TheZ′ = 12 superstructure of Λ-cobalt(III) sepulchrate trinitrate governed by C—H...O hydrogen bonds

Λ-Cobalt(III) sepulchrate trinitrate crystallizes inP6322 withZ= 2 (Z′ = 1/6) at room temperature. Slabs perpendicular to the hexagonal axis comprise molecules Co(sepulchrate) alternating with nitrate groupsAandB. Coordinated by six sepulchrate molecules, highly disordered nitrate groupsCare accommodated between the slabs. Here we report the fully ordered, low-temperature crystal structure of Co(sep)(NO3)3. It is found to be a high-Z′ structure withZ′ = 12 of the 12-fold 6a_{h}\times\sqrt{3}b_{h}\times c_{h} superstructure with monoclinic symmetryP21(cunique). Correlations between structural parameters are effectively removed by refinements within the superspace approach. Superstructure formation is governed by a densification of the packing in conjunction with ordering of nitrate groupC, the latter assuming different orientations for each of theZ′ = 12 independent copies in the superstructure. The Co(sep) moiety exhibits small structural variations over its 12 independent copies, while orientations of nitrate groupsAandBvary less than the orientations of the nitrate groupCdo. Molecular packing in the superstructure is found to be determined by short C—H...H—C contacts, with H...H distances of 2.2–2.3 Å, and by short C—H...O contacts, with H...O distances down to 2.2 Å. These contacts presumably represent weak C—H...O hydrogen bonds, but in any case they prevent further densification of the structure and strengthening of weak N—H...O hydrogen bonds with observed H...O distances of 2.4–2.6 Å.

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Low-temperature crystal structure of RS-thiocamphor

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1524/zkri.219.9.580.44038 ◽

2004 ◽

Vol 219 (9) ◽

Cited By ~ 1

Author(s):

E. Louise R. Robins ◽

Michela Brunelli ◽

Asiloé J. Mora ◽

Andrew N. Fitch

Keyword(s):

Crystal Structure ◽

Phase Transitions ◽

Low Temperature ◽

Room Temperature ◽

Cubic Phase ◽

X Ray Diffraction ◽

Orthorhombic Space Group ◽

Two Phase ◽

X Ray ◽

Low Temperature Crystal Structure

AbstractDSC and high-resolution powder X-ray diffraction measurements in the range 295 K–100 K show that RS-thiocamphor undergoes two phase transitions. The first, at around 260 K on cooling, is from the room-temperature body-centred-cubic phase to a short-lived intermediate. At 258 K the low-temperature form starts to appear. The crystal structure of the latter is orthorhombic, space group

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Synthese und Kristallstrukturen von N-[ω-(Dimethylammonio)alkyl]- N´,N´,N´´,N´´-tetramethylguanidinium-chlorid-tetraphenylboraten / Synthesis and Crystal Structures of N-[ω-(Dimethylammonio)alkyl]-N´,N´,N´´,N´´- tetramethylguanidinium Chloride Tetraphenylborates

Zeitschrift für Naturforschung B ◽

10.1515/znb-2010-0713 ◽

2010 ◽

Vol 65 (7) ◽

pp. 907-916 ◽

Cited By ~ 1

Author(s):

Ioannis Tiritiris ◽

Falk Lissner ◽

Thomas Schleid ◽

Willi Kantlehner

Keyword(s):

