Synthesis and Molecular Structures of 2-Trimethylsilyl-, 2-Trimethylgermyl-, and 2-Trimethylstannyl-pyridines

1999 ◽  
Vol 54 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Frank Riedmiller ◽  
Alexander Jockisch ◽  
Hubert Schmidbaur
Keyword(s):  
Quantum Chemical ◽  
Crystal And Molecular Structure ◽  
Variable Temperature ◽  
Intrinsic Property ◽  
Molecular Structures ◽  
Grignard Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nitrogen Heteroatom

5-Methyl-2-trimethylsilyl-pyridine (1) has recently been prepared via the “in situ” Grignard reaction of 1-bromo-5-methyl-pyridine with magnesium and trimethylchlorosilane in refluxing tetrahydrofuran (thf) and structurally characterized. 2-Trimethylgermyl- (2) and 2- trimethylstannyl-pyridine (3) were now obtained from 2-bromo-pyridine through metallation (with n-BuLi) and treatment of the intermediates with Me3GeBr and Me3SnCl, respectively, in diethylether/ thf at -70°C. The crystal and molecular structure of compound 2 has been determined by low temperature (in situ) single crystal X-ray diffraction methods. There is a significant bending of the Me3Ge substituent towards the nitrogen heteroatom [Ge-C-N = 114.7(2)°]. This phenomenon is known from previous studies of the silicon analogue 1 to be not due to intramolecular (peripheral) Si/Ge←N coordination, but to be rather an intrinsic property of the heteroarene skeleton, as also confirmed by quantum-chemical calculations. Furthermore, there is no evidence for intermolecular coordination in the crystals. Such interactions could also be ruled out for the solution state of 2 and 3 through variable temperature multinuclear NMR investigations.

Molecular motions of a tetraphenylethylene-derived AIEgen directly monitored through in situ variable temperature single crystal X-ray diffraction

CrystEngComm ◽  
2021 ◽  
Author(s):  
Wei Meng ◽  
Lin Du ◽  
Lin Sun ◽  
Lian Zhou ◽  
Xiaopeng Xuan ◽  
...  
Keyword(s):  
Single Crystal ◽  
Phenyl Ring ◽  
Functional Group ◽  
Variable Temperature ◽  
Molecular Motions ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Conformation Changes

One organic functional group was introduced to distinguish the four phenyl ring of tetraphenylethylene, and the In situ temperature-dependent crystal structures were determined to exhibit the conformation changes of tert-butyl...

scholarly journals High-temperature in situ crystallographic observation of reversible gas sorption in impermeable organic cages

2015 ◽  
Vol 112 (46) ◽  
pp. 14156-14161 ◽  
Author(s):  
Seung Bin Baek ◽  
Dohyun Moon ◽  
Robert Graf ◽  
Woo Jong Cho ◽  
Sung Woo Park ◽  
...  
Keyword(s):  
Single Crystal ◽  
High Temperatures ◽  
Direct Detection ◽  
Variable Temperature ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dynamic Motion

Crystallographic observation of adsorbed gas molecules is a highly difficult task due to their rapid motion. Here, we report the in situ single-crystal and synchrotron powder X-ray observations of reversible CO2 sorption processes in an apparently nonporous organic crystal under varying pressures at high temperatures. The host material is formed by hydrogen bond network between 1,3,5-tris-(4-carboxyphenyl)benzene (H3BTB) and N,N-dimethylformamide (DMF) and by π–π stacking between the H3BTB moieties. The material can be viewed as a well-ordered array of cages, which are tight packed with each other so that the cages are inaccessible from outside. Thus, the host is practically nonporous. Despite the absence of permanent pathways connecting the empty cages, they are permeable to CO2 at high temperatures due to thermally activated molecular gating, and the weakly confined CO2 molecules in the cages allow direct detection by in situ single-crystal X-ray diffraction at 323 K. Variable-temperature in situ synchrotron powder X-ray diffraction studies also show that the CO2 sorption is reversible and driven by temperature increase. Solid-state magic angle spinning NMR defines the interactions of CO2 with the organic framework and dynamic motion of CO2 in cages. The reversible sorption is attributed to the dynamic motion of the DMF molecules combined with the axial motions/angular fluctuations of CO2 (a series of transient opening/closing of compartments enabling CO2 molecule passage), as revealed from NMR and simulations. This temperature-driven transient molecular gating can store gaseous molecules in ordered arrays toward unique collective properties and release them for ready use.

