Cation‐Controlled Assembly of Polyoxotungstate‐Based Coordination Networks

The Preyssler polyoxoanion, [NaP₅W₃₀O₁₁₀]^14? ({P₅W₃₀}), is used as a platform for evaluating the role of nonbridging cations in the formation of transition‐metal‐bridged polyoxometalate (POM) coordination frameworks. Specifically, the assembly architecture of Co²⁺‐bridged frameworks is shown to be dependent on the identity and amount of alkali or alkaline‐earth cations present during crystallization. The inclusion of Li⁺, Na⁺, K⁺, Mg²⁺, or Ca²⁺ in the framework synthesis is used to selectively synthesize five different Co²⁺‐bridged {P₅W₃₀} structures. The influence of the competition between K⁺ and Co²⁺ for binding to {P₅W₃₀} in dictating framework assembly is evaluated. The role of ion pairing on framework assembly structure and available void volume is discussed. Overall, these results provide insight into factors governing the ability to achieve controlled assembly of POM‐based coordination networks.     

Yolk–shell microspheres assembled from Preyssler‐type NaP5W30O11014− polyoxometalate and MIL‐101(Cr) metal–organic framework: A new inorganic–organic nanohybrid for fast and selective removal of cationic organic dyes from aqueous media

Novel inorganic–organic yolk–shell microspheres based on Preyssler‐type NaP₅W₃₀O₁₁₀^14? polyoxometalate and MIL‐101(Cr) metal–organic framework (P₅W₃₀/MIL‐101(Cr)) were synthesized by reaction of K_12.5Na_1.5[NaP₅W₃₀O₁₁₀], Cr(NO₃)₃·9H₂O and terephthalic acid under hydrothermal conditions at 200°C for 24 h. The as‐prepared yolk–shell microspheres were fully characterized using various techniques. All analyses confirmed the incorporation of the Preyssler‐type NaP₅W₃₀O₁₁₀^14? polyoxometalate into the three‐dimensional porous MIL‐101(Cr) metal–organic framework. The results revealed that P₅W₃₀/MIL‐101(Cr) demonstrated rapid adsorption of cationic methylene blue (MB) and rhodamine B (RhB) with ultrahigh efficiency and capacity, as well as achieving rapid and highly selective adsorption of MB from MB/MO (MO = methyl orange), MB/RhB and MB/RhB/MO mixtures. The P₅W₃₀/MIL‐101(Cr) adsorbent not only exhibited a high adsorption capacity of 212 mg g^?1, but also could quickly remove 100% of MB from a dye solution of 50 mg l^?1 within 8 min. The effects of some key parameters such as adsorbent dosage, initial dye concentration and initial pH on dye adsorption were investigated in detail. The equilibrium adsorption data were better fitted by the Langmuir isotherm. The adsorption kinetics was well modelled using a pseudo‐second‐order model. Also, the inorganic–organic hybrid yolk–shell microspheres could be easily separated from the reaction system and reused up to four times without any change in structure or adsorption ability. The stability and robustness of the adsorbent were confirmed using various techniques.     

Two Organic–Inorganic Hybrid 3D {P5W30}‐Based Heteropolyoxotungstates with Transition‐Metal/Ln–Carboxylate–Ln Connectors

