Synthese, Struktur und Eigenschaften der Hexabromotellur(IV)- und Tridekabromotritellur(IV)säure-Hydrate. Kristallstrukturen der Oxonium-Salze [H9O4]2[TeBr6] und [H9O4][Te3Br13] / Synthesis, Structure and Properties of Hexabromotellurous and Tridecabromotritellurous Acid Hydrates. Crystal Structures of the Oxonium Salts [H9O4]2[TeBr6] and [H9O4][Te3Br13]

1991 ◽  
Vol 46 (7) ◽  
pp. 919-930 ◽  
Author(s):  
Bernt Krebs ◽  
Stefan Bonmann ◽  
Klemens Erpenstein
Keyword(s):  
Concentration Ratio ◽  
Stoichiometric Composition ◽  
Structural Formula ◽  
Structure And Properties ◽  
Space Group ◽  
X Ray ◽  
Edge Sharing Octahedra ◽  
Hydrogen Bond System ◽  
Bond System ◽  
The Mean

From solutions of TeBr4 in concentrated aqueous HBr red needles of the crystalline hexabromotellurous acid with the stoichiometric composition H2TeBr6 · 8H2O (1) were isolated (space group P21/n, a = 7.662(5), b = 9.796(6), c = 11.987(8) Å, β = 91.35(4)° at 259 Κ). If the HBr:TeBr4 concentration ratio in the system TeBr4/HBr/H2O was kept low, a novel acid with formal composition HTe3Br13 ·4 H2O (2) could be prepared (space group Cm, a = 13.501(5), b = 15.453(6), c = 9.153(3) Å, β = 138.11(2)° at 140 Κ). The X-ray structural analysis of 1 shows the acid to contain, besides regular octahedral [TeBr6]2- ions (Te-Br: 2.671(4)-2.716(4) Å), [Η9Ο4]+ hydroxonium ions (O ··· O: 2.48(3)-2.62(3) Å). The [H9O4]+ units are linked through a hydrogen bond system (O ··· O: 2.80(3)-2.97(4) Å) to form a three-dimen-sional network. The formula has to be written as [H9O4]2[TeBr6]. 2 is the first acid in this class with a trinuclear anion. Its structural formula is [H9O4][Te3Br13]. As a fragment of the Te4Br,6 cube the anion consists of three edge-sharing octahedra with a central triply bridging Br. The mean bond distances are 2.515 Å for terminal Te-Br, 2.944 Å for Te-μ2Br and 3.077 Å for Te—μ3Br. The Ο···Ο distances in the isolated [H9O4]+ hydroxonium ions are 2.45(3)-2.57(2) A. Raman spectra of both acids are reported.

Bromoselenate(II): Darstellung, Struktur und Eigenschaften von [P(C6H5)4]2SeBr4 und [P(C6H5)4]2Se2Br6 / Bromoselenates(II): Preparation, Structure and Properties of [P(C6H5)4]2SeBr4 and [P(C6H5)4]2Se2Br6

1984 ◽  
Vol 39 (12) ◽  
pp. 1633-1641 ◽  
Author(s):  
Bernt Krebs ◽  
Andreas Schäffer ◽  
Siegfried Pohl
Keyword(s):  
Bond Length ◽  
Vibrational Spectra ◽  
Acetonitrile Solution ◽  
The Novel ◽  
Structure And Properties ◽  
Subsequent Reaction ◽  
Space Group ◽  
X Ray ◽  
Square Planar ◽  
The Mean

