scholarly journals Remarkable reversal of 13C-NMR assignment in d1, d2 compared to d8, d9 acetylacetonate complexes: analysis and explanation based on solid-state MAS NMR and computations

2020 ◽  
Vol 22 (15) ◽  
pp. 8048-8059
Author(s):  
Anders B. A. Andersen ◽  
Ari Pyykkönen ◽  
Hans Jørgen Aa. Jensen ◽  
Vickie McKee ◽  
Juha Vaara ◽  
...  
Keyword(s):  
Solid State ◽  
13C Nmr ◽  
Nmr Assignment ◽  
Mas Nmr ◽  
Electron Configuration ◽  
Paramagnetic Shifts ◽  
C Nmr

The variation in 13C NMR paramagnetic shifts as a function of d-electron configuration was explained by NMR shielding calculations.

scholarly journals Structural Investigations of C-Nitrosobenzenes. Part 3.1 Solid-state and Solution 13C NMR Studies, and Crystal Structure of E-(4-CIC6H4NO)2

1999 ◽  
Vol 23 (3) ◽  
pp. 202-203
Author(s):  
Daniel A. Fletcher ◽  
Brian G. Gowenlock ◽  
Keith G. Orrell ◽  
David C. Apperley ◽  
Michael B. Hursthouse ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
13C Nmr ◽  
Nmr Studies ◽  
Structural Investigations ◽  
Nmr Data ◽  
C Nmr

Solid-state and solution 13C NMR data for the monomers and dimers of 3- and 4-substituted nitrosobenzenes, and the crystal structure of E-(4-CIC6H4NO)2 are reported.

Solid state stereochemistry of crown ethers: X-ray crystal structure and 13C NMR studies of the LiNCS complex of 1,4,7,11-tetraoxacyclotetradecane

2000 ◽  
Vol 78 (3) ◽  
pp. 316-321
Author(s):  
G W Buchanan ◽  
A B Driega ◽  
G PA Yap
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ether ◽  
13C Nmr ◽  
Title Complex ◽  
Nmr Studies ◽  
Nmr Spectrum ◽  
X Ray ◽  
Large Amplitude Motion ◽  
C Nmr

The title complex is asymmetric in the crystal due to the spatial orientation of the NCS function. The space group has been determined to be P21 with a = 9.496(3), b = 8.736(3), c = 9.676(3) Å, β = 117.859(5)°, and Z = 2. The solid state 13C NMR spectrum is consistent with the lack of symmetry in the crystal and there is little evidence for large amplitude motion in the macrocycle as determined from the dipolar dephased spectrum.Key words: macrocyclic crown ether, lithium complex.

scholarly journals 13C CPMAS NMR as a Tool for Full Structural Description of 2-Phenyl Substituted Imidazoles That Overcomes the Effects of Fast Tautomerization

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3770
Author(s):  
Nikola Burdzhiev ◽  
Anife Ahmedova ◽  
Boris Borrisov ◽  
Robert Graf
Keyword(s):  
Solid State ◽  
Gas Phase ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Spectroscopic Method ◽  
Mas Nmr ◽  
Structural Description ◽  
Tautomeric Forms ◽  
Cp Mas Nmr ◽  
13C Cp Mas Nmr