Two unique organic–inorganic hybrid polyoxometalates constructed from Preyssler‐type [Na(H₂O)P₅W₃₀O₁₁₀]^14? ({P₅W₃₀}) subunits and TM/Ln–carboxylate–Ln connectors (TM=transition metal, Ln=lanthanide), KNa₇[{Sm₆Mn(μ‐H₂O)₂(OCH₂COO)₇(H₂O)₁₈}{Na(H₂O)P₅W₃₀O₁₁₀}] ? 22 H₂O ( 1 ) and K₄[{Sm₄Cu₂(gly)₂(ox)(H₂O)₂₄}{NaP₅W₃₀O₁₁₀}]Cl₂ ? 25 H₂O ( 2 ; gly=glycine, ox=oxalate) have been hydrothermally synthesized and characterized by elemental analyses, IR spectra, UV/Vis‐NIR spectra, thermogravimetric analyses, power X‐ray diffraction, and single‐crystal X‐ray diffraction. Compound 1 displays one interesting 3D framework built by three types of subunits, {P₅W₃₀}, [Sm₂Mn(μ‐H₂O)₂(OCH₂COO)₂(H₂O)₅]⁴⁺, and [Sm₄(OCH₂COO)₅ (H₂O)₁₃]²⁺, whereas 2 also manifests the other intriguing 3D architecture created by three types of subunits, {P₅W₃₀}, [SmCu(gly)(H₂O)₈]⁴⁺, and [Sm₂(ox)(H₂O)₈]⁴⁺. To our knowledge, 1 and 2 are the first 3D frameworks that contain {P₅W₃₀} units and TM/Ln–carboxylate–Ln connectors. The fluorescent properties of 1 and 2 have been investigated.     

Cation-Controlled Assembly of Polyoxotungstate-Based Coordination Networks

The Preyssler polyoxoanion, [NaP₅W₃₀O₁₁₀]¹⁴⁻ ({P₅W₃₀}), is used as a platform for evaluating the role of nonbridging cations in the formation of transition-metal-bridged polyoxometalate (POM) coordination frameworks. Specifically, the assembly architecture of Co²⁺-bridged frameworks is shown to be dependent on the identity and amount of alkali or alkaline-earth cations present during crystallization. The inclusion of Li⁺, Na⁺, K⁺, Mg²⁺, or Ca²⁺ in the framework synthesis is used to selectively synthesize five different Co²⁺-bridged {P₅W₃₀} structures. The influence of the competition between K⁺ and Co²⁺ for binding to {P₅W₃₀} in dictating framework assembly is evaluated. The role of ion pairing on framework assembly structure and available void volume is discussed. Overall, these results provide insight into factors governing the ability to achieve controlled assembly of POM-based coordination networks.     

Solid-State Ion Migration in the Preyssler-Type Phosphotungstate for the Preparation of the Dipotassium Cation-Encapsulated Derivative

The heat-driven solid-state transformations of K salts of the Na-encapsulated Preyssler-type phosphotungstates, K₁₄[P₅W₃₀O₁₁₀Na(side)(H₂O)] and K₁₄[P₅W₃₀O₁₁₀Na(center)], are reported herein. K₁₄[P₅W₃₀O₁₁₀Na(side)(H₂O)] contains one Na⁺ in one of the side cavities and a coordinating H₂O molecule while K₁₄[P₅W₃₀O₁₁₀Na(center)] contains one Na⁺ in the central cavity. The heating of K₁₄[P₅W₃₀O₁₁₀Na(side)(H₂O)] produces [P₅W₃₀O₁₁₀Na(center)]^14–, [P₅W₃₀O₁₁₀K(center)]^14–, and [P₅W₃₀O₁₁₀K(side)₂]^13–. [P₅W₃₀O₁₁₀K(center)]^14– and [P₅W₃₀O₁₁₀K(side)₂]^13– contain mono-K⁺ in the central cavity and di-K⁺ in both side cavities, respectively. The heating of potassium salt of [P₅W₃₀O₁₁₀Na(center)]^14– produces [P₅W₃₀O₁₁₀K(center)]^14– and [P₅W₃₀O₁₁₀K(side)₂]^13–. These results indicate that heating, at 200–500 °C, causes the migrations of Na⁺ and K⁺, without the collapse of the molecule. K₁₄[P₅W₃₀O₁₁₀Na(side)(H₂O)] was successfully converted to K₁₂Na[P₅W₃₀O₁₁₀K(side)₂] by repeated solid-state heating, which was periodically interrupted by dissolution, in H₂O, and drying.     