The novel anion SeBr42- was prepared by dissociation of SeOBr2 with formation of SeBr2 and subsequent reaction with bromide in acetonitrile solution; it was isolated as the crystalline tetraphenylphosphonium salt. The X-ray structure analysis of [P(C6H 5)4]2SeBr4 (space group P 1̄ , a = 14.190(3), b = 15.125(3), c = 10.383(2) Å , α = 92.69(2), β = 100.89(2), γ = 92.04(2)° Å , V = 2182.2 Å3) shows the structure to contain monomeric SeBr42- anions with a square planar coordination of Se(II). The mean Se -Br bond length in the anion is 2.598 Å .[P(C6H5)4]2Se2Br6 was obtained from the reaction of SeBr4 (which is in equilibrium with SeBr2, Se2Br2, and Br2, in solution) and bromide in acetonitrile. It crystallizes in the space group P 1̄, with a = 1 0 . 9 3 3 ( 4 ) , = 11.154(4), c = 10.344(4) Å , α = 79.26(3), β = 72.63(3), y = 81.35(3)°, γ = 1176.7 Å3 (at -120 °C), and contains a novel type of centrosymmetric Se2Br62- ions with square planar Se-coordination. The mean terminal and bridging Se -Br bond lengths are 2.442 and 2.799 Å , resp. Vibrational spectra are reported and discussed.

Solvatisierte HalogenochaLkogen(IV)säuren, I Darstellung und Struktur des Hexabromoselen(IV)säure-Hydrats (H5O2)2SeBr6 · 4H2O / Solvated Halogeno-Chalcogen(IV) Acids, I Preparation and Structure of the Hexabromoselenium(IV) Acid Hydrate (H5O2)2SeBr6 · 4H2O

1979 ◽  
Vol 34 (12) ◽  
pp. 1666-1670 ◽  
Author(s):  
Bernt Krebs ◽  
Michael Hein
Keyword(s):  
Hydrogen Bond ◽  
Single Crystal ◽  
Low Temperatures ◽  
Stoichiometric Composition ◽  
Crystalline Compound ◽  
X Ray ◽  
Hydronium Ions ◽  
Hydrogen Bond System ◽  
Bond System ◽  
Acid Hydrate

Hexabromoselenium(IV) acid with the stoichiometric composition H2SeBr6 · 8 H2O is prepared from solutions of SeBr4 in concentrated aqueous HBr. If separated from the solution, the crystalline compound is stable only at low temperatures.A single crystal X-ray structure analysis at -100 °C (monoclinic, C2/m, a = 1039.4(5), b = 1028.8(4), c = 836.6(3) pm, β = 104.11(4)°) shows the acid to contain, besides regular octahedral SeBr62- ions (Se-Br: 255.3(2)-257.9(2) pm), H5O2+ hydronium ions (O···O: 255(2) pm). The remaining H2O molecules are involved in a hydrogen bond system with O···O: 264(2)-275(2) pm and O···Br: 342(1), 351(1) pm. The formula has to be written as (H5O2)2SeBr6 · 4 H2O.

Thio-hydroxoanionen des Germaniums: Darstellung, Struktur und Eigenschaften von Na2GeS2(OH)2 · 5 H2O / Thio-hydroxo Anions of Germanium: Preparation, Structure and Properties of Na2GeS2(OH)2 · 5 H2O

1981 ◽  
Vol 36 (11) ◽  
pp. 1400-1406 ◽  
Author(s):  
Bernt Krebs ◽  
Hans-Joachim Wallstab
Keyword(s):  
Hydrogen Bond ◽  
Aqueous Solutions ◽  
Vibrational Spectra ◽  
Sodium Sulfide ◽  
Structure And Properties ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Hydrogen Bond System ◽  
Bond System ◽  
Stretching Vibrations

Abstract Pure thio-hydroxo-germanates can be prepared from aqueous solutions by reactions of stoichiometric amounts of either sodium sulfide and GeO2, or NaOH and GeS2. The preparation of colourless crystalline Na2GeS2(OH)2 · 5 H2O is reported. The compound is characterized by a single-crystal X-ray structure analysis. It is orthorhombic, space group Pbcn, with a = 10.752(2), b= 13.787(2), c = 14.150(2) Å. The structure contains novel monomeric GeS2(OH)22- anions with Ge-S bond distances of 2.150(1) and 2.145(1) Å and with Ge-O lengths of 1.809(3) and 1.815(3) Å. An extensive S ··· HO-and O -HO-hydrogen bond system connects the anions with the octahedrally coordinated Na+ ions. The vibrational spectra are reported. The symmetric GeS2 andGeO2 stretching vibrations in the anion are observed at 415 and 618 cm-1.