Photochemische Reaktionen von Übergangsmetall-Organyl-Komplexen mit Olefinen, XVI [1]: Photochemisch induzierte Cycloadditionen von Diphenylacetylen an Tricarbonyl(η5-2,4-dimethyl-2,4-pentadien-1-yl)mangan / Photochemical Reactions of Transition Metal Organyl Complexes with Olefins, XVI [1]: Photochemically Induced Cycloadditions of Diphenylacetylene to Tricarbonyl(η5-2,4-dimethyl-2,4-pentadien-1-yl)manganese

1996 ◽  
Vol 51 (10) ◽  
pp. 1473-1485 ◽  
Author(s):  
Cornelius G. Kreiter ◽  
Ernst-Christian Koch ◽  
Walter Frank ◽  
Guido J. Reiß
Keyword(s):  
Mass Spectra ◽  
Photochemical Reactions ◽  
Molecular Structures ◽  
Manganese Complexes ◽  
Formation Mechanisms ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray

Upon UV irradiation in THF at 208 K tricarbonyl(η5-2,4-dimethyl-2,4-pentadien-1-yl)- manganese (1) yields solvent stabilized, very reactive dicarbonyl(η5-2,4-dimethyl-2,4-pentadien-1-yl)(tetrahydrofuran)manganese (2), which reacts in situ with one or two molecules of diphenylacetylene (3) and yields four manganese complexes and 1,3-dimethyl-5,6-diphenyl-bicyclo[3.2.1]oct-2-ene-7-one (5), which were separated by HPL chromatography. In addition to tricarbonyl η5-4,6 -dimethyl-1,2-diphenyl-cyclohepta-2,4-dien-1-yl)manganese (4) formed by [5+2]cycloaddition and successive 1,4-H shift, tricarbonyl{ 1′,2′,5′-η-5-methyl-2,3 -diphenyl-5- (2′-methyl-4′,5′-diphenyl-penta-1′,4′-dien-1′,5′-diyl)cyclopent-2-en-1 -one-κ-O}manganese (6) is isolated with a ligand, formed from 2,4-dimethyl-2,4-pentadien-1-yl, two units of 3 and one carbon monoxide. The ligands of tricarbonyl{ 1-4,2′-η-4,6 -dimethyl-1,2-diphenyl-5-(E-1′,2′- diphenyl-vinylen)cyclohepta-1,3-diene}manganese (7), and tricarbonyl{η5-4,6 -dimethyl-1,2-diphenyl-7-(E-1′,2′-diphenyl-vinyl)cyclohepta-2,4-dien-1-yl}m anganese (8) are formed from 2,4-dimethyl-2,4-pentadien-1-yl and of two molecules of 3 each. The crystal and molecular structures of 5 and 6 have been determined by single crystal X-ray diffraction. 5 crystallizes in the triclinic space group P1̅ , a = 992.0(2) pm, b = 996.8(2) pm, c = 1021.0(2) pm, a = 77.67(3)°, β = 61.17(3)°, γ = 88.68(3)°. Complex 6 crystallizes also in the triclinic space group P1̅ ,a = 1023.2(2) pm, b - 1113.8(2) pm, c = 1567.9(3) pm, α = 82.88(3)°, β = 86.93(3)°, 7 = 63.53(3)°. The constitutions of 4, 7 and 8 were elucidated from the IR, NMR and mass spectra. Possible formation mechanisms for the compounds 4-8 are proposed. Complex 7 shows hindered rotations of two phenyl groups with different barriers of energy ΔG≠316 = 68.8 kJ/mol, „ΔH≠ = 67.9 ± 0.7 kJ/mol, ΔS≠ = -2 ± 2 J/mol · K and ΔG≠296 = 60.6 kJ/mol, ΔH≠ = 57.7 ± 1.0 kJ/mol, ΔS≠ = -10 ± 2 J/mol·K due to steric interactions.

The Crystal and Molecular Structure of Pentane-2,4-dionato-(2,3,5,6-tetrahepto-2,3-dicarbomethoxo[2.2.1]bicycloheptadiene)rhodium(I), Rh(C5H7O2) (C7H6(CO2CH3)2)

1975 ◽  
Vol 53 (18) ◽  
pp. 2707-2713 ◽  
Author(s):  
Debbie Allen ◽  
Colin James Lyne Lock ◽  
Graham Turner ◽  
John Powell
Keyword(s):  
Crystal And Molecular Structure ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Intensity Data ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Crystal And Molecular Structures ◽  
Square Planar ◽  
Rhodium Atom

The crystal and molecular structures of pentane-2,4-dionato-(2,3,5,6-tetrahapto-2,3-dicarbomethoxo[2.2.1]bicycloheptadienerhodium(I), Rh(C5H7O2)(C7H6(CO2CH3)2), have been measured by single crystal X-ray diffraction. The orange crystals are monoclinic, space group P21/c, Z = 4, a = 9.245(4), b = 9.003(4), c = 21.680(15) Å, β = 113.41(5)°. The calculated and observed densities are 1.645 and 1.642(5) respectively. Intensity data were collected on a Syntex [Formula: see text] diffractometer and a full matrix least squares refinement on 3010 observed reflections leads to a conventional R = 0.0660. The structure can be considered as a roughly square planar arrangement of ligands around the rhodium atom composed of two β-ketoenolate oxygen atoms (Rh—O, 2.037(5) and 2.025(5) Å ) and the centers of the two ethylenic groups. The Rh—C distances for the olefin group attached to the two carbomethoxo groups, 2.117(8), 2.108(8) Å, appear to be slightly larger than those for the other olefinic group, 2.087(7), 2.082(6), and the corresponding C=C distances of 1.375(10) and 1.410(9) Å are different at the 95% confidence level.

