scholarly journals The phase transition of rubidium hydrogen carbonate, RbHCO3

2017 ◽  
Vol 73 (7) ◽  
pp. 975-979 ◽  
Author(s):  
Carla Larvor ◽  
Berthold Stöger
Keyword(s):  
Phase Transition ◽  
Hydrogen Bonding ◽  
High Temperature ◽  
Hydrogen Atom ◽  
Low Temperature ◽  
Three Dimensional ◽  
Disorder Phase Transition ◽  
Dimensional Network ◽  
Hydrogen Carbonate ◽  
Index 2

Rubidium hydrogen carbonate, RbHCO3, features an order/disorder phase transition atTC= 245 K from the high-temperature (HT) disorderedC2/mmodification to the low-temperature (LT)C-1 modification. The crystal structures are characterized by [HCO3]22−pairs of hydrogen carbonate groups connected by strong hydrogen bonding. The [HCO3]22−pairs are connected by Rb+cations into a three-dimensional network. In HT-RbHCO3, the hydrogen atom is disordered. In LT-RbHCO3, ordering of the hydrogen atom leads to atranslationengleichesymmetry reduction of index 2. The lost reflections and rotations are retained as twin operations.

scholarly journals The order/disorder phase transition of hypophosphorous acid H3PO2

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Martin Nastran ◽  
Berthold Stöger
Keyword(s):  
Phase Transition ◽  
Hydrogen Bonding ◽  
High Temperature ◽  
Low Temperature ◽  
Hydrogen Bonds ◽  
Rotation Axis ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Hypophosphorous Acid ◽  
Disorder Phase Transition

Abstract Hypophosphorous acid, H3PO2 is dimorphic with a phase transition in the 200–225 K range. The H3PO2 molecules are connected by hydrogen bonding to infinite chains extending in the [100] direction. In the high-temperature phase (P21212, Z ′ = 1 2 ${Z}^{\prime }=\frac{1}{2}$ ), the hydrogen bonds are disordered about a two-fold rotation axis. On cooling below the phase transition temperature, the hydrogen bonds become ordered, resulting in a symmetry reduction of the klassengleiche type of index 2. In the low-temperature phase (P212121, Z ′ = 1 ${Z}^{\prime }=1$ ), the c parameter is doubled with respect to the high-temperature phase. The hydrogen-bonding topology of the high- and low-temperature phases are double-infinite directed and undirected linear graphs, respectively.

scholarly journals Comparison of the crystal structures of the low- and high-temperature forms of bis[4-(dimethylamino)pyridine]dithiocyanatocobalt(II)

2021 ◽  
Vol 77 (11) ◽  
Author(s):  
Christoph Krebs ◽  
Inke Jess ◽  
Christian Näther
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Low Temperature ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Three Dimensional ◽  
Monoclinic Space Group ◽  
Temperature Form ◽  
Dimensional Network ◽  
High Temperature Form

Single crystals of the high-temperature form I of [Co(NCS)2(DMAP)2] (DMAP = 4-dimethylaminopyridine, C7H10N2) were obtained accidentally by the reaction of Co(NCS)2 with DMAP at slightly elevated temperatures under kinetic control. This modification crystallizes in the monoclinic space group P21/m and is isotypic with the corresponding Zn compound. The asymmetric unit consists of one crystallographically independent Co cation and two crystallographically independent thiocyanate anions that are located on a crystallographic mirror plane and one DMAP ligand (general position). In its crystal structure the discrete complexes are linked by C—H...S hydrogen bonds into a three-dimensional network. For comparison, the crystal structure of the known low-temperature form II, which is already thermodynamically stable at room temperature, was redetermined at the same temperature. In this polymorph the complexes are connected by C—H...S and C—H...N hydrogen bonds into a three-dimensional network. At 100 K the density of the high-temperature form I (ρ = 1.457 g cm−3) is lower than that of the low-temperature form II (ρ = 1.462 g cm−3), which is in contrast to the values determined by XRPD at room temperature. Therefore, these two forms represent an exception to the Kitaigorodskii density rule, for which extensive intermolecular hydrogen bonding in form II might be responsible.

Ca(SCN)2 and Ca(SCN)2 · 2 H2O: Crystal Structure, Thermal Behavior and Vibrational Spectroscopy

2002 ◽  
Vol 57 (12) ◽  
pp. 1419-1426 ◽  
Author(s):  
Claudia Wickleder ◽  
Patrick Larsen
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Hydrogen Bonding ◽  
Single Crystals ◽  
Three Dimensional ◽  
Water Molecules ◽  
Dimensional Network ◽  
Thermal Investigations ◽  
Unknown Structure ◽  
Ir And Raman