Supported Preyssler Nanoparticles in Synthesis of 1,3‐Diaryl‐5‐Spirohexahydropyrimidines

Silica‐supported Preyssler nanoparticles (H₁₄[NaP₅W₃₀O₁₁₀])/SiO₂ are used as a new and recyclable catalyst for the preparation of 1,3‐diaryl‐5‐spirohexahydropyrimidines via a one‐pot condensation of anilines, formaldehyde, and cyclohexanone.     

syn and anti conformations in 2‐hydroxy‐5‐[(E)‐(4‐nitrophenyl)diazenyl]benzoic acid and two related salts

The crystal structures of 2‐hydroxy‐5‐[(E)‐(4‐nitrophenyl)diazenyl]benzoic acid, C₁₃H₉N₃O₅, (I), ammonium 2‐hydroxy‐5‐[(E)‐phenyldiazenyl]benzoate, NH₄⁺·C₁₃H₉N₂O₃⁻, (II), and sodium 2‐hydroxy‐5‐[(E)‐(4‐nitrophenyl)diazenyl]benzoate trihydrate, Na⁺·C₁₃H₈N₃O₅⁻·3H₂O, (III), have been determined using single‐crystal X‐ray diffraction. In (I) and (III), the phenyldiazenyl and carboxylic acid/carboxylate groups are in an anti orientation with respect to each other, which is in accord with the results of density functional theory (DFT) calculations, whereas in (II), the anion adopts a syn conformation. In (I), molecules form slanted stacks along the [100] direction. In (II), anions form bilayers parallel to (010), the inner part of the bilayers being formed by the benzene rings, with the –OH and –COO⁻ substituents on the bilayer surface. The NH₄⁺ cations in (II) are located between the bilayers and are engaged in numerous N—H...O hydrogen bonds. In (III), anions form layers parallel to (001). Both Na⁺ cations have a distorted octahedral environment, with four octahedra edge‐shared by bridging water O atoms, forming [Na₄(H₂O)₁₂]⁴⁺ units.     

Potentiometric and spectroscopic studies of three new mixed inorganic–organic hybrid materials based on Preyssler and Wells–Dawson heteropolyoxometalates containing proline, leucine, and asparagine

Three new organic–inorganic hybrid materials based on two important heteropolyoxometalates namely Preyssler (=K_12.5H_1.5[Na(H₂O)P₅W₃₀O₁₁₀]·35H₂O) and Wells–Dawson (=K₆[P₂W₁₈O₆₂]·10H₂O) anions, namely, (Hpro)₉(Hleu)₃K₂[Na(H₂O)P₅W₃₀O₁₁₀]·25H₂O (1), (Hpro)₄(Hasp)[HP₂W₁₈O₆₂]·20H₂O (2), and (Hpro)₁₁K₃[Na(H₂O)P₅W₃₀O₁₁₀]·18H₂O (3) where pro, leu, and asp are proline, leucine, and asparagine, respectively, were prepared and identified by elemental analysis, infrared and proton nuclear magnetic resonance spectroscopies, and thermogravimetric analysis. The hybrid materials are made up of positively charged amino acids, [Na(H₂O)P₅W₃₀O₁₁₀]^14? and [P₂W₁₈O₆₂]^6? anions, and H₂O molecules of crystallization. These constituents’ fragments held together into a three-dimensional supermolecular network through non-covalent interactions. The protonation constants of the amino acids used, and Preyssler and Wells–Dawson species in all possible protonated forms, the equilibrium constants for binary systems of proline–asparagine and proline–leucine, and the stoichiometry and stability constants of the corresponding binary and ternary hybrids with Preyssler and Wells–Dawson heteropolyoxometalates in aqueous solution were investigated by potentiometric pH titration method. The stoichiometries of the most hybrid species in solution were compared with the corresponding hybrids in the solid phase, in detail.     

