ABSTRACT
The hybrid compound [Cu(cyclam)(H2O)2]0.5[{Cu(cyclam)}1.5{B-H2As2Mo6O26(H2O)}]·9H2O (1) (cyclam = 1,4,8,11-tetraazacyclotetradecane) was synthesized in aqueous solution by reacting the {Cu(cyclam)}2+ complex with a mixture of heptamolybdate and an arsenate(V) source. Crystal packing of 1 exhibits a supramolecular open-framework built of discrete covalent molybdoarsenate/metalorganic units and additional [Cu(cyclam)(H2O)2]2+ cations, the stacking of which generates squarelike channels parallel to the z axis with an approximate cross section of 10 × 11 Å2 where all the hydration water molecules are hosted. Thermal evacuation of solvent molecules yields a new anhydrous crystalline phase, but compound 1 does not preserve its single-crystalline nature upon heating. However, when crystals are dehydrated under vacuum, they undergo a structural transformation that proceeds via a single-crystal-to-single-crystal pathway, leading to the anhydrous phase [{Cu(cyclam)}2(A-H2As2Mo6O26)] (2). Total dehydration results in important modifications within the inorganic cluster skeleton which reveals an unprecedented solid-state B to A isomerization of the polyoxoanion. This transition also involves changes in the CuII bonding scheme that lead to covalent cluster/metalorganic layers by retaining the open-framework nature of 1. Compound 2 adsorbs ambient moisture upon air exposure, but it does not revert back to 1, and the hydrated phase [{Cu(cyclam)}2(A-H2As2Mo6O26)]·6H2O (2h) is obtained instead. Structural variations between 1 and 2 are reflected in electron paramagnetic resonance spectroscopy measurements, and the permanent microporosity of 2 provides interesting functionalities to the system such as the selective adsorption of gaseous CO2 over N2.
ABSTRACT
The crystal structure, Hirshfeld surface analysis and spectroscopic analysis of a new polyoxometalate (POM) compound, namely, nonakis(2-methoxyaniline) bis(diphosphopentamolybdate) trihydrate, (C7H9NO)9[P2Mo5O23]2·3H2O, is reported. The title compound was synthesized using the solution method and was structurally characterized by single-crystal X-ray diffraction, which revealed P-1 symmetry. A study of the intermolecular interactions using Hirshfeld surface analysis confirmed that the hydrogen-bonding interactions play the dominant role in the stability of the crystal structure. The refinement was complicated by extensive disorder affecting 11 of the 16 ions and molecules in the asymmetric unit. IR and UV-Vis spectroscopic techniques were used to identify the vibrational modes and to classify this compound as an insulator.
ABSTRACT
The crystal structure and the results of theoretical calculations for the new organoarsenate salt o-anisidinium dihydroarsenate (systematic name: 2-methoxyanilinium dihydrogen arsenate), C7H10NO+·H2AsO4-, are reported. The salt, crystallizing in the triclinic space group P-1, was synthesized using a solution method and was characterized by single-crystal X-ray diffraction analysis. It possesses a layered supramolecular architecture in the crystal. The intermolecular interactions were studied using Hirshfeld surface analysis which confirmed that hydrogen bonds and H...H contacts play dominant roles in the crystal structure of the investigated system. An analysis of the electronic structure and molecular modelling using charge distribution confirms the good electrophilic reactivity of the title compound.
ABSTRACT
A detailed description of the crystal structure and a Hirshfeld surface analysis of the new heteropolyoxometalate compound (C6H8N)5[HAs2Mo6O26(H2O)]·3H2O are reported. The title compound was synthesized using solution methods and its structure was characterized by single-crystal X-ray diffraction. The investigated compound contains a new [HAs2Mo6O26(H2O)]5- polyanion and crystallizes in the monoclinic space group P21/c. The crystallographic analysis provided an understanding of the architecture and structural features of the complex crystal lattice and the Hirshfeld surface analysis shed more light on the intermolecular interactions occurring in the crystal.
ABSTRACT
We report a complex study on the crystal structures, electronic properties, reactivity and dynamics of three polyoxometalate compounds (C6NH8)4[H2P2Mo5O23]·5H2O (1), (C2H8N)5[HP2Mo5O23]·(C3H9NO2)0.5·(H2O)1.5 (2) and (C2H8N)3[PMo12O40]·(H2O)0.34 (3). These compounds were synthesized using a solution method and characterized by single-crystal X-ray diffraction. Crystallography confirmed three distinct symmetries P1[combining macron], P21/c and R3[combining macron]c for 1, 2, and 3, respectively, and unit cell constants a = 12.5609(2) Å, b = 13.2470(2) Å, c = 14.0353(2) Å, α = 107.1568(14)°, ß = 101.2854(13)°, γ = 92.1445(14)° for 1, a = 15.8583(6) Å, b = 17.3578(5) Å, c = 14.8499 (4) Å, ß = 114.933(3)° for 2, and a = 16.3798(3) Å, c = 50.2781(5) Å for 3. Semi-empirical calculations applied on the compounds provided information about their reactivity and electronic structures. In this context, several discussions concerning the frontier molecular orbitals, molecular electrostatic potential, thermodynamic properties and local ionization potential were mentioned. We also conducted molecular dynamics analysis in order to elucidate the dynamics of cations and anions and their energy variation.
ABSTRACT
The title compound, potassium strontium trialuminium tetra-arsenate, was prepared by solid-state reaction. The structure consists of AlO(6) octa-hedra (site symmetries 2.. and 2/m) and two AsO(4) tetra-hedra (.2. and m..) sharing corners and edges to form a two-dimensional structure parallel to (010). The cations are occupationally disordered and are located in the interlayer space. For both types of cations, distorted coordination polyhedra are observed.
ABSTRACT
A single crystal of NaMg(2)V(3)O(10) has been prepared by solid-state reaction at 1173â K. The [Mg(2)(V(3)O(10))](-) anions are built up from edge-sharing MgO(6) octa-hedra to form [Mg(4)O(18)] units, which are linked to each other by trivanadate groups (V(3)O(10)). The Na(+) ions are located in the tunnel space.
ABSTRACT
The title compound, sodium calcium trimagnesium tris-(arsenate), an alluaudite-like arsenate, was prepared by solid-state reaction at high temperature. The structure is built up from edge-sharing MgO(6) octa-hedra in chains associated with the AsO(4) arsenate groups. The three-dimensional network leads to two different tunnels occupied statistically by Na(+) and Ca(2+). One As and one Mg atom lie on twofold rotation axes; one Na and one Ca are disordered over two sites with occupancies of 0.7 and 0.3 and these sites lie on a twofold rotation axis and an inversion centre, respectively.
ABSTRACT
The single crystal of sodium manganese arsenate (1.72/3.28/12), Na(1.72)Mn(3.28)(AsO(4))(3), used for analysis was prepared by solid-state reaction at 1073 K. The compound crystallizes in the monoclinic system in space group C2/c. The structure consists of a complex network of edge-sharing MnO(6) octahedral chains, linked together by AsO(4) tetrahedra, forming two distinct channels, one containing Na(+) cations and the other occupied statistically by Mn(+) and Na(+) cations.