The dehydration of Ca(SCN)2∙4H2O yields single crystals of Ca(SCN)2 ∙ 2 H2O as well as of Ca(SCN)2. Ca(SCN)2 ∙ 2 H2O crystallizes with a hitherto unknown structure (orthorhombic, Pnma, Z = 4, a = 1280.1(2), b = 790.3(1), c = 726.9(1) pm, Rall = 0.0430). The Ca2+ ions are surrounded by four SCN− ions and four water molecules. The polyhedra are connected to chains along [010] via common oxygen atoms. The SCN− ions connect these chains to a three-dimensional network so that each thiocyanate group is linked to two Ca2+ ions. Hydrogen bonding with sulfur atoms as acceptors is observed. The crystal structure of Ca(SCN)2 (monoclinic, C2/c, Z = 4, a = 961.7(2), b = 642.4(2), c = 787.2(2) pm, Rall = 0.0673) consists of alternating layers of Ca2+ and SCN− ions. The cations are surrounded by four sulfur and four nitrogen atoms in form of a square antiprism. According to 3∞[Ca(SCN)8/4] each SCN− ion connects four Ca2+ ions with each other. Thermal investigations show a phase transition of Ca(SCN)2 ∙ 4 H2O followed by dehydration to Ca(SCN)2 which finally decomposes yielding CaS. IR and Raman measurements have been performed and the resulting frequencies assigned and discussed.

scholarly journals Re-refinement of sodium ammonium sulfate dihydrate at 170 K

IUCrData ◽  
2020 ◽  
Vol 5 (9) ◽  
Author(s):  
Tamira Eckhardt ◽  
Christoph Wagner ◽  
Peter Imming ◽  
Rüdiger W. Seidel
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrogen Atom ◽  
Ammonium Sulfate ◽  
Paraelectric Phase ◽  
Three Dimensional ◽  
Synthetic Analogue ◽  
Acta Cryst ◽  
X Ray ◽  
Dimensional Network

The title compound, sodium ammonium sulfate dihydrate (SASD), NaNH4SO4·2H2O, a synthetic analogue of the mineral lecontite, is a well known ferroelectric. The crystal structure of the paraelectric phase has been re-refined at 170 K on the basis of single-crystal X-ray data, improving the previous study [Arzt & Glazer (1994). Acta Cryst. B50, 425–431] in terms of accuracy regarding hydrogen-atom positions and thus details of the hydrogen bonding. O—H...O and N—H...O hydrogen bonds between the principal building units [Na(OH2)4O2 octahedra, SO4 tetrahedra and ammonium cations] constitute a three-dimensional network structure.

Mössbauer Studies of Fe2+ in Iron Langbeinites and other Crystals with Langbeinite Structure

1998 ◽  
Vol 53 (1-2) ◽  
pp. 27-37 ◽  
Author(s):  
M. Windhaus ◽  
B. D. Mosel ◽  
W. Müller-Warmuth
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
High Temperature ◽  
Low Temperature ◽  
High Spin State ◽  
Cubic Phases ◽  
Debye Temperatures ◽  
Phase Transition Temperatures ◽  
Abrupt Changes ◽  
Temperature Dependences

Abstract 57 Fe Mössbauer spectra have been measured at various temperatures between 4.2 K and 300 K for iron langbeinites A 2 Fe 2^04)3 with A = K, NH 4 , Rb, T1 and magnesium, manganese and cadmium lang-beinites doped with Fe" + . The spectra revealed several contributions whose isomer shifts and quadru-pole splittings have been obtained by fitting program routines. For the high-temperature cubic phases two crystallographically non-equivalent iron sites have been identified, characteristic of Fe2+ in the high-spin state. Abrupt changes of the quadrupole couplings indicated phase transitions; in some cases, the spectra have also revealed several sites for Fe2+ in low temperature phases. From the temperature dependences, phase transition temperatures, crystal field splittings and Debye temperatures have been derived.

Phase coexistence and the magnetic glass-like phase associated with the Morin type spin reorientation phase transition in SmCrO3

RSC Advances ◽  
2016 ◽  
Vol 6 (93) ◽  
pp. 90255-90262 ◽  
Author(s):  
Malvika Tripathi ◽  
R. J. Choudhary ◽  
D. M. Phase
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Low Temperature ◽  
Phase Coexistence ◽  
Spin Reorientation ◽  
Reorientation Process ◽  
Magnetic Glass

SmCrO3 undergoes a discontinuous Morin type spin reorientation process due to discrete flipping of Cr3+ ions from the high temperature Γ4 to low temperature Γ1 configuration.

scholarly journals Bis(nitrilotriacetamide-κ4 N,O,O′,O′′)silver(I) nitrate

IUCrData ◽  
2018 ◽  
Vol 3 (1) ◽  
Author(s):  
Min Ren ◽  
Ming Yue ◽  
Jingwen Ran
Keyword(s):  
Hydrogen Bonding ◽  
Network Structure ◽  
Title Compound ◽  
Three Dimensional ◽  
Hydrogen Bonding Interactions ◽  
Dimensional Network

