Crystal structure, thermal behavior and vibrational studies of tetraethylammonium dihydrogenarsenate bis-arsenic acid [(C2H5)4N].[H2AsO4].[H3AsO4]2

An organic-inorganic hybrid compound of tetraethylammonium dihydrogenarsenate bis-arsenic acid salts of formula [(CH3CH2)4N].[H2AsO4].[H3AsO4]2(TEAs) were grown by the slow evaporation and characterized by means of single crystal X-ray diffraction, thermal analysis, FT-IR and Raman spectroscopy. This compound crystallize in the space groups Cc with unit cell parameters, a= 20.105(2) Å; b= 7.342(4) Å, c = 15.292(2) Å, γ = 115(4)°, Z = 4, R= 0.07. The structure has solved using direct methods and refined by least-squares analysis. In this case, the structure consists of infinite parallel two-dimensional planes built of mutually H2AsO4−, H3AsO4 tetrahedra connected by strong O-H···O hydrogen bonding. The thermoanalytical properties were studied using TG of TEAs method in the temperature ranges from 300 to 440 K for this hygroscopic sample. DSC measurement was carried out in the temperature range from 305 to 425 K

Synthesis, Crystal Structure and Characterization of [(CH3 CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O)

Single crystals of [(CH3CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O) were grown by the slow evaporation technique and characterized by means of single-crystal X-ray diffraction, FT-IR and Raman spectroscopy. The title compound belongs to the triclinic space group P with the following unit cell dimensions: a =7.5425(4) Å, b=9.8464 Å, c=13.7671(6) Å, α=89.951(3)°,β=89.753(3)°, γ=81.861(3)°, Z=4. These structures have solved using direct methods and refined by least-squares analysis. The structure was solved by the direct method and refined to final R value of 0.0567. The projection of [(CH3CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O) in the plan (a,b) shows an arrangement in layers perpendicular to the direction b . The structure consists of infinite parallel two-dimensional planes built connected ions and water molecules by strong O-H…O and O-H…Cl hydrogen bonding

catena-Poly[bis­(dibenzyl­ammonium) [[dichloridomercurate(II)]-μ-sulfato-κ2 O:O′]]

The structure of the title compound, (C14H16N)2[HgCl2(SO4)], consists of an infinite chain propagating along the c direction, containing HgII ions tetra­coordinated by two bridging O atoms of bis-monodentate sulfate anions and two chloride ligands. In the the crystal, N—H⋯O hydrogen bonding between the cations and the anionic chains consolidates the packing. The crystal structure was determined from an inversion twin with approximately equal twin domains

Crystal structure and spectroscopic study of bis-tetrapropylammonium hexachlorodicuprate(II), [N(C3H7)4]2Cu2Cl6

Single crystals of the bis-tetrapropylammonium hexachlorodicuprate(II), [N(C3H7)4]2Cu2Cl6, were grown by slow evaporation solution technique at room temperature. The compound was characterized by Raman, IR and single crystal X-ray diffraction studies. Crystal data for C12H28Cl3CuN (M = 356.24 g/mol): triclinic, space group P-1 (no. 2), a = 9.3851(2) Å, b = 9.3844(2) Å, c = 11.8837(3) Å, α = 106.3330(11)°, β = 100.0280(12)°, γ = 113.2830(12)°, V = 872.95(3) Å3, Z = 2, T = 293(2) K, μ(MoKα) = 1.693 mm-1, Dcalc = 1.355 g/mm3, 8056 reflections measured (6.64 ≤ 2Θ ≤ 62.02), 5526 unique (Rint = 0.0303) which were used in all calculations. The final R1 was 0.0427 (>2σ(I)) and wR2 was 0.1312 (all data). The atomic arrangement can be described by alternating organic and inorganic layers parallel to the (101) plan, made up of tetrapropylammonium groups and Cu2Cl6 dimers, respectively. In crystal structure, the inorganic layers, built up by Cu2Cl6 dimers, are connected to the organic ones through hydrogen bonding C-H…Cl and Van der Waals interaction in order to build cation-anion-cation cohesion. These interactions cause to the formation of a three-dimensional supramolecular architecture

Bis(1,1-dimethyl­guanidinium) tetra­aqua­dimethyl­tin(IV) bis­(sulfate)

Single crystals of the title salt, (C3H10N3)2[Sn(CH3)2(H2O)4](SO4)2, formed concomitantly with the already known [Sn(CH3)3]2SO4·2H2O. In the title structure, the SnIV atom displays a slightly distorted octa­hedral coordination geometry defined by four O water atoms in the equatorial positions and two methyl groups in the axial positions. In the crystal, various O—H⋯O and N—H⋯O hydrogen-bonding inter­actions between the organic cation and the coordinated water mol­ecules as donors and the sulfate O atoms as acceptors result in a three-dimensional structure. The SnIV atom is located on an inversion centre, resulting in half of the complex metal cation being in the asymmetric unit

