On the structures of X- and Y-type zeolites. Structural changes within the cavities of Na-Y during dehydration and contrasts with Na-X systems

Samples of dehydrated and partially dehydrated Na-Y were examined by X-ray diffraction methods revealing the progressive structural changes which occur as water is removed and the different behaviour compared with Na-X. The differences between Na-Y and Na-X reflect the reduced Al content of Na-Y and the consequential lower average capability of each framework oxygen atom for balancing cation charges. In the small-pore region of Na-Y, the total number of Na atoms remains relatively constant during dehydration (ca. 15 per unit cell compared withca. 18 in Na-X); unlike Na-X, Na-Y, has no site I atoms. Significant dehydration of the small-pore region, and the change from low to high site II occupancy, do not occur until the total water content of the sample is less than that which pertains under atmospheric conditions. In the 12-ring regionn of Na-Y, [Na(H₂O)₂]⁺ units are observed at an intermediate level of dehydration, possibly linked by water molecules astride the site III region to networks in adjacent 12-rings. There is no build-up, as in Na-X, of Na at site III, and site IIB (=III) is (at least partially) occupied by H₂O rather than Na. Further dehydration progressively removes H₂O but there is little rearrangement of Na atom positions, except the build-up in site II which accounts for much of the loss of Na from the mobile phase.     

Cs2.91Na1.34Fe3+0.25[Fe3O(SO4)6(H2O)3]·5H2O,a member of the Maus's salt family

The title compound, tricaesium sodium iron(III) μ₃‐oxido‐hexa‐μ₂‐sulfato‐tris[aquairon(III)] pentahydrate, Cs_2.91Na_1.34Fe³⁺_0.25[Fe₃O(SO₄)₆(H₂O)₃]·5H₂O, belongs to the family of Maus's salts, K₅[Fe₃O(SO₄)₆(H₂O)₃]·6H₂O, which is based on the triaqua‐μ₃‐oxido‐hexa‐μ‐sulfato‐triferrate(III) anion, [Fe₃O(SO₄)₆(H₂O)₃]⁵⁻, with Fe in a characteristically distorted octahedral coordination environment, sharing a common corner via an oxide O atom. Cs in four different cation sites, Na in three different cation sites and five water molecules link the anions in three dimensions and set up a crystal structure in which those parts parallel to (001) and within 0.05 < z < 0.95 have a distinct trigonal pseudosymmetry, whereas the cation arrangement and bonding near z∼ 0 generate a clear‐cut noncentrosymmetric polar edifice with the monoclinic space group C2. The structure shows some cation disorder in the region near z ∼ , where one Na atom in octahedral coordination is partly substituted by Fe³⁺, and a Cs atom is substituted by small amounts of Na on a separate nearby site. One Na atom, located on a twofold axis at z = 0 and tetrahedrally coordinated by four sulfate O atoms of two [Fe₃O(SO₄)₆(H₂O)₃]⁵⁻ units, plays a key role in generating the noncentrosymmetric structure. Three of the seven different cation sites are on twofold axes (one Na⁺ site and two Cs⁺ sites), and all other atoms of the structure are in general positions.     

A B3LYP study on counterpoise-corrected geometry optimizations for hydrated complexes of [K(H2O)n] and [Na(H2O)n]

We report the basis set dependencies and the basis set superposition errors for the hydrated complexes of K⁺ and Na⁺ ions in relation to the recent studies of the KcsA potassium channel. The basis set superposition errors are estimated by the geometry optimizations at the counterpoise-corrected B3LYP level. The counterpoise optimizations alter the hydration distances by about 0.02–0.03 Å. The enthalpies and free energies for K⁺ + n(H₂O) → [K(H₂O)_n]⁺ and Na⁺ + n(H₂O) → [Na(H₂O)_n]⁺ (n = 1–6) are compared between the theoretical and experimental values. The results show that the addition of diffuse functions to K, Na, and O species are effective. However, it is also found that the counterpoise corrections using diffuse functions work so as to underestimate the free energies for the complexes with increasing the hydration number. The stabilization energies in aqueous solution are larger for a Na⁺ ion than for a K⁺ ion, suggesting the contributions of their dehydration processes to the ion selectivity of the KcsA potassium channel. The changes in coordination distance between the isolated [K(H₂O)₈]⁺ and the [K(H₂O)₈]⁺ in the KcsA potassium channel indicate the importance of hydrogen bondings between the first hydration shell and the outer hydration shells.     