Pyridine 1:1 adducts of urea (Z′ = 1) and thiourea (Z′ = 8)

2018 ◽  
Vol 74 (4) ◽  
pp. 406-410 ◽  
Author(s):  
Mark Strey ◽  
Peter G. Jones
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Layer Structure ◽  
Urea Adduct ◽  
Standard Type ◽  
Space Group ◽  
Hydrogen Bond System ◽  
Bond System ◽  
Bifurcated Hydrogen Bond ◽  
Urea Adducts

During our studies of urea and thiourea adducts, we noticed that no adducts with unsubstituted pyridine had been structurally investigated. The 1:1 adduct of pyridine and urea, C5H5N·CH4N2O, crystallizes in the P21/c space group with Z = 4. The structure is of a standard type for urea adducts, whereby the urea molecules form a ribbon, parallel to the a axis, consisting of linked R 2 2(8) rings, and the pyridine molecules are attached to the periphery of the ribbon by bifurcated (N—H...)2N hydrogen bonds. The 1:1 adduct of pyridine and thiourea, C5H5N·CH4N2S, crystallizes in the P21/n space group, with Z = 32 (Z′ = 8). The structure displays similar ribbons to those of the urea adduct. There are two independent ribbons parallel to the b axis at z ≃ 0 and 1 \over 2, and three at z ≃ 1 \over 4 and 3 \over 4; the latter are crosslinked to form a layer structure by additional long N—H...S interactions, which each formally replace one branch of a bifurcated hydrogen-bond system.

Inclusion compounds of plant growth regulators in cyclodextrins. V. 4-Chlorophenoxyacetic acid encapsulated in β-cyclodextrin and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin

2005 ◽  
Vol 61 (2) ◽  
pp. 207-217 ◽  
Author(s):  
Frantzeska Tsorteki ◽  
Kostas Bethanis ◽  
Nikos Pinotsis ◽  
Petros Giastas ◽  
Dimitris Mentzafos
Keyword(s):  
Guest Molecule ◽  
Crystal Packing ◽  
Host Molecule ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
Space Group ◽  
X Ray ◽  
Dimeric Complexes ◽  
The Mean ◽  
Chlorophenoxyacetic Acid

The crystal structures of 4-chlorophenoxyacetic acid (4CPA) included in β-cyclodextrin (β-CD) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TMβCD) have been studied by X-ray diffraction. The 4CPA/β-CD complex crystallizes as a head-to-head dimer in the space group C2 in the Tetrad packing mode. The packing modes of some β-CD dimeric complexes, having unique stackings, are also discussed. The 4CPA/TMβCD inclusion complex crystallizes in the space group P21 and its asymmetric unit contains two crystallographically independent complexes, complex A and complex B, exhibiting different conformations. The host molecule of complex A is significantly distorted, as a glucosidic residue rotated about the O4′—C1 and C4—O4 bonds forms an aperture where the guest molecule is accommodated. The phenyl moiety of the guest molecule of complex B is nearly perpendicular to the mean plane of the O4n atoms. The conformations of the guest molecules of the two complexes are similar. The crystal packing consists of antiparallel columns as in the majority of the TMβCD complexes published so far.

scholarly journals The Ti-Fe-P system: phase equilibria and crystal structure of phases

2013 ◽  
Vol 11 (9) ◽  
pp. 1518-1526 ◽  
Author(s):  
Oksana Toma ◽  
Mariya Dzevenko ◽  
Anton Oliynyk ◽  
Yaroslava Lomnytska
Keyword(s):  
Crystal Structure ◽  
Phase Equilibria ◽  
Stoichiometric Composition ◽  
P System ◽  
Single Crystal Diffraction ◽  
Space Group ◽  
X Ray ◽  
Type Space ◽  
Binary Compounds ◽  
System Phase

