Extrem asymmetrisch gebundene Wassermoleküle-Kristallstrukturen von Sr(OH)Cl · 4 H2O, Sr(OH)Br · 4 H2O und Ba(OH)I·4 H2O / Extremely Asymmetrically Bound Water Molecules-Crystal Structures of Sr(OH)Cl · 4 H2O, Sr(OH)Br · 4 H2O, and Ba(OH)I·4 H2O

1991 ◽  
Vol 46 (10) ◽  
pp. 1279-1286 ◽  
Author(s):  
Thomas Kellersohn ◽  
Konrad Beckenkamp ◽  
Heinz Dieter Lutz
Keyword(s):  
Crystal Structures ◽  
Bound Water ◽  
Structure Type ◽  
Water Molecules ◽  
Halide Ions ◽  
Weak Hydrogen Bond ◽  
Scanning Calorimetry ◽  
Unknown Structure ◽  
Stretching Vibrations ◽  
Strong Distortion

The crystal structures of isotypic Sr(OH)Cl ·4 H2O, Sr(OH)Br·4 H2O, and Ba(OH)I·4 H2O are reported. The title compounds crystallize in a hitherto unknown structure type, space group PĪ, Z = 2. The final R values obtained are 0.0261, 0.069, and 0.062, respectively. The coordination of the metal ions is monocapped square antiprismatic with 7 H2O, 1 OH- and 1 halide ion. The halide ions separate metal/water/hydroxide layers. Each of the four crystallographically different water molecules serves as donor for one very strong and one very weak hydrogen bond and, hence, is extremely asymmetrically bound. Owing to this strong distortion, the largest one known so far, the OH stretching vibrations of the H2O molecules are intramolecularly decoupled as shown from vibrational spectra. The enthalpies of dehydration obtained from differential scanning calorimetry are reported.

scholarly journals Zur Kenntnis der Hydroxidhalogenide des Bariums. Kristallstruktur und Schwingungsspektren von Ba[O(H,D)]X · 2 (H,D)2O (X = Cl, Br) / Barium Hydroxide Halides. Crystal Structure and Vibrational Spectra of Ba[O(H,D)]X · 2 (H,D)2O (X = Cl, Br)

1989 ◽  
Vol 44 (8) ◽  
pp. 928-935 ◽  
Author(s):  
Heinz Dieter Lutz ◽  
Thomas Kellersohn ◽  
Konrad Beckenkamp
Keyword(s):  
Structure Type ◽  
Water Molecules ◽  
Halide Ions ◽  
Barium Ions ◽  
X Ray ◽  
Isotopic Shifts ◽  
Unknown Structure ◽  
Dta And Tg ◽  
Ray Methods ◽  
Ir And Raman

The quaternary systems Ba(OH)2—BaCl2—H2O and Ba(OH)2—BaBr2—H2O were studied with the help of X-ray and neutron diffraction as well as IR, Raman, DTA, and TG methods. The following compounds have been established or confirmed: Ba(OH)Cl · nH2O (n = 0, 1/2, 2) and Ba(OH)Br · H2O (n = 0, 1/2, 2). The crystal structures (of hitherto unknown structure type) of Ba(OH)Cl- 2 H2O and Ba(OD)Cl · 2 D2O were determined by single crystal X-ray methods and neutron powder diffraction (space group P4/nmm, Z = 2, 621 unique reflections, R = 8.8 and 1.9%, respectively). Whereas the hydroxide ion in this layer structured compound is non-hydrogen bonded, i. e. no Η-bond donor group, nor it is bound to the Ba2+ ions, the water molecules are involved in strong Η-bonds to adjacent OH- ions. The coordination of the barium ions is monocapped tetragonal antiprismatic (4 H2O and 5 halide ions). The IR and Raman spectra of Ba(OH)X · 2 H2O (X = Cl, Br) are assigned and discussed in terms of hydrogen bonding, isotopic shifts, and intermolecular coupling of the bands observed. The stretching modes of the OH- ions (3672 and 3667 cm-1, 95 K) are shifted to higher wavenumbers by about 100 cm-1 as compared with those of free OH- ions.

The infra-red spectra of talc, saponite, and hectorite

1958 ◽  
Vol 31 (241) ◽  
pp. 829-845 ◽  
Author(s):  
V. C. Farmer
Keyword(s):  
Hydrogen Bond ◽  
Dipole Moment ◽  
Absorption Spectra ◽  
Water Molecules ◽  
Weak Hydrogen Bond ◽  
Interlayer Water ◽  
Spectral Changes ◽  
Infra Red ◽  
Theoretical Predictions ◽  
Stretching Vibrations

SummaryThe absorption spectra of talc, saponite, and hectorite between 4000 and 400 cm. −1 are closely related, although the bands of the smectites are more diffuse as a result of isomorphous substitutions in the tale structure. Using oriented specimens, vibrations in which the change of dipole moment is perpendicular to the sheets of the minerals are identified, and the results compared with theoretical predictions. Three bands arising from the stretching vibrations of interlayer water molecules in the smectites are distinguished, one of which corresponds to a very weak hydrogen bond. Spectral changes arising from vigorous grinding are discussed.

