a similar structure in which parallel metal-carboxylate chains are linked to four equivalent chains to generate a 3 D network in which DMF molecules occupy channels. [Li4(3,5-pdc)2(DMF)]⋅solvate (3,5-pdc=3,5-pyridine dicarboxylate) adopts a similar structure but the chains are more complex. As with the other structures, coordinated DMF molecules occupy network channels. [Li4(3,5-pdc)2(DMF)]⋅solvate is able to adsorb carbon dioxide at elevated pressures with the adsorption following a type V isotherm; hysteresis is apparent upon desorption. The final compound, Li[Mg3OH(2,2-bqdc)3(DMF/H2O)3]⋅solvate (2,2-bqdc=2,2-biquinoline-4,4-dicarboxylate) has a distinctly different structure in which a trio of magnesium centres bound to a central μ3-hydroxide ion serves as a 6-connecting, trigonal prismatic node within a 3 D network that has the point symbol, 4966. Solvent-filled intraframework spaces represent over 50 % of the crystal volume and are occupied by highly disordered solvent and Li+ ions. Immersion of Li[Mg3OH(2,2-bqdc)3(DMF/H2O)3]⋅solvate in a solution of Fe(2,2-bipyridine)32+ results in the incorporation of the FeII complex into the large channels of the anionic network. [ABSTRACT FROM AUTHOR]

A series of solid-state structural transformations are found to accompany desolvation of relatively simple coordination polymers to yield materials that exhibit unexpected gas sorbing properties. Reaction of 1,2,4,5-tetrahydroxybenzene with MII salts (M = Mg, or Zn) in an alcohol/water solution in the presence of air affords cis-MII(C6H2O4−II)(H2O)2·2H2O·xROH, (M = Mg, or Zn), crankshaft-like chains in which the absolute configurations of the chiral metal centres follow the pattern …ΔΔΛΛΔΔΛΛ…, and are hydrogen bonded together to generate spacious channels. When crystals of the crankshaft chain are air dried the crystals undergo a single crystal-to-powder rearrangement to form linear trans-MII(C6H2O4−II)(H2O)2 chains. Further dehydration yields microporous solids that reversibly sorb H2, CH4 and CO2 with high sorption enthalpies. [ABSTRACT FROM AUTHOR]

The structure of Li(inox) ⋅2/3 DMF (inox−=the N-oxide of the isonicotinate anion) consists of a 3D framework with solvent-filled, square cross-section channels of approximate dimensions 5.5×5.5 Å. Unfortunately, the Li(inox) framework is unstable upon removal of DMF from the channels. When the structurally related 4-hydroxybenzoic acid (H2hba) was used in place of Hinox, and Zn2+ in place of the Li+, a structurally similar but more robust network, Zn(hba), was obtained; the isostructural compound, Co(hba), may also be prepared. Longer ligands with phenolate and carboxylate functional groups at opposite ends, such as the dianions of 4-coumaric acid (H2cma) and 4′-hydroxy-4-biphenylcarboxylic acid (H2hbpc), in combination with Zn2+ yield Zn(cma) and Zn(hbpc) frameworks, respectively, with the same PtS topology but with larger channels. The coordination polymers remain intact after desolvation and exhibit microporosity, showing the ability to sorb significant quantities of CO2, CH4, and H2. [ABSTRACT FROM AUTHOR]

A new piperazine-derived ligand has been prepared and used to synthesise a porous coordination polymer which displays selective carbon dioxide uptake after solvent exchange and thermal activation. The ligand N,N′-bis(4-carboxyphenylmethylene)piperazine H2L1 was prepared from piperazine in three steps and good yield. A structure containing the deprotonated form K2L1·2H2O was determined and consists of a three-dimensional coordination polymer containing inorganic K2(COO)2(OH2) layers separated by the long organic bridging linker. The free compound H2L1 displays a one-dimensional hydrogen-bonded polymeric structure in the solid state with hydrogen bonding interactions between carboxylic acids and piperazine groups tightly linking molecules together. The two-dimensional polymeric complex [Zn3(L1)2(OH)2]·2DMF·0.5H2O 1 was prepared and analysed in the solid state to reveal tubular one-dimensional channels which, when activated by solvent exchange and evacuation, displayed selective affinity for CO2 over N2 and H2. [ABSTRACT FROM AUTHOR]

