Struktur und X-X-Elektronendichteverteilung in Diaminoboranen des Typs (RCH3N)2BCH3 mit R = H, CH3

1991 ◽  
Vol 46 (1) ◽  
pp. 84-96 ◽  
Author(s):  
Norbert Niederprüm ◽  
Roland Boese ◽  
Günter Schmid
Keyword(s):  
Crystal Structure ◽  
Electron Density ◽  
Zone Melting ◽  
Infrared Light ◽  
Monoclinic Space Group ◽  
Difference Electron Density ◽  
Orthorhombic Space Group ◽  
Torsion Angles ◽  
Space Group ◽  
The Mean

Using a miniature zone melting device with focused infrared light it was possible to grow crystals of bis(dimethylamino)methylborane (1) and bis(monomethylamino)methylborane (2) at temperatures o f 182 K and 177 K, respectively. The crystal structure and the X - X difference electron density have been determined at temperatures o f 120 K (1) and 115 K (2).1 crystallizes in the orthorhombic space group Pbca with a = 758.87(7), b = 1559.74(12) and c = 1296.73(12) pm. The mean B - N distance is 143.1(3) pm.2 crystallizes in the monoclinic space group P21/c with a = 775.06(6), b = 1533.94(17), c = 1011.06(10) pm and β = 102.669(7)° with intermolecular N ··· H hydrogen bridges. The mean B - N distance is 141.5(2) pm.It is shown that the variation of torsion angles at small angles has more influence on bond lengths than the same or a greater variation at large angles and that it is necessary to pay more attention to the torsion angles ( C - B - N - C ) rather than to the interplanar angles (plane N ,B,N - plane N ,C,C ).

Mono- and difunctional furan-based 1,2,3,5-dithiadiazolyl radicals; preparation and solid state structures of 2,5-[(S2N2C)OC4H2(CN2S2)] and 2,5-[(S2N2C)OC4H2(CN)]

1992 ◽  
Vol 70 (3) ◽  
pp. 919-925 ◽  
Author(s):  
A. Wallace Cordes ◽  
Charles M. Chamchoumis ◽  
Robin G. Hicks ◽  
Richard T. Oakley ◽  
Kelly M. Young ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
The Mean ◽  
Solid State Structures ◽  
Solid State Characterization

The preparation and solid state characterization of the bifunctional radical furan-2,5-bis(1,2,3,5-dithiadiazolyl) 2,5-[(S2N2C)OC4H2(CN2S2)] and the related monofunctional radical 2-cyanofuran-5-(1,2,3,5-dithiadiazolyl) 2,5-[(S2N2C)OC4H2(CN)] are described. The crystal structure of 2,5-[(S2N2C)OC4H2(CN2S2)] is orthorhombic, space group Pna21, and consists of interleaved arrays of dimers, for which the mean interannular [Formula: see text] contact is 3.137 Å. The crystal structure of the monofunctional radical 2,5-[(S2N2C)OC4H2(CN)] is monoclinic, space group P21/n, and consists of a ribbon-like network of dimers (mean interannular [Formula: see text] interconnected by close head-to-tail [Formula: see text] contacts. The dimer units form stacks parallel to z, with a mean interdimer [Formula: see text] separation of 3.956 Å. The similarities and differences between these two crystal structures and those of related benzene-substituted systems are discussed. Keywords: dithiadiazolyl radicals, furan-based diradicals, cyanofuran-based radicals, radical dimers, crystal structures.

Two lithium tricyanomethanide compounds: syntheses and single-crystal structure determination of LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO

2015 ◽  
Vol 70 (3) ◽  
pp. 191-196 ◽  
Author(s):  
Olaf Reckeweg ◽  
Francis J. DiSalvo
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Structure Determination ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Cell Parameters ◽  
New Compounds

AbstractThe new compounds LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO were synthesized and their crystal structures were determined. Li[C(CN)3]·½ (H3C)2CO crystallizes in the orthorhombic space group Ima2 (no. 46) with the cell parameters a=794.97(14), b=1165.1(2) and c=1485.4(3) pm, while LiK[C(CN)3]2 adopts the monoclinic space group P21/c (no. 14) with the cell parameters a=1265.7(2), b=1068.0(2) and c=778.36(12) pm and the angle β=95.775(7)°. Single crystals of K[C(CN)3] were also acquired, and the crystal structure was refined more precisely than before corroborating earlier results.