Strukturelle Untersuchungen an Cs2[B12H12]

Structural Investigations on Cs₂[B₁₂H₁₂] The crystal structure of Cs₂[B₁₂H₁₂] has been determined from X‐ray single‐crystal data collected at room temperature. Dicesium dodecahydro‐closo‐dodecaborate crystallizes as colourless, face‐rich crystals (cubic, Fm 3; a = 1128.12(7) pm; Z = 4). Its synthesis is based on the reaction of Na[BH₄] with BF₃(O(C₂H₅)₂) via the decomposition of Na[B₃H₈] in boiling diglyme, followed by subsequent separations, precipitations (with aqueous CsOH solution) and recrystallizations. The crystal structure is best described as anti‐CaF₂‐type arrangement with the Cs⁺ cations in all tetrahedral interstices of the cubic closest‐packed host lattice of the icosahedral [B₁₂H₁₂]^2–‐cluster dianions. The intramolecular bond lengths are in the range usually found in closo‐hydroborates: 178 pm for the B–B and 112 pm for the B–H distance. Twelve hydrogen atoms belonging to four [B₁₂H₁₂]^2– icosahedra provide an almost perfect cuboctahedral coordination sphere to the Cs⁺ cations, and their distance of 313 pm (12 ×) attests for the salt‐like character of Cs₂[B₁₂H₁₂] according to {(Cs⁺)₂([B₁₂H₁₂]^2–)}. The ¹¹B{¹H}‐NMR data in aqueous (D₂O) solution are δ = –12,70 ppm (¹J_B–H = 125 Hz), and δ = –15,7 ppm (linewidth: δν_1/2 = 295 Hz) for the solid state ¹¹B‐MAS‐NMR.     

Metastable ion decomposition and collisional activation mass spectra of 1,2,3-triarylpropen-1-ones

Substituents have been found to have a marked influence on the metastable ion decompositions and collisionally activated (CA) fragmentations of the M⁺˙ ion of a number of 1,2,3-triarylpropen-1-ones. An attempt has been made to confirm the structures of the rearrangement ions, [C₁₄H₁₀]⁺˙, [C₁₃H₁₁]⁺˙, [C₁₃H₉]⁺ and [C₁₂H₈]⁺˙ by comparison of their CA spectra with those of the corresponding ions produced from reference compounds. The results imply that [C₁₄H₁₀]⁺˙ and the M⁺˙ ions of phenanthrene and diphenylacetylene have a common structure, [C₁₃H₉]⁺ and the fluorenyl cation have a common structure and [C₁₂H₈]⁺˙ and biphenylene molecular ion have a common structure. The available data indicate that the ion at m/z 167 consists of a mixture of structures, likely possibilities being diphenylmethyl, phenyltropylium and dihydrofluorenyl cations.     

Mass spectrometry of aralkyl compounds with a functional group–X A reinvestigation of the structure of the [C8H9]+-ion from 1-phenylethylbromide and of the molecular ion [C8H8]+˙ from styrene by use of 13C labelling

Specific ¹³C-labelling in the side-chain of 1-phenylethylbromide and of styrene shows that it is not necessary to assume eight-membered ring structures for the [C₈H₉]⁺- and [C₈H₈]⁺⁺˙-ions to explain the almost complete randomization of all hydrogen atoms, as might be concluded from D-labelling data. It is now suggested that the eight-membered ring is predominantly present in [C₈H₉]⁺ and [C₈H₈]⁺˙ ions of low internal energy. In particular this appears to apply to styrene, which generates a cyclooctatetraene molecular ion with the original side-chain carbon atoms still linked together, as shown by ^13C-labelling.     

Preparation of Cyclodextrin–Iron Species in Water by Laser Ablation: Secondary Ion Mass Spectrometry

Supramolecular complexes between cyclodextrin and iron species are studied by using secondary ion mass spectrometry. The iron species are prepared by pulsed‐laser ablation of bulk iron in water; this gives Fe⁺ (56 m/z) and Fe_xO_y⁺ (x, y=1–7) species. Cyclodextrin is added to the water either before or after the laser ablation. When it is added before laser ablation, molecular fragments of cyclodextrin are detected as dehydrated glucopyranose units (C₆H₈O₄⁺) associated with Fe⁺, FeO⁺, and Fe₂O⁺ species. The focus is to observe supramolecular host–guest complexes or adducts between intact molecules of cyclodextrin and iron species. When cyclodextrin is added after laser ablation, the relevant peak at 1210 m/z is observed and assigned as C₄₂H₆₇O₃₅FeNa⁺, which corresponds to a cyclodextrin molecule minus three H atoms. Two possible explanations of this finding are the presence of the host–guest C₄₂H₆₇O₃₅Na–Fe complex, in which Fe is in the cavity, or the presence of the adduct C₄₂H₆₇O₃₄Na–FeO with FeO on the outer surface; the formation of these complexes are supported by the hydrophobicity of Fe and hydrophilicity of FeO, respectively. Due to the presence of 12 % of intact C₄₂H₇₀O₃₅Na–Fe complex and an estimated Fe/FeO ratio of approximately 10², host–guest formation is assumed to be more significant.     