The monoanion of 1,3-bis(carboxymethyl)imidazolium (H2imdc+) combines with Cu(ii) to produce an undulating 2D coordination polymer of composition [Cu2(imdc)2(CH3OH)2](BF4)2·(CH3OH)(H2O) (1) in which copper acetate-like dimers, linked by imdc− ligands, act as 4-connecting centres. Cationic sheets stack on top of each other in an A, B, A, B… fashion and produce a structure that contains channels running parallel to the plane of network. Tetrafluoroborate anions are located in channels between sheets. Upon removal of coordinated and non-coordinated solvent molecules a single crystal-to-single crystal transformation occurs to yield a similar compound but with BF4− anions now coordinated. CO2 isotherms measured at 258 and 273 K show only modest uptake of CO2 but provide an indication that the sheets move apart at elevated pressures in order to accommodate the guest molecules. A compound of composition [Cu3(OH)2(imdc)2]·SiF6·2H2O·2MeOH (3), which possesses a 3D network, is formed by the combination of copper(ii) acetate, copper(ii) hexafluorosilicate and Himdc. In this structure infinite parallel Cu3(OH)2 chains are linked by bridging imdc− ligands to form channels that have an approximately triangular cross-section. These channels are occupied by SiF62− anions in addition to solvent molecules. When copper(ii) acetate is combined with Himdc in the appropriate ratio, a 1D coordination polymer of composition Cu(imdc)2 (4) is formed in which pairs of imdc− anions bridge Cu(ii) centres. When the reaction is performed in the presence of NaBF4 a minor crystalline product with tetragonal symmetry is isolated in addition to the 1D coordination polymer. This compound of composition Cu2(imdc)4NaBF4·7H2O (5) consists of 2D Cu(imdc)2 networks and features an unusual mode of interpenetration. [ABSTRACT FROM AUTHOR]

Analysis of in situ neutron powder diffraction data collected for the porous framework material Zn(hba) during gas adsorption reveals a two-stage response of the host lattice to increasing CO2 guest concentration, suggesting progressive occupation of multiple CO2 adsorption sites with different binding strengths. The response of the lattice to moderate CH4 guest concentrations is virtually indistinguishable from the response to CO2, demonstrating that the influence of host–guest interactions on the Zn(hba) framework is defined more strongly by the concentration than by the identity of the guests. [ABSTRACT FROM AUTHOR]

Caging carbon dioxide: Self ‐ assembled discrete palladium(II) [Pd2(L)4]4+ cages with 2,6 ‐ bis(pyridin ‐ 3 ‐ ylethynyl)pyridine) ligands (L) have cavities, which bind guests containing carbonyl groups through hydrogen bonding interactions. In the solid state these cages have now been shown to bind up to four CO2 molecules, with selectivity over N2. Long ‐ range order in the packing of the molecules in powdered samples of the compound does not appear to be necessary for their activity, making their preparation easy. Additionally, the cages can be readily functionalized, opening up avenues for selective guest binding and gas separations. More information can be found in the Full Paper by B. F. Abrahams, J. D. Crowley et al. on page 10559. [ABSTRACT FROM AUTHOR]

Reversible Sorption of CO2Templating molecules in square coordination nanotubes of dianionic bridging ligands and zinc(II) centers can be replaced by CO2 molecules as described by B. M. Paterson, B. F. Abrahams, P. S. Donnelly et al. in their Communication on page 8370 ff. [ABSTRACT FROM AUTHOR]

Reversible CO2‐SorptionDie Templatmoleküle in quadratischen Koordinationsnanoröhren aus dianionischen Brückenliganden und Zink(II)‐Zentren können durch CO2‐Moleküle ersetzt werden, wie B. M. Paterson, B. F. Abrahams, P. S. Donnelly et al. in der Zuschrift auf S. 8490 ff. beschreiben. [ABSTRACT FROM AUTHOR]