In the centrosymmetric cation of the title compound, [Ag(C6H12N4O3)2]NO3, the AgI ion, lying on a threefold rotoinversion axis, is coordinated by two N atoms and six O atoms from two nitrilotriacetamide ligands, forming a distorted dodecahedral environment. In the crystal, cations and anions are linked through N—H...O hydrogen-bonding interactions, leading to a three-dimensional network structure.

scholarly journals Crystal structure of trihydrogen bis{[1,1,1-tris(2-oxidoethylaminomethyl)ethane]cobalt(III)} trinitrate

2015 ◽  
Vol 71 (12) ◽  
pp. m275-m276 ◽  
Author(s):  
Waqas Sethi ◽  
Heini V. Johannesen ◽  
Thorbjørn J. Morsing ◽  
Stergios Piligkos ◽  
Høgni Weihe
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Network Structure ◽  
Title Compound ◽  
Rotation Axis ◽  
Three Dimensional ◽  
Rotation Axes ◽  
Dimensional Network ◽  
Nitrate Anions

The title compound, [Co2(L)2]3+·3NO3−[whereL= CH3C(CH2NHCH2CH2OH1/2)3], has been synthesized from the ligand 1,1,1-tris(2-hydroxyethylaminomethyl)ethane. The cobalt(III) dimer has an interesting and uncommon O—H...O hydrogen-bonding motif with the three bridging hydroxy H atoms each being equally disordered over two positions. In the dimeric trication, the octahedrally coordinated CoIIIatoms and the capping C atoms lie on a threefold rotation axis. The N atoms of two crystallographically independent nitrate anions also lie on threefold rotation axes. N—H...O hydrogen bonding between the complex cations and nitrate anions leads to the formation of a three-dimensional network structure. The compound is a racemic conglomerate of crystals containing either D or L molecules. The crystal used for this study is a D crystal.

scholarly journals Crystal structure and hydrogen bonding in the water-stabilized proton-transfer salt brucinium 4-aminophenylarsonate tetrahydrate

2016 ◽  
Vol 72 (5) ◽  
pp. 751-755 ◽  
Author(s):  
Graham Smith ◽  
Urs D. Wermuth
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Network Structure ◽  
Three Dimensional ◽  
Water Molecules ◽  
Arsanilic Acid ◽  
Dimensional Network

In the structure of the brucinium salt of 4-aminophenylarsonic acid (p-arsanilic acid), systematically 2,3-dimethoxy-10-oxostrychnidinium 4-aminophenylarsonate tetrahydrate, (C23H27N2O4)[As(C6H7N)O2(OH)]·4H2O, the brucinium cations form the characteristic undulating and overlapping head-to-tail layered brucine substructures packed along [010]. The arsanilate anions and the water molecules of solvation are accommodated between the layers and are linked to them through a primary cation N—H...O(anion) hydrogen bond, as well as through water O—H...O hydrogen bonds to brucinium and arsanilate ions as well as bridging water O-atom acceptors, giving an overall three-dimensional network structure.

Chlorido(dimethyl 2,2′-bipyridine-4,4′-dicarboxylate-κ2N,N′)(η5-pentamethylcyclopentadienyl)rhodium(III) chloride 1-hydroxypyrrolidine-2,5-dione disolvate

2013 ◽  
Vol 69 (6) ◽  
pp. 584-587
Author(s):  
Dharmalingam Sivanesan ◽  
Hyung Min Kim ◽  
Yoon Sungho
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Substitution Reaction ◽  
Three Dimensional ◽  
Title Complex ◽  
Rhodium Complex ◽  
Synthetic Route ◽  
Dimensional Network ◽  
Weak Hydrogen Bonds ◽  
Solvent Molecules

The title complex, [Rh(C10H15)Cl(C14H12N2O4)]Cl·2C4H5NO3, has been synthesized by a substitution reaction of the precursor [bis(2,5-dioxopyrrolidin-1-yl) 2,2′-bipyridine-4,4′-dicarboxylate]chlorido(pentamethylcyclopentadienyl)rhodium(III) chloride with NaOCH3. The RhIIIcation is located in an RhC5N2Cl eight-coordinated environment. In the crystal, 1-hydroxypyrrolidine-2,5-dione (NHS) solvent molecules form strong hydrogen bonds with the Cl−counter-anions in the lattice and weak hydrogen bonds with the pentamethylcyclopentadienyl (Cp*) ligands. Hydrogen bonding between the Cp* ligands, the NHS solvent molecules and the Cl−counter-anions form links in a V-shaped chain of RhIIIcomplex cations along thecaxis. Weak hydrogen bonds between the dimethyl 2,2′-bipyridine-4,4′-dicarboxylate ligands and the Cl−counter-anions connect the components into a supramolecular three-dimensional network. The synthetic route to the dimethyl 2,2′-bipyridine-4,4′-dicarboxylate-containing rhodium complex from the [bis(2,5-dioxopyrrolidin-1-yl) 2,2′-bipyridine-4,4′-dicarboxylate]rhodium(III) precursor may be applied to link Rh catalysts to the surface of electrodes.

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