A comparison of the unimolecular decomposition pathways of some C7 and C8 ions in the gas phase

[CnH_2n?3]⁺ and [C_nH_2n?4]⁺·(n = 7, 8) ions have been generated in the mass spectrometer from C_nH_2n?3 Br (n = 7, 8) precursors and from two steroids. The relative abundances of competing ‘metastable transitionss’ indicate (partial) isomerization to a common structure (or mixture of structures) prior to decomposition in most examples of all four types of ions. In contrast, [C₈H₁₀O]⁺· and [C₈H₁₂O]⁺· ions, generated from different sources as molecular ions and by fragmentation of steroids, do not decompose through common-intermediates.     

Synthesis and Crystal Structures of Alkali and Alkaline Earth Metal Complexes of 3,5-Dinitropyrazolyl-4-carboxylate

The synthesis and crystal structures of 3,5-dinitro-1H-pyrazolyl-4-carboxylic acid (H₂dnpzc) and its four complexes with Ca²⁺, Ba²⁺, Na⁺ and K⁺ are reported in this paper. Ca(dnpzc) · 5H₂O exhibits a 1D polymeric structure, whereas Ba(dnpzc) · 4H₂O possesses a 2D structure. The structure of Na₂(dnpzc) · 4H₂O consists of 2D layers of [Na(dnpzc)]^–_n and 1D chains of [Na(H₂O)₃]⁺_n. K₂(dnpzc) · H₂O has a true 3D structure. It was observed that the doubly deprotonated ligand (dnpzc^2–) can act as a versatile bridge to form polymeric structures by varying combinations of its 8 potential donor atoms (two carboxy O atoms, two pyrazolyl N atoms and four nitro O atoms). Particularly in the structure of K₂(dnpzc) · H₂O, all the 8 donor atoms of dnpzc^2– take part in the coordination and as many as 10 potassium atoms are connected by one ligand.     

exo/endo-Selectivity in the Reaction of ‘Bare’ FeO+ with Bicyclo[2.2.1]heptane (Norbornane)

‘Bare’ FeO⁺ reacts in the gas phase with norbornane with collision efficiency, and the most prominent cationic products correspond to [FeC₅H₆]⁺ (32%), [FeC₇H₈]⁺ (19%), [FeC₃H₆O]⁺ (19%) and [FeC₆H₆]⁺ (14%), which are structurally characterized by ligand exchange as well as collision-induced dissociation experiments. Circumstantial evidence is provided which indicates that the complexes [FeC₅H₆]⁺, [FeC₇H₈]⁺, and [FeC₆H₆]⁺ originate from an Fe(norbornene)⁺ intermediate which itself is formed by elimination of H₂O from the [FeO(norbornane)]⁺ encounter complex. Although the reactions are preceded and/or accompanied by partial H/D exchange, the isotope distribution in the productions clearly points to a preferential endo-attack of bare FeO⁺, with an endo/exo-ratio of ca. 10.3 and kinetic isotope effects k_H/k_D for the endo-abstraction of 2.4 and of 7.7 for approaching an exo-C? H bond. The preferred endo-approach of bicyclo[2.2.1]heptane by ‘bare’ FeO⁺ is in distinct contrast to the P-450-mediated or the iron(III)porphyrin-catalyzed hydroxylation of this substrate which favor reactions at the exo-face.     

The consecutive loss of two H2O molecules from protonated 1,2- and 1,3- cyclohexanediols in the gas phase: An example for the incidence of skeletal rearrangement in chemical ionization mass spectrometry

The consecutive dehydration of protonated molecules [MH]⁺ of 1,2- and 1,3-cyclohexanediols (cis and trans isomers) by loss of two H₂O molecules has been investigated. Analysis of ²H labelled compounds showed that loss of the first H₂O molecule represents a simple heterolysis, i.e. a dissociation without exchange of hydrogens between O—H and C—H bonds. Subsequent elimination of the second H₂O molecule in the process [MH–H₂O]⁺→[MH–2H₂O]⁺ followed several competing paths. The two major ones corresponded formally (with reference to an intact 6-ring skeleton) to 1,3- and 1,4-eliminations; in comparison, the alternative 1,2-elimination is only a minor route at most. At least for the 1,3-elimination, water loss from the [MH–H₂O]⁺ ions is not direct, but is associated with skeletal rearrangement, most probably of the Wagner-Meerwein-type, effecting contraction of the 6- to a 5-membered ring.     

