Symmetry and 1H NMR chemical shifts of short hydrogen bonds: impact of electronic and nuclear quantum effects

2020 ◽  
Vol 22 (9) ◽  
pp. 4884-4895 ◽  
Author(s):  
Shengmin Zhou ◽  
Lu Wang
Keyword(s):  
Hydrogen Bonds ◽  
1H Nmr ◽  
Chemical Shifts ◽  
Quantum Effects ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Nuclear Quantum Effects ◽  
Short Hydrogen Bonds

Electronic and nuclear quantum effects determine the symmetry and highly downfield 1H NMR chemical shifts of short hydrogen bonds.

15N, 13C, and 1H NMR spectra of acylated ureas and thioureas

1987 ◽  
Vol 52 (10) ◽  
pp. 2474-2481 ◽  
Author(s):  
Josef Jirman ◽  
Antonín Lyčka
Keyword(s):  
1H Nmr ◽  
Electron Acceptor ◽  
Sulfur Atom ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
Coupling Constants ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Better Than

A series of 1-acylated and 1,3-diacylated (acyl = acetyl or benzoyl) ureas and thioureas have been prepared and their proton-coupled and proton-decoupled 15N, 13C, and 1H NMR spectra have been measured. All the signals have been assigned. The 15N NMR chemical shifts in 1-acylated ureas and thioureas are shifted downfield as compared with δ(15N) of urea and thiourea, resp. This shift is greater for N-1 than for N-3 nitrogen atoms in both the series. When comparing acylureas and acylthioureas it is obvious from the Δδ(15N) differences that the CS group is better than CO group in transferring the electron-acceptor effect of acyl group. The proton-coupled 15N NMR spectra of the acylureas dissolved in hexadeuteriodimethyl sulphoxide exhibit a doublet of NH group and a triplet of NH2 group at 25 °C. At the same conditions the acylthioureas exhibit a doublet of NH group, the NH2 group signal being split into a doublet of doublets with different coupling constants 1J(15N, H). The greater one of these coupling constants is due to the s-trans proton with respect to the sulfur atom of the thiourea.

Refinement of labile hydrogen positions based on DFT calculations of 1H NMR chemical shifts: comparison with X-ray and neutron diffraction methods

2017 ◽  
Vol 15 (21) ◽  
pp. 4655-4666 ◽  
Author(s):  
Michael G. Siskos ◽  
M. Iqbal Choudhary ◽  
Ioannis P. Gerothanassis
Keyword(s):  
High Resolution ◽  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Dft Calculations ◽  
Energy Minimization ◽  
Chemical Shifts ◽  
Labile Hydrogen ◽  
X Ray ◽  
Nmr Chemical Shifts ◽  
H Nmr

High resolution structures of hydrogen bonds: experimental (δexp) and GIAO calculated 1H NMR chemical shifts, δcalc, in combination with DFT energy minimization, are an excellent means for obtaining high resolution structures of labile protons.

scholarly journals Cinnamoylphenethylamine 1H-NMR Chemical Shifts: A Concise Reference for Ubiquitous Compounds

2010 ◽  
Vol 5 (8) ◽  
pp. 1934578X1000500 ◽  
Author(s):  
Hans A. Pedersen ◽  
Stine K. Steffensen ◽  
Carsten Christophersen
Keyword(s):  
Natural Products ◽  
1H Nmr ◽  
Spectroscopic Data ◽  
Uv Light ◽  
Chemical Shifts ◽  
Rapid Identification ◽  
Upfield Shift ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Nmr Data

1H-NMR data of 25 cinnamoylphenethylamine derivates were recorded and compared in order to assign signals unequivocally without additional spectroscopic data. The spectra provide a key for the rapid identification of these ubiquitous natural products. The compounds isomerize rapidly in UV light, producing a characteristic upfield shift of the olefinic protons consistent with distorted planarity of the Cis cinnamate, and this requires special attention during preparative work.

scholarly journals Prediction of 1H NMR chemical shifts for ionic liquids: strategy and application of a relative reference standard

RSC Advances ◽  
2018 ◽  
Vol 8 (50) ◽  
pp. 28604-28612 ◽  
Author(s):  
Juanfang Wang ◽  
Ying Liu ◽  
Wen Li ◽  
Guanjun Gao
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
1H Nmr ◽  
Chemical Shifts ◽  
Reference Standard ◽  
Nmr Chemical Shifts ◽  
H Nmr

Using an RRS method to calculate the 1H NMR chemical shifts of ionic liquid agreed well with the experimental value.

1H NMR spectra and the conformation of 1,6 : 2,3- and 1,6 : 3,4-dianhydro-β-D-hexopyranoses and their derivatives

1979 ◽  
Vol 44 (6) ◽  
pp. 1965-1983 ◽  
Author(s):  
Miloš Buděšínský ◽  
Miloslav Černý ◽  
Tomáš Trnka ◽  
Soňa Vašíčková
Keyword(s):  
Hydrogen Bonds ◽  
1H Nmr ◽  
Torsion Angle ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Point Of View ◽  
Coupling Constants ◽  
H Nmr ◽  
Vicinal Coupling Constants ◽  
Intramolecular Hydrogen

The 1H NMR spectra of 1,6 : 2,3- and 1,6 : 3,4-dianhydro-β-D-hexopyranoses and their acetyl-, trichloroacetylcarbamoyl- and 2- or 4-deoxy derivatives were measured in hexadeuteriodimethyl sulfoxide or deuteriochloroform. In these solvents dianhydro derivatives assume the half-chair conformations 5H0 or 1H0 which are not distinctly affected by the presence of substituents. The effects of substituents on the chemical shifts and the adjusted relation for the dependence of the vicinal coupling constants on the torsion angle are discussed from the point of view of conformation and the interactions of the oxirane ring with the oxygen O(5) and O(6) of the 1,6-anhydropyranose skeleton. Intramolecular hydrogen bonds in free dianhydrohexopyranoses were measured and identified in tetrachloromethane solution.

Relativistic and Dynamic effects are needed to correctly model the 1H NMR Chemical Shifts of an Iridium Polyhydride Cluster

2020 ◽  
Author(s):  
Abril C. Castro ◽  
David Balcells ◽  
Michal Repisky ◽  
Trygve Helgaker ◽  
Michele Cascella
Keyword(s):  
1H Nmr ◽  
Chemical Shifts ◽  
Dynamic Effects ◽  
Nmr Chemical Shifts
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