Supramolecular Structures of Titanium(IV)‐Substituted Wells–Dawson Polyoxotungstates

The novel, dimeric titanium(IV )‐substituted phosphotungstate [(TiP₂W₁₅O₅₅OH)₂]^14? ( 1 ) has been synthesized and characterized by IR and ³¹P NMR spectroscopy, elemental analysis, and single‐crystal Xray diffraction. The polyanion consists of two [P₂W₁₅O₅₆]^12? Wells–Dawson moieties linked through two titanium(IV ) centers. Polyanion 1 is a dilacunary species and represents the first Ti‐containing sandwich‐type structure. The titanium centers are octahedrally coordinated by three oxygen atoms of each P₂W₁₅O₅₆ subunit. The edge‐shared TiO₆ units are symmetrically equivalent and have no terminal ligands. Polyanion 1 shows a chiral distortion within each P₂W₁₅Ti fragment. We also report on the structural characterization of the tetrameric, supramolecular species [{Ti₃P₂W₁₅O_57.5(OH)₃}₄]^24? ( 2 ). Polyanion 2 is composed of four equivalent P₂W₁₅Ti₃ fragments, fused together through terminal Ti? O bonds, leading to a structure with T_d symmetry.     

Bi37InBr48: Eine polares Subhalogenid mit Bi95+‐Polykationen,komplexen Bromobismutat(III)‐Anionen [Bi3Br13]4— und [Bi7Br30]9— sowie Pentabromoindat(III)‐Anionen [InBr5]2—

Bi₃₇InBr₄₈: a Polar Subhalide with Bi₉⁵⁺ Polycations, Complex Bromobismuthate(III) Anions [Bi₃Br₁₃]^4— and [Bi₇Br₃₀]^9—, and Pentabromoindate(III) Anions [InBr₅]^2— Black crystals of Bi₃₇InBr₄₈ were synthesized from bismuth, indium and BiBr₃ by cooling stoichiometric melts from 570 K to 470 K. X‐ray diffraction on powders and single‐crystals revealed that the compound crystallizes with space group P 6₃ (a = 2262.6(4); c = 1305.6(2) pm). The Bi₉⁵⁺ polycations in the polar crystal structure have the shape of heavily distorted tri‐capped trigonal prisms with approximate C_s symmetry. The high complexity of the structure results from three coexisting types of anionic groups: Three edge‐sharing [BiBr₆] octahedra constitute the trigonal bromobismuthate(III) anion [Bi₃Br₁₃]^4—. Four [BiBr₆] and three [BiBr₅] polyhedra share common vertices to form the [Bi₇Br₃₀]^9— hemi‐sphere, in which the trigonal bipyramid of the pentabromoindat(III) ion [InBr₅]^2— is embedded.     

A New 2D Fluorescent Polyoxometalate Built up of Circular {P5W30} Clusters and Tb3+ Cations

A new all inorganic polyoxometalate (POM), which is composed of the [Na(H₂O)P₅W₃₀O₁₁₀]^14– ({P₅W₃₀}) clusters and Tb³⁺ cations, Na₂[Tb₄(H₂O)₂₈{Na(H₂O)P₅W₃₀O₁₁₀}] · 16H₂O ( 1 ), was obtained by using hydrothermal method. Its structure was further characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, TG, and PXRD. Compound 1 displays a 2D layered structure formed by {P₅W₃₀} clusters and [Tb(H₂O)₇]³⁺ linkers. It noteworthy that, eight coordinated sites provided by {P₅W₃₀} was very rare. Furthermore, the luminescent property of compound 1 was reported.     