Darstellung und Kristallstruktur des Bis(diisobutylammonium)-heptasulfids [H2N(i-C4H9)2]2S7 / Synthesis and Crystal Structure of Bis(diisobutylammonium)-heptasulfide [H2N(i-C4H9)2]2S7

1993 ◽  
Vol 48 (12) ◽  
pp. 1732-1736 ◽  
Author(s):  
C. Müller ◽  
P. Böttcher
Keyword(s):  
Crystal Structure ◽  
Orthorhombic Space Group ◽  
Trans Conformation ◽  
Torsion Angles ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
Lattice Constants ◽  
Ethanol Yields ◽  
The Common

The reaction of diisobutylamine, H2S, and sulfur in a mixture of dimethylformamide, formamide, and ethanol yields orange crystals of bis(diisobutylammonium)-heptasulfide. The compound crystallizes in the centrosymmetric orthorhombic space group Pbca, the lattice constants are a = 11.234(4), b = 17.875(7), c = 27.009(10) Å. The S72-chain does not have the common helical all-trans-conformation, but a mixed conformation trans-cis-trans (sequence of the signs of torsion angles + + - - and - - + +).

Darstellung und Kristallstruktur des Bis(trimethylammonium)hexasulflds [HN(CH3)3]2S6 / Preparation and Crystal Structure of Bis(trimethylammonium)hexasulfide [HN(CH3)3]2S6

1994 ◽  
Vol 49 (4) ◽  
pp. 489-493 ◽  
Author(s):  
C. Müller ◽  
P. Böttcher
Keyword(s):  
Crystal Structure ◽  
Monoclinic Space Group ◽  
Trans Conformation ◽  
Torsion Angles ◽  
Space Group ◽  
Lattice Constants ◽  
Ethanol Yields

The reaction of trimethylamine, H2S, and sulfur in ethanol yields orange crystals of bis(trimethylammonium) hexasulfide. The com pound crystallizes in the centrosymmetric monoclinic space group P 2/c. The lattice constants are a = 10.310(7), b = 5.752(2), c = 13.348(10) Å, β = 98.41(6)°. The S26-chain has a helical all-trans-conformation (sequence of the signs of torsion angles +++ and --- ).

79Br, 127I NQR of Diammoniumalkyl Halides and Piperazinium Halides. Crystal Structure of Piperazinium Dibromide Monohydrate and Piperazinium Monoiodide

1989 ◽  
Vol 44 (1) ◽  
pp. 41-55 ◽  
Author(s):  
Jutta Hartmann ◽  
Shi-Qi Dou ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Temperature Range

Abstract The 79Br and 127I NQR spectra were investigated for 1,2-diammoniumethane dibromide, -diiodide, 1,3-diammoniumpropane dibromide, -diiodide, piperazinium dibromide monohydrate, and piperazinium monoiodide in the temperature range 77 ≦ T/K ≦ 420. Phase transitions could be observed for the three iodides. The temperatures for the phase transitions are: 400 K and 404 K for 1,2-diammoniumethane diiodide, 366 K for 1,3-diammoniumpropane diiodide, and 196 K for piperazinium monoiodide.The crystal structures were determined for the piperazinium compounds. Piperazinium dibromide monohydrate crystallizes monoclinic, space group C2/c, with a= 1148.7 pm, 0 = 590.5 pm, c= 1501.6pm, β = 118.18°, and Z = 4. For piperazinium monoiodide the orthorhombic space group Pmn 21 was found with a = 958.1 pm, b = 776.9 pm, c = 989.3 pm, Z = 4. Hydrogen bonds N - H ... X with X = Br, I were compared with literature data.