Crystal Structure ◽

Low Temperature ◽

Hydrogen Bonds ◽

Crystal Structures ◽

Room Temperature ◽

Chloride Ions ◽

Monoclinic Space Group ◽

Temperature Structure ◽

Space Group ◽

Temperature Modification

Dicationic N,N´,N´,N´´,N´´-pentasubstituted guanidinium dichlorides 4a, b are obtained from the chloroformamidinium salt 2 and diamines 3a, b. N-[2-(Dimethylammonio)ethyl]-N´,N´,N´´,N´´-tetramethylguanidinium chloride tetraphenylborate (5a) and N-[3-(dimethylammonio)propyl]-N´,N´,N´´,N´´-tetramethylguanidinium chloride tetraphenylborate (5b) were synthesized from 4a, b by anion metathesis with one equivalent of sodium tetraphenylborate. The thermal properties of the salts 5a, b were studied by means of DSC methods, and their crystal structures were determined by single-crystal X-ray diffraction analysis. For 5a a solid-solid phase transition is observed at −156 ◦C to a low-temperature structure. The room-temperature modification (α-5a) crystallizes in the centrosymmetric orthorhombic space group Pbca (a = 13.1844(4), b = 13.8007(4), c = 34.7537(11) A° ).The guanidinium ions are interconnected via chloride ions through bridging N-H· · ·Cl hydrogen bonds, providing isolated units. The tetraphenylborate ions show some dynamic disordering in the crystal structure. The low-temperature modification (β -5a) also crystallizes orthorhombically, but in the non-centrosymmetric space group Pna21 (a = 13.1099(4), b = 69.1810(11), c = 13.5847(5) A° ) and consists of four crystallographically independent cations and anions in the unit cell. Compared with the room-temperature structure, a similar N-H· · ·Cl hydrogen bond pattern is observed in the β -phase, but the tetraphenylborate ions are now completely ordered. 5b crystallizes in the monoclinic space group P21/c (a = 10.8010(3), b = 14.1502(5), c = 20.9867(9) A° , β = 94.322(1)◦). In the crystal structure the guanidinium ions are linked via chloride ions through N-H· · ·Cl hydrogen bonds, but in contrast to 5a two infinite strands are formed along the a axis with the tetraphenylborate ions interspersed between them for charge compensation.

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

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989021010422 ◽

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.

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Order-Disorder Phase Transition in NaBD4

Materials Science Forum ◽

10.4028/www.scientific.net/msf.443-444.287 ◽

2004 ◽

Vol 443-444 ◽

pp. 287-290 ◽

Cited By ~ 65

Author(s):

P. Fischer ◽

Andreas Züttel

Keyword(s):

Crystal Structure ◽

Phase Transition ◽

Low Temperature ◽

Neutron Diffraction ◽

Room Temperature ◽

Structure Model ◽

Space Group ◽

Disorder Phase Transition ◽

Low Temperature Crystal Structure ◽

Disorder Type

By means of neutron diffraction the low-temperature crystal structure of NaBD4 has been determined. At 10 K the lattice parameters are a = 4.332(1) Å and c = 5.869(1) Å. Deuterium is found in a tetrahedral arrangement [sites (8g)] around B. The symmetry corresponds to space group P42/nmc. For room temperature the structure model for NaBD4 of Davis and Kennard with disordered deuterium distributed over two sites has been revised to space group Fm-3 m. Thus the 190 K phase transition known from specific heat measurements is of order-disorder type, caused by reorientations of BD4 tetrahedra.

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Low-temperature redetermination of benzofurazan 1-oxide

Acta Crystallographica Section E Structure Reports Online ◽

10.1107/s1600536809017036 ◽

2009 ◽

Vol 65 (6) ◽

pp. o1275-o1275 ◽

Cited By ~ 2

Author(s):

Seik Weng Ng

Keyword(s):

Crystal Structure ◽

Low Temperature ◽

Room Temperature ◽

Membered Ring ◽

Temperature Structure ◽

Double Bonds ◽

Acta Cryst ◽

Low Temperature Crystal Structure

In the six-membered ring of the low-temperature crystal structure of benzofurazan 1-oxide, C6H4N2O2, the two C atoms adjacent to the N atoms are linked by a delocalized aromatic bond [1.402 (2) Å]; each is connected to its neighbour by a longer, more localized, bond [1.420 (2), 1.430 (2) Å]. However, the next two bonds in the ring approximate double bonds [1.357 (2), 1.366 (2) Å]. As such, the six-membered ring is better described as a cyclohexadiene system, in contrast to the description in the room-temperature structure reported by Britton & Olson (1979) [Acta Cryst.B35, 3076–3078].