Zwei Tetrachlorothiotantalate: [Na‐15‐Krone‐5][TaSCl4 · Dioxan] und [Na‐15‐Krone‐5]2[(TaSCl4)2Dioxan] · S8

Two Tetrachlorothiotantalates: [Na‐15‐crown‐5][TaSCl₄ · dioxane] and [Na‐15‐crown‐5]₂[(TaSCl₄)₂dioxane] · S₈ During the reaction of Na₂S₄, TaCl₅ and 15‐crown‐5 in dichloromethane the crown ether partly suffers degradation to 1,4‐dioxane. Aside from sulfur, [Na‐15‐crown‐5][TaSCl₄ · dioxane] was the first product obtained. It crystallizes in the monoclinic space group P2₁/n with a = 1066.1, b = 1781.3, c = 1258.3 pm, β = 97.14°, Z = 4. In the [TaSCl₄ · dioxane]^– ion a dioxane molecule is loosely bonded to a square‐pyramidal TaSCl₄^– unit; two chlorine atoms are in contact with an Na⁺ ion. Upon standing with the mother liquor [Na‐15‐crown‐5]₂[(TaSCl₄)₂dioxane] · S₈ was formed. It crystallizes in the monoclinic space group C2/m; a = 1768.5, b = 1084.0, c = 1517.3 pm, β = 118.46°, Z = 4. In this case a dioxane molecule is coordinated with two TaSCl₄^– units. The [(TaSCl₄)₂ · dioxane]^2– ions and S₈ molecules alternate in the stacking direction b.     

Poly[tetrasodium(I)‐tetra‐μ2‐bis(butane‐1,4‐diyldioxy)borato‐μ2‐1,4‐butane­diol]

In the title compound, [Na₄(C₈H₁₆BO₄)₄(C₄H₁₀O₂)]_n, there are two coordination types for the four independent Na⁺ cations: two Na⁺ cations bond to six diolate O atoms [Na—O = 2.305 (2)–2.609 (2) Å], while the other two are five‐coordinate via one 1,4‐butane­diol [2.289 (2) and 2.349 (3) Å] and four diolate O atoms [2.295 (2)–2.408 (2) Å]. Corresponding to this, there are three‐ and four‐coordinate diolate O atoms, the latter bridging Na atoms. The 1,4‐butane­diol mol­ecules lie on inversion centres. The boron stereochemistry shows minor local perturbations from its usual tetrahedral state [B—O = 1.457 (4)–1.503 (4) Å]. The resulting polymer packs as sheets parallel to the (10) plane crosslinked by the butane­diol mol­ecules. The structure was solved using data from a multiple crystal.     

Comparison between various Keggin and Wells–Dawson sandwich‐type polyoxometalates in catalytic oxidation of cyclooctene and cyclohexene with hydrogen peroxide

The catalytic performance of tetra‐n‐butylammonium salts of Keggin and Wells–Dawson sandwich‐type polyoxotungstates, [M₄(PW₉O₃₄)₂]^m? and [M₄(P₂W₁₅O₅₆)₂]^n? (M = Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Zn²⁺), in the oxidation of cyclooctene and cyclohexene with 30% hydrogen peroxide under various conditions was investigated. In comparison, Wells–Dawson sandwich‐type polyoxometalates were found to be less active than Keggin ones. In both of them, those containing Zn and Fe gave higher conversions for different oxidation conditions. These catalysts showed very good reusability in the oxidation reaction. Copyright © 2014 John Wiley & Sons, Ltd.     

Self‐Assembly of [B‐SbW9O33]9− Subunit with Transition Metal Ions (Mn2+, Cu2+, Co2+) in Aqueous Solution: Syntheses,Structures and Magnetic Properties of Sandwich Type Polyoxometalates with Subvalent SbIII Heteroatom