Tautomeric polymorphism of the neuroactive inhibitor kynurenic acid

2019 ◽  
Vol 75 (6) ◽  
pp. 793-805
Author(s):  
Dorota Pogoda ◽  
Jan Janczak ◽  
Sylwia Pawlak ◽  
Michael Zaworotko ◽  
Veneta Videnova-Adrabinska
Keyword(s):  
Solid State ◽  
Kynurenic Acid ◽  
Variable Temperature ◽  
Neurological Diseases ◽  
Crystal Form ◽  
Phase Behaviour ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

Kynurenic acid (KYN; systematic name: 4-hydroxyquinoline-2-carboxylic acid, C10H7NO3) displays a therapeutic effect in the treatment of some neurological diseases and is used as a broad-spectrum neuroprotective agent. However, it is understudied with respect to its solid-state chemistry and only one crystal form (α-KYN·H2O) has been reported up to now. Therefore, an attempt to synthesize alternative solid-state forms of KYN was undertaken and six new species were obtained: five solvates and one salt. One of them is a new polymorph, β-KYN·H2O, of the already known KYN monohydrate. All crystal species were further studied by single-crystal and powder X-ray diffraction, thermal and spectroscopic methods. In addition to the above methods, differential scanning calorimetry (DSC), in-situ variable-temperature powder X-ray diffraction and Raman microscopy were applied to characterize the phase behaviour of the new forms. All the compounds display a zwitterionic form of KYN and two different enol–keto tautomers are observed depending on the crystallization solvent used.

Preparation and structure of 4-(dimethylamino)thiopivalophenone – intermolecular interactions in the crystal

2019 ◽  
Vol 74 (11-12) ◽  
pp. 825-831
Author(s):  
Jürgen Voss ◽  
Dirk Buddensiek ◽  
Gunadi Adiwidjaja
Keyword(s):  
Molecular Structure ◽  
Carbon Disulfide ◽  
Quantum Chemical ◽  
Electron Distribution ◽  
Significant Contribution ◽  
Crystal And Molecular Structure ◽  
Resonance Structure ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
X Ray

Abstract4-(Dimethylamino)thiopivalophenone was prepared from 4-bromo-N,N-dimethylaniline, pivalonitrile and carbon disulfide. Its crystal and molecular structure was determined by single-crystal X-ray diffraction. The experimentally determined bond distances, bond angles and torsion angles are indicative of a significant contribution of a dipolar (“quinodimethane”) resonance structure to the electron distribution in the molecule. Quantum chemical calculations corroborate these results. The calculations, furthermore, provide an explanation of the arrangement of the molecules in the crystal.

Structures of Energetic Acetylene Derivatives HC≡CCH2ONO2, (NO2)3CCH2C≡CCH2C(NO2)3 and Trinitroethane, (NO2)3CCH3

2013 ◽  
Vol 68 (5-6) ◽  
pp. 719-731 ◽  
Author(s):  
Thomas M. Klapötke ◽  
Burkhard Krumm ◽  
Richard Moll ◽  
Alexander Penger ◽  
Stefan M. Sproll ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Room Temperature ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Polar Solvents ◽  
X Ray ◽  
Nmr Study ◽  
Acetylene Derivatives

The molecular structures and relative ratios of the two conformers (anti and gauche) of HCCCH2ONO2 detected in the gas phase at room temperature have been determined by electron diffraction. The results are discussed on the basis of quantum chemical calculations. The molecular structures of (NO2)3CCH2C≡CCH2C(NO2)3 and (NO2)3CCH3 have been determined by X-ray diffraction. A109Ag NMR study was performed for silver trinitromethanide Ag[C(NO2)3] in various polar solvents.