AbstractAbstract Phase equilibria was investigated in the Ti-Fe-P system at T = 1070 K in the region 0–67 at.% of P, employing X-ray powder diffraction. The two ternary compounds, namely Ti0.5–0.8Fe1.5−1.2P (Co2Si-type; space group Pnma; a = 0.5964(2)–0.6011(3), b = 0.3575(3)–0.3600(1), c = 0.6828(2)–0.6882(2) nm) and Ti0.85−1.25Fe1.15−0.75P (ZrNiAl-type; space group P-62m; a = 0.6071(4)–0.6117(1), c = 0.3510(9)–0.3506(1) nm) exist in the Ti-Fe-P system at this temperature. The crystal structure of the Ti0.85–1.25Fe1.15−0.75P compound was additionally determined by X-ray single crystal diffraction on the phase with stoichiometric composition. The substitutions of Ti by Fe were observed for Ti5P3.16, Ti3P and TiP phases, and Fe for Ti in the case of Fe3P, Fe2P binary compounds. Graphical abstract

Electron density, disorder and polymorphism: high-resolution diffraction studies of the highly polymorphic neuralgic drug carbamazepine

2016 ◽  
Vol 72 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Ioana Sovago ◽  
Matthias J. Gutmann ◽  
Hans Martin Senn ◽  
Lynne H. Thomas ◽  
Chick C. Wilson ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Diffraction Data ◽  
Structural Formula ◽  
Orthorhombic Crystal ◽  
Monoclinic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Monoclinic Crystal Structure

Analysis of neutron and high-resolution X-ray diffraction data on form (III) of carbamazepine at 100 K using the atoms in molecules (AIM) topological approach afforded excellent agreement between the experimental results and theoretical densities from the optimized gas-phase structure and from multipole modelling of static theoretical structure factors. The charge density analysis provides experimental confirmation of the partially localized π-bonding suggested by the conventional structural formula, but the evidence for any significant C—N π bonding is not strong. Hirshfeld atom refinement (HAR) gives H atom positional and anisotropic displacement parameters that agree very well with the neutron parameters. X-ray and neutron diffraction data on the dihydrate of carbemazepine strongly indicate a disordered orthorhombic crystal structure in the space groupCmca, rather than a monoclinic crystal structure in space groupP21/c. This disorder in the dihydrate structure has implications for both experimental and theoretical studies of polymorphism.

scholarly journals Refinement of the crystal structure of a synthetic non-stoichiometric Rb-feldspar

2001 ◽  
Vol 65 (4) ◽  
pp. 523-531 ◽  
Author(s):  
A. Kyono ◽  
M. Kimata
Keyword(s):  
Crystal Structure ◽  
Ir Spectra ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Deviation From Stoichiometry ◽  
The Mean ◽  
Unit Formula ◽  
Natural And Synthetic

AbstractThe crystal structure of hydrothermally synthesized Rb-feldspar (monoclinic, space group C2/m, a= 8.839(2)Å, b= 13.035(2)Å, c= 7.175(2)Å, β = 116.11(1)8, V= 742.3(3)Å3, Z= 4) has been refined to a final R of 0.0574 for 692 independent X-ray reflections. Microprobe analyses of the Rb-feldspar suggest deviation from stoichiometry, with excess Si and Al, resulting in a unit formula of Rb0.811□0.127Al1.059Si3.003O8. Infrared (IR) spectra indicate the structural occupancy of large H2O content, which implies that the □Si4O8 substitution favours the structural incorporation of the H2O molecule at the M-site. The mean T–O distances are 1.632 Å for T1 and 1.645 Å for T2, revealing highly disordered (Al,Si) distribution with Al/Si = 0.245/0.755 (T1 site) and 0.255/0.745 (T2 site).There are two geochemical implications from this refinement: (1) identification of both rubicline triclinic with (Al,Si) ordered distribution and synthetic monoclinic RbAlSi3O8 with (Al,Si) disordered distribution implies that Rb cannot be one of factors disrupting the (Al,Si) ordered and disordered distributions in feldspars; and (2) natural and synthetic feldspars capable of accommodating the large cations tend to incorporate □Si4O8, excess Al and H2O components in their crystal structures.