CRYSTAL STRUCTURES OF TWO PHOSPHONATE SALTS: MONOCYCLOHEXYLAMMONIUM HYDROGEN PHOSPHONATE AND MONOCYCLOHEXYLAMMONIUM PHENYL PHOSPHONATE

Hydrogen phosphonate anions and monocyclohexylammonium cations interacting through hydrogen bonds conduct to the formation of a salt namely monocyclohexylammonium hydrogen phosphonate. In this structure, hydrogen phosphonate anions are linked by pairs through O—H···O hydrogen bonds leading to anionic dimers. Each dimer is connected to its two neighbours through cations via N—H···O hydrogen bonds leading to infinite chains which are then connected by N—H···O hydrogen bonds giving rise to a layered structure. The phenyl phosphonates form dimers that are connected through an expended hydrogen bonding network involving the cations into a layer

CRYSTAL STRUCTURES OF TWO PHOSPHONATE SALTS: MONOCYCLOHEXYLAMMONIUM HYDROGEN PHOSPHONATE AND MONOCYCLOHEXYLAMMONIUM PHENYL PHOSPHONATE

Hydrogen phosphonate anions and monocyclohexylammonium cations interacting through hydrogen bonds conduct to the formation of a salt namely monocyclohexylammonium hydrogen phosphonate. In this structure, hydrogen phosphonate anions are linked by pairs through O—H···O hydrogen bonds leading to anionic dimers. Each dimer is connected to its two neighbours through cations via N—H···O hydrogen bonds leading to infinite chains which are then connected by N—H···O hydrogen bonds giving rise to a layered structure. The phenyl phosphonates form dimers that are connected through an expended hydrogen bonding network involving the cations into a layer

Temperature- and Light-Induced Spin Crossover Observed by X-ray Spectroscopy on Isolated Fe(II) Complexes on Gold

Using X-ray absorption techniques, we show that temperature- and light-induced spin crossover properties are conserved for a submonolayer of the [Fe(H2B(pz)2)2(2,2′-bipy)] complex evaporated onto a Au(111) surface. For a significant fraction of the molecules, we see changes in the absorption at the L2,3 edges that are consistent with those observed in bulk and thick film references. Assignment of these changes to spin crossover is further supported by multiplet calculations to simulate the X-ray absorption spectra. As others have observed in experiments on monolayer coverages, we find that many molecules in our submonolayer system remain pinned in one of the two spin states. Our results clearly demonstrate that temperature- and light-induced spin crossover is possible for isolated molecules on surfaces but that interactions with the surface may play a key role in determining when this can occur

Propriétés structurales et électroniques de sels de BEDT-TTF. Influence de la température et de la pression

Les sels conducteurs organiques basés sur la molécule BEDT-TTF présentent une gamme de comportements dont la diversité s'exprime par application de contraintes de température et de pression. La connaissance des prorpriétés structurales de ces sels en tout point du diagramme de phase s'avère indispensable à la compréhension de leurs propriétés physiques. La diffraction X à très basse température et haute pression demeure encore une voie d'investigation pionnière. Nous avons étudié les comportements structuraux et électroniques de plusieurs sels de BEDT-TTF aux conditions ambiantes mais aussi en variation de température (de 340K à 10K) et en variation de pression (de 1bar à 16kbar). En particulier, les structures cristallines sont déterminées en différents points du diagramme de phase et reliées aux changements de propriétés physiques.non disponibl

Crystallography and spin-crossover. A view of breathing materials

The spin-crossover phenomenon (SCO) is a fascinating field that potentially concerns any material containing a (d4-d7) transition metal complex finding therefore an echo in as diverse research fields as chemistry, physics, biology and geology. Particularly, molecular and coordination-polymers SCO solids are thoroughly investigated since their bistability promises new routes towards a large panel of potential applications including smart pigments, optical switches or memory devices. Notwithstanding these motivating applicative targets, numerous fundamental aspects of SCO are still debated. Among them, the investigation of the structure-property relationships is unfailingly at the heart of the SCO research field. All the facets of the richness of the structural behaviors shown by SCO compounds are only revealed when exploring the whole sample scales - from atomic to macroscopic - all the external stimuli - temperature, pressure, light and any combinations and derived perturbations - and the various forms of the SCO compounds in the solid state - crystalline powders, single-crystals, poorly crystalline or nano-sized particles. Crystallography allows investigating all these aspects of SCO solids. In the past few years, crystallography has certainly been in a significant phase of development pushing the frontiers of investigations, in particular thanks to the progress in X-ray diffraction techniques. The encounter between SCO materials and crystallography is captivating, taking advantages from each other. In this paper, a personal account mainly based on our recent results provides perspectives and new approaches that should be developed in the investigation of SCO materials