Untersuchungen an Polyhalogeniden, XXXVI. Zur Kenntnis des Oktaiodid-Ions I82-: Darstellung und Kristallstruktur des [(Crypt-2.2.2)H2]l8, des [Ni(phen)3]I8 · 2CHCl3 und der Bis(N-alkylurotropinium) oktaiodide (UrR)2I8 mit R = Methyl und Ethyl / Studies on Polyhalides, XXXVI. On the Octaiodide Ion I82-: Preparation and Crystal Structure of [(Crypt-2.2.2)H2]I8, of [Ni(phen)3]I8-2CHCl3 and of the Bis(N-alkylurotropinium)octaiodides (UrR)2I8 with R = methyl and ethyl

1998 ◽  
Vol 53 (7) ◽  
pp. 641-652 ◽  
Author(s):  
Arista Gräfe-Kavoosian ◽  
Shida Nafepour ◽  
Klaus Nagel ◽  
Karl-Friedrich Tebbe
Keyword(s):  
Crystal Structure ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Iodine Molecule ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Space Group

Abstract The new compound [(Crypt-2.2.2)H2]I8 has been prepared by the reaction of [(Crypt-2.2.2)H2](I3)2 with iodine in methanol. It crystallizes in the orthorhombic space group Pbcn with a = 11.476 (2), b = 13.589 (2), c = 22.888 (2) Å and Z = 4. The crystal structure has been refined to RF = 0.031 for 1618 reflections. It may be described as a layerlike packing of octaiodide anions I82-and diprotonated 2.2.2-Crypt as cations. The non planar octaiodide anion is built up from two triiodide groups and a bridging iodine molecule.Tris(1, 10-phenanthroline)nickel(II) octaiodide bis(chloroform) crystallizes in the monoclinic space group P21/n with a = 11.683 (8), b = 21.717 (8), c = 20.752 (5) Å, β = 95.03 (5)° and Z = 4 formula units. The crystal structure has been refined to RF = 0.058 for 3894 reflections. The structure consists of two chloroform molecules, octahedrally coordinated complex cations [Ni(phen)3]2+ and nonplanar octaiodide anions I82- each composed of two asymmetric triiodide units I3- weakly associated with an elongated bridging iodine molecule I2.The already known structure of bis(N-methylurotropinium) octaiodide, (UrMe)2I8, has been verified and more accurate crystal data have been collected. The crystal structure has been refined to RF = 0.045 for 1908 reflections. The compound crystallizes in the monoclinic space group P21/c with a = 11.302 (2), b = 9.850 (2), c = 14.188 (2) Å , β = 92.59 (1)° and Z = 2. The anion has the shape of a stretched Z.The structure of bis(N-ethylurotropinium) octaiodide (UrEt)2I8 has been determined and a new configuration (I3-, I5-) for octaiodide ions between Z (I3- · I2 ·I3-) and a “broken” configuration (I3-, I5-) has been observed. The compound crystallizes in the triclinic space group P1̄ with a = 9.741 (3), b = 11.815 (3), c = 15.426 (3) Å, α = 91.80 (2), β = 107.14 (2), γ = 90.04 (2)° and Z = 2. The crystal structure has been refined to RF = 0.037 for 3657 reflections.

Untersuchungen an Polyhalogeniden, XXI [1] Die Ethyltriphenylphosphonium-Polyiodide EtPh3PIn mit n = 3,5 und 7 / Studies of Polyhalides, XXI [1] Ethyltriphenylphosphonium Polyiodides EtPh3PIn with n = 3,5 and 7

1995 ◽  
Vol 50 (11) ◽  
pp. 1685-1691 ◽  
Author(s):  
Karl-Friedrich Tebbe ◽  
Taraneh Farida
Keyword(s):  
Crystal Structure ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Stoichiometric Reaction