Monomere und dimere Oxotrihalogenoselenate(IV): Darstellung, Struktur und Eigenschaften von [As(C6H5)4]SeOCl3 und [N(C2H5)4]SeOCl3 / Monomerie and Dimeric Oxotrihalogenoselenates(IV): Preparation, Structure and Properties of [As(C6H5)4]SeOCl3 and [N(C2H5)4]SeOCl3

1983 ◽  
Vol 38 (1) ◽  
pp. 20-29 ◽  
Author(s):  
Bernt Krebs ◽  
Marita Hucke ◽  
Michael Hein ◽  
Andreas Schäffer
Keyword(s):  
Polymer Chains ◽  
Monoclinic Space Group ◽  
Structure And Properties ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Centrosymmetric Dimers

Abstract The monomeric SeOCl3- ion, which can be prepared as the tetraphenylarsonium salt from SeOCl2 and As(C6H5)4Cl, was structurally characterized by a low-temperature single crystal X-ray diffraction analysis. [As(C6H5)4]SeOCl3 is monoclinic, space group P21/c, with a = 9,332(3), b = 13,761(4), c = 18,985(6) Å, β = 110,97(3)° (at -135 °C), Z = 4; it contains a novel type of ψ-trigonal bipyramidal oxotrichloroselenate(IV) anion which is not associated to dimers or polymer chains as in known structures. The equatorial positions are occupied by doubly bonded oxygen (Se-O 1,601(3) Å) and by one Cl(Se-Cl 2,234(1) Å), the axial Se-Cl bonds (2,430(1) and 2,475(1) Å) being significantly longer. [N(C2H5)4]SeOCl3, which was obtained as crystals by oxidation of trichloroselenate(II), is triclinic, space group P1̄, with a = 10,607(3), b = 8,950(2), c = 8,862(2) Å, α = 119,79(2)°, β = 101,07(2)°, γ = 96,28(2)°, Z = 2. The X-ray structure analysis shows the anions to be present as centrosymmetric dimers Se2O2Cl62- like in the [P(C6H5)4]+ salt, with two tetragonal SeOCl4 pyramids linked through a Cl···Cl edge and the lone pairs trans to the axial Se-O bonds (1,589(4) Å). Se-Cl bond lengths are 2.270(1) and 2,351(2) Å (terminal); 2,698(1) and 2,920(1) Å (bridging). The results show that the nature of the reaction products of the Lewis acid SeOCl2 with halogenides as bases changes very sensitively with small variations in cations and environment. The vibrational spectra are discussed.

Crystallographic data about hydrated and anhydrous lithium monoborates

1997 ◽  
Vol 12 (3) ◽  
pp. 155-159 ◽  
Author(s):  
E. Bétourné ◽  
M. Touboul
Keyword(s):  
Diffraction Study ◽  
Water Content ◽  
Powder Diffraction ◽  
Structural Formula ◽  
Crystallographic Data ◽  
The Other ◽  
Crystal Data ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters

The anhydrous and hydrated lithium monoborates have been studied. The most hydrated phase is LiBO2·8H2O; its structural formula in the P3 space group is Li(H2O)4B(OH)4·2H2O. Refinement of the cell parameters yielded the following results: a=6.5483(5) Å, c=6.1692(7) Å with F(30)=64(0.015, 32), Z=1, and Dx=1.402 g/cm3. This phase gives LiB(OH)4 by spontaneous dehydration. An X-ray powder diffraction study of LiB(OH)4 as a function of temperature indicated three poorly crystallized hydrates. Two of these hydrates have the formula LiBO2·0.3H2O; the other, LiBO2·xH2O, has an undetermined water content. Crystal data for α-LiBO2 have been obtained: a=5.8473(10) Å, b=4.3513(6) Å, c=6.4557(10) Å, β=115.08(1)°, F(27)=58.5(0.001, 41); space group P21/c, Z=4, and Dx=2.18 g/cm3. β-LiBO2 does not exist but corresponds to the α-LiBO2 form observed at 600 °C. Numerous other LiBO2 forms reported recently have not been found.

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