Tautomerization of 2-phenylimidazolecarbaldehydes has not been studied in detail so far, although this process is a well-known phenomenon for imidazole derivatives. That is why we focus our study on a series of 2-phenylimidazolecarbaldehydes and their parent alcohols that were synthesized and studied by detailed 1H and 13C NMR in solution and in the solid state. The apparent problem is that the fast tautomerization impedes the full structural description of the compounds by conventional 13C NMR measurements. Indeed, the 13C NMR spectra in solution exhibit poor resolution, and in most cases, signals from the imidazole ring are not detectable. To avoid this problem, we used 13C CP-MAS NMR as an alternative spectroscopic method for unambiguous spectroscopic characterization of the studied series of 2-phenylimidazoles. The data were analyzed in combination with quantum chemical DFT-GIAO methods by considering the tautomerization process and the intermolecular interactions. The DFT (B3LYP/6-31G(d,p)) calculations allowed to identify and suggest the preferred tautomer in the gas phase and in DMSO solvent, which for alcohols are (2-phenyl-1H-imidazol-4-yl)methanol and its analogs, and for the aldehydes are the 2-phenyl-1H-imidazole-5-carbaldehydes. The gas-phase calculated energy differences between the two possible tautomeric forms are in the range 0.645–1.415 kcal/mol for the alcohols and 2.510–3.059 kcal/mol for the aldehydes. In the DMSO solvent, however, for all compounds, the calculated energy differences go below 1.20 kcal/mol. These data suggest that both tautomeric forms of the studied 2-phenylimidazoles can be present in solution at room temperature. Our data from detailed 2D NMR measurements in the solid state (1H-13C HETCOR and 1H-1H double-quantum coherence MAS NMR) suggested that also in the solid state both tautomers coexist in different crystalline domains. This fact does not obscure the 13C CP-MAS NMR spectra of the studied 2-phenyl substituted imidazoles and suggests this spectroscopic method as a powerful tool for a complete structural description of tautomeric systems with aromatic conjugation.

scholarly journals Studies of Fluxionality in Pentachlorocyclopentadienylmercurials RHgC5Cl5 by Solution and Solid State 13C NMR and by 35Cl NQR Spectroscopy

1986 ◽  
Vol 41 (1-2) ◽  
pp. 175-178
Author(s):  
Gary Wulfsberg ◽  
A. C. Buchanan ◽  
Ira Rubin ◽  
Alarich Weiss ◽  
Daniel A. Davis ◽  
...  
Keyword(s):  
Solid State ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
35Cl Nqr ◽  
Angle Spinning ◽  
C Nmr ◽  
Solid State 13C Nmr

Solution and magic-angle-spinning solid-state 13C NMR spectra are reported for η1-(pentachlorocyclopentadienyl)( pentamethylphenyl) mercury, C6Me5HgC5Cl5 (II). The latter suggests that II is fluxional in the solid state. Some expected consequences of fluxional behavior also appear in the 35Cl NQR spectra of II and several related pentachlorocyclopentadienylmercurials.

scholarly journals Synthetic, Infrared, 1H and 13C NMR Spectral Studies on N-(2-/3-Substituted Phenyl)-4-Substituted Benzenesulphonamides, 4-X’C6H4SO2NH(2-/3-XC6H4), where X’ = H, CH3, C2H5, F, Cl or Br, and X = CH3 or Cl

2005 ◽  
Vol 60 (1-2) ◽  
pp. 106-112 ◽  
Author(s):  
B. Thimme Gowda ◽  
Mahesha Shetty ◽  
K. L. Jayalakshmi
Keyword(s):  
Solid State ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Spectral Studies ◽  
1H And 13C Nmr ◽  
Methyl Group ◽  
Benzene Rings ◽  
Stretching Vibrations ◽  
C Nmr

Twenty three N-(2-/3-substituted phenyl)-4-substituted benzenesulphonamides of the general formula, 4-X’C6H4SO2NH(2-/3-XC6H4), where X’ = H, CH3, C2H5, F, Cl or Br and X = CH3 or Cl have been prepared and characterized, and their infrared spectra in the solid state, 1H and 13C NMR spectra in solution were studied. The N-H stretching vibrations, νN−H, absorb in the range 3285 - 3199 cm−1, while the asymmetric and symmetric SO2 vibrations vary in the ranges 1376 - 1309 cm−1 and 1177 - 1148 cm−1, respectively. The S-N and C-N stretching vibrations absorb in the ranges 945 - 893 cm−1 and 1304 - 1168 cm−1, respectively. The compounds do not exhibit particular trends in the variation of these frequencies on substitution either at ortho or meta positions with either a methyl group or Cl. The observed 1H and 13C chemical shifts of are assigned to protons and carbons of the two benzene rings. Incremental shifts of the ring protons and carbons due to -SO2NH(2-/3-XC6H4) groups in C6H5SO2NH(2-/3-XC6H4), and 4- X’C6H4SO2- and 4-X’C6H4SO2NH- groups in 4-X’C6H4SO2NH(C6H5) are computed and employed to calculate the chemical shifts of the ring protons and carbons in the substituted compounds, 4-X’C6H4SO2NH(2-/3-XC6H4). The computed values agree well with the observed chemical shifts.