The compounds EtPh3PI3, EtPh3PI5 and EtPh3PI7 have been prepared by the stoichiometric reaction of EtPh3PI with iodine in a mixture of dichloromethane and ethanol. EtPh3PI3 cry­stallizes in the monoclinic space group P21/n with a = 1176.7(3) pm, b = 1202.5(3) pm, c = 1565.9(4) pm, β=93.22(2)° and Z = 4. The crystal structure has been refined to RF = 0.043 for 3394 reflections. EtPh3PI5 crystallizes in the monoclinic space group I2/a with a = 1913.9(4) pm, b = 1239.0(2)pm, c = 2435.1(4) pm, β = 115.84(1)° and Z = 8. The crystal structure has been refined to RF =0.052 for 3043 reflections. EtPh3PI7 crystallizes in the orthorhombic space group Pbca with a = 1702.7(4)pm. b = 1952.5(4) pm, c = 1809.8(4) pm und Z = 8. The crystal structure has been refined to RF = 0.053 for 3208 reflections. The structures may be described as layerlike packings of cations Ph3EtP+ and of anions I-3, I-5 and I-7, respectively. The isolated triiodide ion I-3 is slightly asymmetrical and slightly bent as expected. The pentaiodide ion I-5 forms iodine ribbons like a rope ladder. The heptaiodide ion I-7 is composed of pentaiodide groups and iodine molecules connected to puckered anionic layers.

scholarly journals A variable-temperature study of a phase transition in barbituric acid dihydrate

2005 ◽  
Vol 61 (4) ◽  
pp. 464-472 ◽  
Author(s):  
Gary S. Nichol ◽  
William Clegg
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Barbituric Acid ◽  
Crystal Packing ◽  
Variable Temperature ◽  
Mirror Plane ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Acta Cryst ◽  
Space Group

The crystal structure of barbituric acid dihydrate (C4H4N2O3·2H2O) has twice been reported as orthorhombic, space group Pnma, with all atoms (except for CH2 H atoms) lying on the mirror plane [Al-Karaghouli et al. (1977). Acta Cryst. B33, 1655–1660; Jeffrey et al. (1961). Acta Cryst. 14, 881–887]. The present study has found that at low temperatures, below 200 K, the crystal structure is no longer orthorhombic but is non-merohedrally twinned monoclinic, space group P21/n. This phase is stable down to 100 K. Above 220 K the crystal structure is orthorhombic, and between 200 and 220 K the structure undergoes a phase change, with the monoclinic-to-orthorhombic phase transition itself taking place at around 216–217 K. The size of the β angle in the monoclinic structure is temperature dependent; at 100 K β is around 94° and it decreases in magnitude towards 90° as the temperature increases. Although the hydrogen-bonding motifs are the same for both crystal systems, there are significant differences in the crystal packing, in particular the out-of-plane displacement of the two water molecules and the sp 3-hybridized C atom of barbituric acid.

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.

Synthesis and photophysical properties of 2,5,8,11-tetrakis(5-hexylthiophen-2-yl)tetrathieno[2,3-a:3′,2′-c:2′′,3′′-f:3′′′,2′′′-h]naphthalene

2013 ◽  
Vol 69 (6) ◽  
pp. 634-637 ◽  
Author(s):  
Libin Gao
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Photophysical Properties ◽  
Planar Geometry ◽  
Monoclinic Space Group ◽  
Slow Evaporation ◽  
Space Group ◽  
Compound C ◽  
Alkyl Side Chains ◽  
The Mean

The title compound, C58H64S8, has been prepared by Pd-catalysed direct C—H arylation of tetrathienonaphthalene (TTN) with 5-hexyl-2-iodothiophene and recrystallized by slow evaporation from dichloromethane. The crystal structure shows a completely planar geometry of the TTN core, crystallizing in the monoclinic space groupP21/c. The structure consists of slipped π-stacks and the interfacial distance between the mean planes of the TTN cores is 3.456 (5) Å, which is slightly larger than that of the comparable derivative of tetrathienoanthracene (TTA) with 2-hexylthiophene groups. The packing in the two structures is greatly influenced by both the aromatic core of the structure and the alkyl side chains.

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