Gilded Chalices: Tetra-aurated Calix[4]arenes

2014 ◽  
Vol 69 (11-12) ◽  
pp. 1061-1072 ◽  
Author(s):  
Ulf H. Strasser ◽  
Beate Neumann ◽  
Hans-Georg Stammler ◽  
Raphael J. F. Berger ◽  
Norbert W. Mitzela
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Quantum Chemical ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Elemental Analyses ◽  
One Step ◽  
Energy Of Formation

Abstract 5,11,17,23-Tetrakis(trimethylsilylethynyl)-25,26,27,28-tetra-n-propoxycalix[4]arene (1) was synthesised in two steps starting from 25,26,27,28-tetra-n-propoxycalix[4]arene, and the structure of 1 was determined by X-ray diffraction. Compound 1 was desilylated (K2CO3) to give 5,11,17,23- tetrakis(ethynyl)-25,26,27,28-tetra-n-propoxycalix[4]arene (2), which was tetra-aurated under basic conditions (NaOEt, THF) with a series of phosphane-gold chlorides (o-Tol3PAuCl, Ph3PAuCl, Ph2MePAuCl, PhMe2PAuCl, Me3PAuCl, Cy3PAuCl, t-Bu3PAuCl) to afford in good to excellent yields the tetra-aurated tetraethynylcalix[4]arene species 3-9 in one step [with phosphane ligands o-Tol3P (3), Ph3P (4), Ph2MeP (5), PhMe2P (6), Me3P (7), Cy3P (8), t-Bu3P (9)]. All compounds were characterised by 1H NMR and infrared spectroscopy, mass spectrometry and by elemental analyses, additionally 3, 4, 5, 8 and 9 by 13C{1H}, and 3-6, 8 and 9 by 31P{1H} NMR spectroscopy. The molecular structures of complexes 3 and 9 were determined by X-ray diffraction and show pinched-cone conformations, but neither intra- nor intermolecular attractive aurophilic Au···Au contacts. The acceptor ability of complexes 3 and 9 was investigated by complexation attempts with various phosphane-gold chlorides and xenon gas under pressure, but interactions could not be determined experimentally. The formation of a complex between xenon and gilded calix[4]arene could, however, be predicted for fluorine-substituted species and with very small phosphane ligands (PH3) on the basis of quantum-chemical calculations; the energy of formation is 9:6 kJ mol-1. The crystal structure of Ph2MePAuCl was also determined and shows Au···Au-bonded dimers.

Variable temperature in situ X-ray diffraction study of mechanically activated synthesis of calcium titanate, CaTiO3

2003 ◽  
Vol 38 (7) ◽  
pp. 1203-1213 ◽  
Author(s):  
Ivana Radosavljevic Evans ◽  
Judith A.K. Howard ◽  
Tatjana Sreckovic ◽  
Momcilo M. Ristic
Keyword(s):  
Diffraction Study ◽  
Variable Temperature ◽  
Calcium Titanate ◽  
X Ray Diffraction ◽  
X Ray

The crystal and molecular structure of syn-9-phenyl-2,11-dithia[3,3]metacyclophane

1984 ◽  
Vol 62 (4) ◽  
pp. 661-666 ◽  
Author(s):  
Willem Anker ◽  
Kathy A. Beveridge ◽  
Gordon W. Bushnell ◽  
Reginald H. Mitchell
Keyword(s):  
Crystal Structure ◽  
Crystal And Molecular Structure ◽  
Variable Temperature ◽  
Phenyl Group ◽  
Outer Side ◽  
X Ray Diffraction ◽  
X Ray ◽  
Out Of Plane ◽  
Boat Form ◽  
The Mean

The crystal structure of syn-9-phenyl-2,11-dithia[3,3]metacyclophane, 6, has been determined by single crystal X-ray diffraction and refined to an R value of 0.0723. The crystal structure is triclinic with a = 9.573(2), b = 12.010(4), c = 8.433(2) Å, α = 108.02(2)°, β = 95.95(2)°, γ = 102.25(3)°, and the space group is [Formula: see text] with two molecules per cell, D(meas) = 1.313 g cm−3, D(calc) = 1.306 g cm−3. The bridging S atoms differ in their conformations so that the S … S distance is 6.391 Å. The metacyclophane rings have a distance of 3.57 Å between their centres and form a dihedral angle of 20.5°. The phenyl substituent forms an angle of 78.6° with the adjacent ring and has an ortho H-atom very close to the internal H-atom of the opposite ring. The phenyl substituted aromatic ring is non-planar and in a shallow boat form, the ring atoms C(11) (internal) and C(14) being 0.038(4) and 0.037(5) Å out-of-plane on the outside, the methylene C substituents are 0.212(5) and 0.199(5) Å out-of-plane on the inside. The first atom of the phenyl group is in the bowsprit position and is 0.274(4) Å above the mean plane on the outer side of the molecule. The opposite metacyclophane ring is less strained but in a similar boat form with the methylene C-atoms 0.092(4) and 0.067(6) Å to the inside. The mean bond angle at S is 103.5(2)°, the angles at C (methylene) range from 113.3(3)° to 118.0(3)°.The variable temperature 1Hmr spectra results are consistent with the syn conformer 6 being dominant in solution and frozen at temperatures <60 °C as conformer A, with only relatively restricted further twisting of the biphenyl being found at ambient temperature.

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