Rational self‐assembly of Sb₂O₃ and Na₂WO₄, or (NH₄)₁₈[NaSb₉W₂₁O₈₆] with transition‐metal ions (Mn²⁺, Cu²⁺, Co²⁺), in aqueous solution under controlled conditions yield a series of sandwich type complexes, namely, Na₂H₂[Mn_2.5W_1.5(H₂O)₈(B‐β‐SbW₉O₃₃)₂]?32 H₂O (1) , Na₄H₇[Na₃(H₂O)₆Mn₃(μ‐OAc)₂(B‐α‐SbW₉O₃₃)₂]?20 H₂O (OAc=acetate anion) (2) , NaH₈[Na₂Cu₄Cl(B‐α‐SbW₉O₃₃)₂]?21 H₂O (3) , Na₈K[Na₂K(H₂O)₂{Co(H₂O)}₃(B‐α‐SbW₉O₃₃)₂]? 10 H₂O (4) , and Na₅H[{Co(H₂O)₂}₃W(H₂O)₂(B‐β‐SbW₉O₃₃)₂]?11.5 H₂O (5) . These structures are determined by using the X‐ray diffraction technique and further characterized by obtaining IR spectra and performing elemental analysis. Structure analysis reveals that polyoxoanions in 1 and 5 comprise of two [B‐β‐SbW₉O₃₃]^9? building units, whereas 2 , 3 , and 4 consist of two isomerous [B‐α‐SbW₉O₃₃]^9? building blocks, which are all linked by different transition‐metal ions (Mn²⁺, Cu²⁺, or Co²⁺) with different quantitative nuclearity. It should be noted that compound 2 represents the first one‐dimensional sinusoidal chain based on sandwich like tungstoantimonate building blocks through the carboxylate‐bridging ligands. Additionally, 3 is constructed from sandwiched anions [Na₂Cu₄Cl(B‐α‐SbW₉O₃₃)₂]^9? linked to each other to form an infinitely extended 2D network, whereas 5 shows an interesting 3D framework built up from offset sandwich type polyoxoanion [{Co(H₂O)₂}₃W(H₂O)₂(B‐β‐SbW₉O₃₃)₂]^6? linked by Co²⁺ and Na⁺ ions. EPR studies performed at 110 K and room temperature reveal that the metal cations (Mn²⁺, Cu²⁺, Co²⁺) reside in a square‐pyramidal geometry in 2 , 3 , and 4 . The magnetic behavior of 1 – 4 suggests the presence of weak antiferromagnetic coupling interactions between magnetic metal centers with the exchange integral J=?0.552 cm^?1 in 2 .     

[Bi4]6– – The Zintl Anion with the Highest Charge per Atom Obtained from Solution

From the dark‐purple solution of the Zintl phase KBi in liquid ammonia dark‐blue crystals of the ammonia solvate K₆[Bi₄](NH₃)₈ were obtained. In contrast to known Bi_n polyanions the chemical bond in the anion [Bi₄]^6– is in accordance with the (8‐N) rule featuring solely Bi–Bi single bonds. [Bi₄]^6– is a butane‐analog valence compound, and with 6 negative charges per 4 atoms it is the anion with the highest known charge per atom obtained from solution. The planarity of the trans‐[Bi₄]^6– unit hints at π orbital contributions of the bismuth atoms. The corresponding reactions of the phases K₅Bi₄ and K₃Bi₂ in liquid ammonia in the presence of [2.2.2]crypt(4, 7, 13, 16, 21, 24‐hexaoxa‐1, 10‐diazabicyclo‐[8.8.8]hexacosane) lead to the salt [K([2.2.2]crypt)]₂[Bi₂](NH₃)₄ with the known electron‐deficient [Bi₂]^2– polyanion and a Bi=Bi double bond.     