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Low temperature crystal structure, experimental atomic charges and electrostatic potential of ammonium decavanadate hexahydrate (NH4)V10O28·6H2O

Journal of the Serbian Chemical Society ◽

10.2298/jsc0706545b ◽

2007 ◽

Vol 72 (6) ◽

pp. 545-554 ◽

Cited By ~ 4

Author(s):

Goran Bogdanovic ◽

Nada Bosnjakovic-Pavlovic ◽

Bire Spasojevic-De ◽

Eddine Ghermanic ◽

Ubavka Mioc

Keyword(s):

Crystal Structure ◽

Low Temperature ◽

Hydrogen Bonds ◽

Electrostatic Potential ◽

Water Molecules ◽

Atomic Charges ◽

Atomic Group ◽

Hydrogen Atoms ◽

X Ray ◽

Low Temperature Crystal Structure

The X-ray structure of ammonium decavanadate hexahydrate was redetermined at a low temperature (100 K) in order to locate the hydrogen sites and to study the hydrogen bonds. The hydrogen atoms were assigned to the appropriate atomic group, NH4 + cations, and water molecules, missing to the best of our knowledge in the literature. A kappa refinement was performed to estimate the experimental atomic charges. These charges were used to generale the electrostatic potential on the molecular surfaces of decavanadate polyanions isolated from the influence of the crystal lattice. Comparisons with previous theoretical (ab initio) calculations were made and are also discussed. .

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Infrared spectra of the ammonium ion in crystals. Part VIII. Spectroscopic criteria of highly-bent hydrogen bonds

Canadian Journal of Chemistry ◽

10.1139/v80-136 ◽

1980 ◽

Vol 58 (9) ◽

pp. 867-874 ◽

Cited By ~ 14

Author(s):

Osvald Knop ◽

Wolfgang J. Westerhaus ◽

Michael Falk

Keyword(s):

Low Temperature ◽

Hydrogen Bonds ◽

Infrared Spectra ◽

Room Temperature ◽

Ammonium Ion ◽

Temperature Transition ◽

Increasing Temperature

Available evidence suggests that (1) the stretching frequencies of highly-bent hydrogen bonds decrease with increasing temperature, regardless of whether the bonds are static or dynamic in character, to a single acceptor or to several competing acceptors; and (2) departures from symmetric trifurcation (or bifurcation) toward asymmetric situations lower the stretching frequency. In further support of these criteria isotopic probe ion spectra between 10 K and room temperature have been obtained for taurine and for trigonal (NH4)2MF6 (M = Si, Ge, Sn, Ti). Evidence of a low-temperature transition at 100(10) K in trigonal (NH4)2SnF6 is presented, and existence of the previously reported transition at 38.6 K in trigonal (NH4)2SiF6 is confirmed. Symmetry changes associated with these transitions are discussed.

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Crystal structure of the new hybrid material bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989015019933 ◽

2015 ◽

Vol 71 (11) ◽

pp. 1384-1387

Author(s):

Marwen Chouri ◽

Habib Boughzala

Keyword(s):

Crystal Structure ◽

Aqueous Solution ◽

Hydrogen Bonds ◽

Room Temperature ◽

Molar Ratio ◽

Water Molecules ◽

Site Symmetry ◽

Two Dimensional ◽

Slow Evaporation ◽

Solution Ph

The title compound bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate, (C6H14N2)2[Bi2Cl10]·2H2O, was obtained by slow evaporation at room temperature of a hydrochloric aqueous solution (pH = 1) containing bismuth(III) nitrate and 1,4-diazabicyclo[2.2.2]octane (DABCO) in a 1:2 molar ratio. The structure displays a two-dimensional arrangement parallel to (100) of isolated [Bi2Cl10]4−bioctahedra (site symmetry -1) separated by layers of organic 1,4-diazoniabicyclo[2.2.2]octane dications [(DABCOH2)2+] and water molecules. O—H...Cl, N—H...O and N—H...Cl hydrogen bonds lead to additional cohesion of the structure.

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