scholarly journals Determination of the n-director direction of low bend-angle banana-shaped molecules by solid-state 13C NMR

2014 ◽  
Vol 2 (48) ◽  
pp. 10418-10427 ◽  
Author(s):  
Kazuhiko Yamada ◽  
Eun Woo Lee ◽  
Masaya Hattori ◽  
Susumu Kawauchi ◽  
E.-Joon Choi ◽  
...  
Keyword(s):  
Solid State ◽  
Quantum Chemical Calculations ◽  
13C Nmr ◽  
Quantum Chemical ◽  
Bend Angle ◽  
C Nmr ◽  
Solid State 13C Nmr

Solid-state 13C NMR combined with quantum chemical calculations could determine the n-director direction of low bend-angle banana-shaped molecules.

Molecular Structure of Tri(2-thienyl)borane

1996 ◽  
Vol 51 (12) ◽  
pp. 1811-1814 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Wolfgang Milius ◽  
Elias Molla
Keyword(s):  
Molecular Structure ◽  
Solid State ◽  
Nmr Spectra ◽  
Structural Parameters ◽  
Mas Nmr ◽  
Monoclinic Space Group ◽  
Nmr Spectrum ◽  
Π Interactions ◽  
Cp Mas Nmr ◽  
C Nmr

The molecular structure of tri(2-thienyl)borane (1) was determined [monoclinic, space group P21/ c; a = 12.216(2), b = 7.765(2), c = 12.605(2) Å, β = 93.13(2)°]; two of the three thienyl groups are disordered, as is also indicated by the solid-state 13C CP/MAS NMR spectrum of 1. The 13C NMR spectra of 1 were measured at variable tem perature in solution and the barrier to rotation about the B-C bonds was found to be <35 kJ/mol. Thus, CB(pp)π interactions must be regarded as rather weak, in spite of suggestive δ11 B. δ13C data and structural parameters.

2-Octyl thiophene based three ring mesogens: solid state 13C NMR and XRD investigations

2015 ◽  
Vol 17 (30) ◽  
pp. 19936-19947 ◽  
Author(s):  
B. Veeraprakash ◽  
Nitin P. Lobo ◽  
T. Narasimhaswamy ◽  
A. B. Mandal
Keyword(s):  
Solid State ◽  
High Resolution ◽  
13C Nmr ◽  
Variable Temperature ◽  
Molecular Shape ◽  
Molecular Organization ◽  
X Ray ◽  
Phenyl Rings ◽  
C Nmr ◽  
Solid State 13C Nmr

Molecular organization and molecular order of polymesomorphic thiophene based mesogens were investigated by variable temperature powder X-ray and high resolution solid state 13C NMR, and the higher order for thiophene in contrast to phenyl rings is attributed to molecular shape.

scholarly journals 1,3-Oxazepane-4,7-Diones Compounds: 1H and 13C NMR High-Resolution Spectroscopy (1D and 2D)

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
AbdulKarim-Talaq Mohammad ◽  
Hasnah Osman ◽  
Guan-Yeow Yeap
Keyword(s):  
High Resolution ◽  
13C Nmr ◽  
Phenyl Ring ◽  
Nmr Assignment ◽  
Alkyl Chain ◽  
High Resolution Spectroscopy ◽  
Two Dimensional ◽  
1H And 13C Nmr ◽  
Nmr Techniques ◽  
C Nmr

The complete 1H and 13C NMR assignment of new 1,3-oxazepane-4,7-dione compounds has been obtained using one- and two-dimensional NMR techniques including COSY, HMQC, and HMBC experiments. The data deduced from this study show that the alkyl chain and the phenyl ring are in different planes compared to the oxazepine ring.

Solid state 13C NMR in conducting polymers

1985 ◽  
Vol 46 (9) ◽  
pp. 1595-1601 ◽  
Author(s):  
F. Devreux ◽  
G. Bidan ◽  
A.A. Syed ◽  
C. Tsintavis
Keyword(s):  
Solid State ◽  
Conducting Polymers ◽  
13C Nmr ◽  
Solid State 13C Nmr
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