scholarly journals (NH4)Mg(HSO4)(SO4)(H2O)2 and NaSc(CrO4)2(H2O)2, two crystal structures comprising kröhnkite-type chains, and the temperature-induced phase transition (NH4)Mg(HSO4)(SO4)(H2O)2\rightleftharpoons (NH4)MgH(SO4)2(H2O)2

2021 ◽  
Vol 77 (3) ◽  
pp. 144-151
Author(s):  
Matthias Weil ◽  
Uwe Kolitsch
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Room Temperature ◽  
Classification Scheme ◽  
Three Dimensional ◽  
Structure Type ◽  
Group Symmetry ◽  
Water Molecules

The crystal structure of the mineral kröhnkite, Na2Cu(SO4)2(H2O)2, contains infinite chains composed of [CuO4(OH2)2] octahedra corner-linked with SO4 tetrahedra. Such or similar tetrahedral–octahedral `kröhnkite-type' chains are present in the crystal structures of numerous compounds with the composition AnM(XO4)2(H2O)2. The title compounds, (NH4)Mg(HSO4)(SO4)(H2O)2, ammonium magnesium hydrogen sulfate sulfate dihydrate, and NaSc(CrO4)2(H2O)2, sodium scandium bis(chromate) dihydrate, are members of the large family with such kröhnkite-type chains. At 100 K, (NH4)Mg(HSO4)(SO4)(H2O)2 has an unprecedented triclinic crystal structure and contains [MgO4(OH2)2] octahedra linked by SO3(OH) and SO4 tetrahedra into chains extending parallel to [\overline{1}10]. Adjacent chains are linked by very strong hydrogen bonds between SO3(OH) and SO4 tetrahedra into layers parallel to (111). Ammonium cations and water molecules connect adjacent layers through hydrogen-bonding interactions of medium-to-weak strength into a three-dimensional network. (NH4)Mg(HSO4)(SO4)(H2O)2 shows a reversible phase transition and crystallizes at room temperature in structure type E in the classification scheme for structures with kröhnkite-type chains, with half of the unit-cell volume for the resulting triclinic cell, and with disordered H atoms of the ammonium tetrahedron and the H atom between two symmetry-related sulfate groups. IR spectroscopic room-temperature data for the latter phase are provided. Monoclinic NaSc(CrO4)2(H2O)2 adopts structure type F1 in the classification scheme for structures with kröhnkite-type chains. Here, [ScO4(OH2)2] octahedra (point group symmetry \overline{1}) are linked by CrO4 tetrahedra into chains parallel to [010]. The Na+ cations (site symmetry 2) have a [6 + 2] coordination and connect adjacent chains into a three-dimensional framework that is consolidated by medium–strong hydrogen bonds involving the water molecules. Quantitative structural comparisons are made between NaSc(CrO4)2(H2O)2 and its isotypic NaM(CrO4)2(H2O)2 (M = Al and Fe) analogues.

Synthese und Kristallstruktur von Dibariumzink-bis(cyclotriborat) Ba2Zn(B3O6)2/Synthesis and Crystal Structure of Di-barium Zinc Bis-cyclotriborate Ba2Zn(B3O6)2

1996 ◽  
Vol 51 (3) ◽  
pp. 309-312 ◽  
Author(s):  
Silke Busche ◽  
Karsten Bluhm
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Single Crystals ◽  
Crystal Structures ◽  
Structure Type ◽  
Lattice Parameters ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Unknown Structure

Abstract Single crystals of the new compound Ba2Zn(B3O6)2 were obtained by using a B2O3 flux technique. They crystallize in an as yet unknown structure type. X-ray investigations led to space group Ci1-P1̄ (Nr.2) with lattice parameters a = 715.5(2), b = 720.5(2), c = 1178.9(4), a = 78.96(2)°, β = 85.45(2)°, γ = 60.12(1)°, Z = 2. The structure is characterized by iso­lated (B3O6)3--rings and contains two ninefold coordinated Ba-sites. Zn2+ is tetrahedrally coordinated by oxygen. The relation to the crystal structures of high-temperature BaB2O4 and Ba2Ca(B3O6)2 is discussed.

scholarly journals Structural and Thermal Investigations of L-CuC4H4O6·3H2O and DL-CuC4H4O6·2H2O Single Crystals

2021 ◽  
Vol 13 (1) ◽  
pp. 38
Author(s):  
Takanori Fukami ◽  
Shuta Tahara
Keyword(s):  
Room Temperature ◽  
Structural Parameters ◽  
Bound Water ◽  
Silica Gels ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Weight Losses ◽  
Thermal Investigations ◽  
Group Symmetries