On the unimolecular loss of acetylene from metastable C11H9]+ ions

Extensive ¹³C labelling experiments demonstrate that loss of acetylene from metastable [C₁₁H₉]⁺ ions is a complex process, which can be described quantitatively in terms of a four-parameter model. The major reaction path (77.8%) involves scrambling of all 11 carbon atoms. Insight into the reaction details is provided neither by the kinetic energy release associated with the reaction [C₁₁H₉]⁺ → [C₉H₇]⁺ + C₂H₂ nor by the analysis of the collisional activation mass spectra of the resulting [C₉H₇]⁺ ions.     

Site Preference in Multimetallic Nanoclusters: Incorporation of Alkali Metal Ions or Copper Atoms into the Alkynyl‐Protected Body‐Centered Cubic Cluster [Au7Ag8(C≡CtBu)12]+

The synthesis, structure, substitution chemistry, and optical properties of the gold‐centered cubic monocationic cluster [Au@Ag₈@Au₆(C≡C^tBu)₁₂]⁺ are reported. The metal framework of this cluster can be described as a fragment of a body‐centered cubic (bcc) lattice with the silver and gold atoms occupying the vertices and the body center of the cube, respectively. The incorporation of alkali metal atoms gave rise to [M_nAg_8?nAu₇(C≡C^tBu)₁₂]⁺ clusters (n=1 for M=Na, K, Rb, Cs and n=2 for M=K, Rb), with the alkali metal ion(s) presumably occupying the vertex site(s), whereas the incorporation of copper atoms produced [Cu_nAg₈Au_7?n(C≡C^tBu)₁₂]⁺ clusters (n=1–6), with the Cu atom(s) presumably occupying the capping site(s). The parent cluster exhibited strong emission in the near‐IR region (λ_max=818 nm) with a quantum yield of 2 % upon excitation at λ=482 nm. Its photoluminescence was quenched upon substitution with a Na⁺ ion. DFT calculations confirmed the superatom characteristics of the title compound and the sodium‐substituted derivatives.     

Substituent effects in the mass spectra of diethyl phenyl phosphates

The mass spectra of diethyl phenyl phosphates show substituent effects with electron-donating groups favouring the molecular ion M⁺˙, and the [M? C₂H₄]⁺˙, [M – 2C₂H₄]⁺˙ and [XPhOH]⁺˙ ions. The [PO₃C₂H₆]⁺ (m/z 109) and [PO₃H₂]⁺ (m/z 81) ions are favoured by electron-withdrawing groups. Results suggest that the formation of the [XPhC₂H₃]⁺˙ ion involves rearrangement of C₂H₃ to the position ortho to the phosphate group. Ortho effects are also observed.     

catena‐Poly[tris(ethylenediamine‐κ2N,N′)nickel(II) [[trithiocyanato‐κ3N‐sodium(I)]‐μ‐aqua‐κ2O:O]]

The title complex, {[Ni(C₂H₈N₂)₃][Na(NCS)₃(H₂O)]}_n, con­sists of discrete [Ni(en)₃]²⁺ dications (en is ethyl­enedi­amine) and polymeric [(H₂O)_0.5Na(NCS)₃(H₂O)_0.5]_n^2n? anions. The compound crystallizes in space group Pc1. The Ni^II atom lies on a threefold axis and has a distorted octahedral coordination geometry. The Na⁺ cation also lies on a site with imposed crystallographic threefold symmetry and is coordinated by the thio­cyanate N atoms (the thio­cyanates are in general posi­tions), by one water mol­ecule with crystallographically imposed 32 symmetry and by a second water mol­ecule with crystallographically imposed symmetry. The unique Na atom thus has trigonal–bipyramidal coordination. The O atoms of the water mol­ecules bridge the Na⁺ cations to form one‐dimensional polymeric chains in the crystal structure. The [Ni(en)₃]²⁺ dications are distributed around and between the chains and are linked to them via N—H?S hydrogen bonds.     