Gas‐phase fragmentation of metal adducts of alkali‐metal oxalate salts

Upon collisional activation, gaseous metal adducts of lithium, sodium and potassium oxalate salts undergo an expulsion of CO₂, followed by an ejection of CO to generate a product ion that retains all three metals atoms of the precursor. Spectra recorded even at very low collision energies (2 eV) showed peaks for a 44‐Da neutral fragment loss. Density functional theory calculations predicted that the ejection of CO₂ requires less energy than an expulsion of a Na⁺ and that the [Na₃CO₂]⁺ product ion formed in this way bears a planar geometry. Furthermore, spectra of [Na₃C₂O₄]⁺ and [³⁹K₃C₂O₄]⁺ recorded at higher collision energies showed additional peaks at m/z 90 and m/z 122 for the radical cations [Na₂CO₂]^+? and [K₂CO₂]^+?, respectively, which represented a loss of an M^? from the precursor ions. Moreover, [Na₃CO₂]⁺, [³⁹K₃CO₂]⁺ and [Li₃CO₂]⁺ ions also undergo a CO loss to form [M₃O]⁺. Furthermore, product‐ion spectra for [Na₃C₂O₄]⁺ and [³⁹K₃C₂O₄]⁺ recorded at low collision energies showed an unexpected peak at m/z 63 for [Na₂OH]⁺ and m/z 95 for [³⁹K₂OH]⁺, respectively. An additional peak observed at m/z 65 for [Na₂¹⁸OH] ⁺ in the spectrum recorded for [Na₃C₂O₄]⁺, after the addition of some H₂¹⁸O to the collision gas, confirmed that the [Na₂OH] ⁺ ion is formed by an ion–molecule reaction with residual water in the collision cell. Copyright © 2014 John Wiley & Sons, Ltd.     

Enhanced Separation of Potassium Ions by Spontaneous K+‐Induced Self‐Assembly of a Novel Metal–Organic Framework and Excess Specific Cation–π Interactions

A novel metal–organic framework (MOF) was fabricated by spontaneous K⁺‐induced supramolecular self‐assembly with the embedded tripodal ligand units. When the 3D ligand was loaded onto Fe₃O₄@mSiO₂ core‐shell nanoparticles, it could effectively separate K⁺ ions from a mixture of Na⁺, K⁺, Mg²⁺, and Ca²⁺ ions through nanoparticle‐assisted MOF crystallization into a Fe₃O₄@mSiO₂@MOF hybrid material. Excess potassium ions could be extracted because of the specific cation–π interaction between K⁺ and the aromatic cavity of the MOF, leading to enhanced separation efficiency and suggesting a new application for MOFs.     

Bis[μ3‐1,8‐bis(triisopropylsilylamido)naphthalene]bis(tetrahydrofuran)di‐μ3‐oxido‐dimanganese(III)disodium

The solid‐state structure of the title compound, [Na₂Mn₂(C₃₂H₅₆N₂OSi₂)₂O₂] or [1,8‐C₁₀H₆(NSiⁱPr₃)₂Mn(μ₃‐O)Na(THF)]₂, which lies across a crystallographic twofold axis, exhibits a central [Mn₂O₂Na₂]⁴⁺ core, with two oxide groups, each triply bridging between the two Mn^III ions and an Na⁺ ion. Additional coordination is provided to each Mn^III centre by a 1,8‐C₁₀H₆(NSiⁱPr₃)₂ [1,8‐bis(triisopropylsilylamido)naphthalene] ligand and to the Na⁺ centres by a tetrahydrofuran molecule. The presence of an additional Na...H—C agostic interaction potentially contributes to the distortion around the bridging oxide group.     

Hydrogen‐bonded and π‐interaction assembly in two 8‐alkoxycarbonyl‐1,8‐diazabicyclo[5.4.0]undec‐7‐enium chloride salts

The crystal structures of 8‐phenoxycarbonyl‐1,8‐diazabicyclo[5.4.0]undec‐7‐enium chloride, C₁₆H₂₁N₂O₂⁺·Cl⁻, (I), and 8‐methoxycarbonyl‐1,8‐diazabicyclo[5.4.0]undec‐7‐enium chloride monohydrate, C₁₁H₁₉N₂O₂⁺·Cl⁻·H₂O, (II), recently reported by Carafa, Mesto & Quaranta [Eur. J. Org. Chem. (2011), pp. 2458–2465], are analysed and discussed with a focus on crystal interaction assembly. Both compounds crystallize in the space group P2₁/c. The crystal packings are characterized by dimers linked through π–π stacking interactions and intermolecular nonclassical hydrogen bonds, respectively. Additional intermolecular C—H...Cl interactions [in (I) and (II)] and classical O—H...Cl hydrogen bonds [in (II)] are also evident and contribute to generating three‐dimensional hydrogen‐bonded networks.