Copper(II) L-tartrate trihydrate, L-CuC4H4O6·3H2O, and copper(II) DL-tartrate dihydrate, DL-CuC4H4O6·2H2O, crystals were grown at room temperature by the gel method using silica gels as the growth medium. Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on both crystals. The space group symmetries (monoclinic P21 and P21/c) and structural parameters of the crystals were determined at room temperature and at 114 K. Both structures consisted of slightly distorted CuO6 octahedra, C4H4O6 and H2O molecules, C4H4O6–Cu–C4H4O6 chains linked by Cu–O bonds, and O–H–O hydrogen-bonding frameworks between adjacent molecules. Weight losses due to thermal decomposition of the crystals were found to occur in the temperature range of 300–1250 K. We inferred that the weight losses were caused by the evaporation of bound water molecules and the evolution of H2CO, CO, and O2 gases from C4H4O6 molecules, and that the residual reddish-brown substance left in the vessels after decomposition was copper(I) oxide (Cu2O).

scholarly journals Structured Waters Mediate Small Molecule Binding to G-Quadruplex Nucleic Acids

2021 ◽  
Vol 15 (1) ◽  
pp. 7
Author(s):  
Stephen Neidle
Keyword(s):  
Crystal Structures ◽  
Small Molecule ◽  
Drug Targets ◽  
Bound Water ◽  
Water Molecules ◽  
Telomeric Dna ◽  
Naphthalene Diimide ◽  
In Silico Studies ◽  
G Quadruplex

The role of G-quadruplexes in human cancers is increasingly well-defined. Accordingly, G-quadruplexes can be suitable drug targets and many small molecules have been identified to date as G-quadruplex binders, some using computer-based design methods and co-crystal structures. The role of bound water molecules in the crystal structures of G-quadruplex-small molecule complexes has been analyzed in this study, focusing on the water arrangements in several G-quadruplex ligand complexes. One is the complex between the tetrasubstituted naphthalene diimide compound MM41 and a human intramolecular telomeric DNA G-quadruplex, and the others are in substituted acridine bimolecular G-quadruplex complexes. Bridging water molecules form most of the hydrogen-bond contacts between ligands and DNA in the parallel G-quadruplex structures examined here. Clusters of structured water molecules play essential roles in mediating between ligand side chain groups/chromophore core and G-quadruplex. These clusters tend to be conserved between complex and native G-quadruplex structures, suggesting that they more generally serve as platforms for ligand binding, and should be taken into account in docking and in silico studies.

scholarly journals Structural Refinements and Thermal Properties of L(+)-Tartaric, D(–)-Tartaric, and Monohydrate Racemic Tartaric Acid

2016 ◽  
Vol 8 (2) ◽  
pp. 9 ◽  
Author(s):  
Takanori Fukami ◽  
Shuta Tahara ◽  
Chitoshi Yasuda ◽  
Keiko Nakasone
Keyword(s):  
Tartaric Acid ◽  
Room Temperature ◽  
Bound Water ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Weight Losses ◽  
Minimum Potential

<p>Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on single crystals of L(+)-tartaric, D(–)-tartaric, and monohydrate racemic (MDL-) tartaric acid. The exact crystal structures of the three acids, including the positions of all hydrogen atoms, were determined at room temperature. It was pointed out that one of O–H–O hydrogen bonds in MDL-tartaric acid has an asymmetric double-minimum potential well along the coordinate of proton motion. The weight losses due to thermal decomposition of L- and D-tartaric acid were observed to occur at 443.0 and 443.2 K, respectively, and at 306.1 and 480.6 K for MDL-tartaric acid. The weight losses for L- and D-tartaric acid during decomposition were probably caused by the evolution of 3H<sub>2</sub>O and 3CO gases. By considering proton transfer between two possible sites in the hydrogen bond, we concluded that the weight losses at 306.1 and 480.6 K for MDL-tartaric acid were caused by the evaporation of half the bound water molecules in the sample, and by the evaporation of the remaining water molecules and the evolution of 3H<sub>2</sub>O and 3CO gases, respectively.</p>

CuTb2[B8O16]: Das erste „Metaborat“ mit einem 1∞[B8O16]8--Anion / CuTb2[B8O16]: The First “Metaborate” with a 1∞[B8O16]8- Anion

1995 ◽  
Vol 50 (5) ◽  
pp. 757-761 ◽  
Author(s):  
Jan Schaefer ◽  
Karsten Bluhm
Keyword(s):  
Single Crystals ◽  
Crystal Structures ◽  
Structure Type ◽  
Lattice Parameters ◽  
Space Group ◽  
X Ray ◽  
Bluish Green ◽  
Unknown Structure

Abstract Pale bluish-green single crystals of the new compound CuTb2[B8O16] have been obtained by a B2O3 flux technique. They crystallize in an unknown structure type. X-ray investigations on single crystals led to the space group C52h-P21/c (Nr. 14) with lattice parameters a = 1024.6(1); b = 834.93(6); c = 622.87(6) pm , β = 90.45(2)°; Z = 2. The structure contains 1∞[B8O16]8- chains isolated from each other, which include tri- and tetracoordinated boron. The chains consist of alternating twelve- and eight-membered rings of boron and oxygen connected by BO4 units. Tb3+ is octacoordinated and Cu2+ is hexacoordinated in elongated octahedra by oxygen. The relation to the crystal structures of Tb[B3O6] and CuTb[B5O10] is pointed out.

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