The Water-Rich Iodidobismuthate (H3O)Rb3BiI7·4H2O

Red cuboid crystals of the water-rich iodidobismuthate(III) (H₃O)Rb₃BiI₇ · 4H₂O crystallize from a solution of RbI and BiIO in concentrated aqueous HI at ambient conditions. X-ray diffraction reveale an orthorhombic structure with space group Pnma (no. 62). In the crystal structure, [BiI₆]^3– octahedra are arranged in layers parallel to (010). Nine-fold coordinated Rb⁺ and additional I^– ions connect the iodidobismuthate(III) groups into a three-dimensional framework, which hosts protonated water complexes ¹_∞[H₁₁O₅]⁺, i.e. infinite zigzag chains of hydrogen-bonded water molecules and oxonium cations. (H₃O)Rb₃BiI₇ · 4H₂O decomposes in air at ambient temperature within few days, resulting in fragmentation and amorphization of the crystals. Fast and complete dehydration occurs between 50 °C and 100 °C. Hydrates like this are possible intermediates in the slow hydrolysis of bismuth-based halide perovskites, which are currently discussed as lead-free alternatives to the solar cell absorber material methylammonium lead triiodide (MAPI).     

The first example of a mixed alkoxide hydride of boron: sodium boron isopropoxide trihydride

The title compound, poly[[μ‐trihydro(isopropoxy)borato]sodium(I)], [Na(C₃H₁₀BO)]_n, forms unique polymeric layers normal to the c axis via Na⁺...O [2.3405 (15) Å] and Na⁺...H(borane) [2.22 (3) and 2.28 (3) Å] interactions. This arrangement builds on distorted tetrahedral Na⁺, oxygen and boron environments, with one of the borane hydride units uncoordinated, and highlights potential H₃B—O‐based chemistry.     

Electron ionization mass spectrometry of systematically modified ligands in chromium(III) β-diketonates

The positive ion mass spectra of several chromium(III) β-diketonates with aliphatic α-substituents have been investigated. Metastable peaks in the spectra confirm that ions containing substituents with γ-H atoms undergo propene loss. This implies a McLafferty rearrangement of an open-chain ligand structure. Ethyl radicals are lost from n-butyl substituents; methyl groups are cleaved from the molecular ions of complexes formed from methyl-substituted ligands. The main fragment is, as expected, [ML₂]⁺; however, its further fragmentation is different from that of [ML₃]⁺. Electron donating substituents stabilize doubly charged molecular ions.     

Bis{[phthalocyaninato(2–)]arsenic(III)} tetradecaiodotetraarsenic(III)

Crystals of the novel title arsenic(III) phthalocyanine complex, [As(C₃₂H₁₆N₈)]₂[As₄I₁₄] or [(AsPc)⁺]₂·[As₄I₁₄]²⁻, where Pc is phthalocyaninate(2−), have been obtained by the reaction of pure powdered As with phthalo­nitrile under a stream of iodine vapour at 493 K. The crystals are built up of separate but interacting [AsPc]⁺ cations and [As₄I₁₂]²⁻ anions. The As atom of the [AsPc]⁺ unit is bonded to the four iso­indole N atoms of the Pc macrocycle and lies 0.743 (2) Å out of the plane defined by these four N atoms. The anionic part of the complex consists of AsI₃ and [AsI₄]⁻ units joined together into an [As₄I₁₄]²⁻ anion. The arrangement of the oppositely charged moieties, [AsPc]⁺ and [As₄I₁₄]²⁻, in the crystal is determined mainly by ionic attraction and by donor–acceptor interactions between the [AsPc]⁺ and [As₄I₁₄]²⁻ ions.     

Molecular states formed by ion beam neutralization of [C2H2]+ and [C2H3]+ on metal targets

A combination of charge-stripping and beam-scattering techniques has been used to study the molecular states formed when a fast beam of [C₂H₂]⁺ and [C₂H₃]⁺ in several isotopic forms are neutralized by electron transfer from metal target atoms (K, Na, Mg and Zn). For [C₂H₃]⁺ the isotopic compositions and relative abundances of product states were found to be insensitive to the method of ion preparation (electron impact and chemical ionization). Ground state neutrals are formed in partial abundance when Mg or Zn is used as a target atom. With low ionization potential targets (K and Na) excitel dissociative states of C₂H₂ and C₂H₃ are formed as major beam constituents. For these states decomposition products have been identified and fragmentation energies measured. The excited states of C₂H₂ and C₂H₃ lie alout 6.8 eV and 2.9 eV, respectively, above their stable ground states. The discussion focuses on the possible identity of the excited states and their structural relations to the precursor ions.