Complete Prediction of the1H NMR Spectrum of Organic Molecules by DFT Calculations of Chemical Shifts and Spin-Spin Coupling Constants

2001 ◽  
Vol 7 (8) ◽  
pp. 1652-1661 ◽  
Author(s):  
Alessandro Bagno
Keyword(s):  
Dft Calculations ◽  
Organic Molecules ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Nmr Spectrum ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

73 Ge Nuclear Magnetic Resonance Studies

1971 ◽  
Vol 26 (9) ◽  
pp. 1384-1389 ◽  
Author(s):  
J . Kaufmann ◽  
W. Sahm
Keyword(s):  
Chemical Shifts ◽  
Spin Echo ◽  
Relaxation Times ◽  
Least Square ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Nmr Spectrum ◽  
Spin Coupling Constants ◽  
Spin Echo Technique ◽  
Spin Spin Coupling

Abstract The 73Ge spectra of some germanium-tetra-halides, germanium-tetra-alkyles, and of germanium-tetra-methoxide have been observed. The chemical shifts of these 73Ge NMR-lines were measured as functions of the temperature in the range up to 50 °C. In CS2-and benzene-solutions of Gel4 , two 73Ge-lines were found. The 73Ge NMR-spectrum of Ge(CH3)4 caused by indirect spin-spin-coupling between the 73Ge nucleus and the protons is well resolved. The spin-spin-coupling constants of Ge(CH3)4 and of Ge(OCH3)4, which shows an unresolved spectrum, were evaluated by an iterative least square fitting routine. The relaxation times T2 (in the range 30...740 msec) measured by the Carr-Purcell spin-echo-technique and calculated from the line widths are in good agreement. Precision measurements of the ratios of the Larmor frequencies of 73Ge in GeCl4, 41K in aqueous KF-solution and 2H in pure heavy water lead to a magnetic moment of 73Ge: μ = -(0.876 78 ± 0.000 01) μN (uncorrected).

Structural Characterization of Natural Products By Means of Quantum Chemical Calculations of NMR Parameters: New insights

2021 ◽  
Author(s):  
Fabio Luiz Paranhos Costa ◽  
Ana Carolina Ferreira de Albuquerque ◽  
Rodolfo Goetze Fiorot ◽  
Luciano Morais Lião ◽  
Lucas Haidar Martorano ◽  
...  
Keyword(s):  
Natural Products ◽  
Structural Characterization ◽  
Quantum Chemical ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Nmr Parameters ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The calculation of NMR parameters for natural products was pioneered by Bifulco and coworkers in 2002. Since then, modelling 1H and 13C chemical shifts and spin-spin coupling constants for this...

Hyperconjugation In Trialkylboranes Shown By Indirect Nuclear Spin-Spin Coupling Constants. Experimental Data And Density Functional Theory (Dft) Calculations

2005 ◽  
Vol 60 (3) ◽  
pp. 259-264 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Oleg L. Tok
Keyword(s):  
Experimental Data ◽  
Dft Calculations ◽  
Density Functional ◽  
Calculated Data ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Functional Theory ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
C Nmr

Trimethylborane (1), triethylborane (2), 1,3-dimethyl-1-boracyclopentane (3), 1-methyl-1- boracyclohexane (4), 9-methyl- and 9-ethyl-9-borabicyclo[3.1.1]nonane [5(Me) and 5(Et)], and 1- boraadamantane (6) were studied by 11B and 13C NMR spectroscopy with respect to coupling constants 1J(13C,11B) and 1J(13C,13C). Results of DFT calculations at the B3LYP/6-311+g(d,p) level of theory show satisfactory agreement with the experimental data. Hyperconjugation arising from C-C σ bonds adjacent to the tricoordinate boron atom is indicated, in particular for 1-boraadamantane (6), by the optimised calculated structures, and by the experimental and calculated data 1J(13C,13C). The calculated magnitude of 1J(13C,1H) for carbon atoms adjacent to boron becomes significantly smaller if the optimised structures suggest hyperconjugative effects arising from these C-H bonds

The planar conformation of 2-methylthiobenzaldehyde in solution

1983 ◽  
Vol 61 (1) ◽  
pp. 26-28
Author(s):  
Ted Schaefer ◽  
Rudy Sebastian
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spectral Parameters ◽  
H Nmr ◽  
Heavy Atoms ◽  
Planar Conformation ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Infrared Data

The 1H nmr spectral parameters are extracted for a 4 mol% solution of 2-methylthiobenzaldehyde in CCl4 at 305 K. The long-range spin–spin coupling constants involving the aldehydic and methyl protons are consistent only with a preferred conformation in which all heavy atoms are coplanar, as are the chemical shifts of the ring and methyl protons. This conclusion contradicts previous interpretations of the dipole moment, the nmr parameters, and of the infrared data for CCl4 solutions. The present data show that the O-syn and O-anti forms of the compound are present in roughly equal proportions.

A Comparative Study of Metal Shielding in Low Valent Vanadium, Niobium and Manganese Complexes

1982 ◽  
Vol 37 (5) ◽  
pp. 631-645 ◽  
Author(s):  
Dieter Rehder ◽  
Hans-Christoph Bechthold ◽  
Ahmet Keçeci ◽  
Hartwig Schmidt ◽  
Michael Siewing
Keyword(s):  
Comparative Study ◽  
Nuclear Spin ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Manganese Complexes ◽  
Ligand Field ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Ligand Bond

Variations of the metal chemical shifts δ(51V), δ(55Mn) and δ(93Nb) with the paramagnetic deshielding contribution to the overall shielding are discussed in terms of influences imposed by the ligand field splitting, the nephelauxetic effect and the covalency of the metal-to-ligand bond. Complexes under investigation are isoelectronic and/or iso-structural series [M(CO)6-nLn]q (M = V, Nb: q = -1; M = Mn: q = + 1; n = 0-6), η5-C5H5M(CO)4-nLn (M = V, Nb; n = 0-4) and η5-C5H5M(L')2L (M = V, L' = NO; M = Mn, L' = CO). L is a monodentate or l/n oligodentate phosphine. η varies with the point symmetry of the complex, and with ligand parameters of primarily electronic or steric origin. Generally, for weak to medium π-interaction, there is a decrease of shielding with decreasing π-acceptor power of the ligand, increasing ligand bulkiness, increasing ring strains in chelate structures and increasing degree of substitution. For strong π-interaction, the trends may be interconverted. PF3 is shown to be a slightly weaker π-acceptor than CO. Selected results on nuclear-spin spin coupling constants, 13C and 31P shielding are also presented

A Complete Set of NMR Chemical Shifts and Spin−Spin Coupling Constants forl-Alanyl-l-alanine Zwitterion and Analysis of Its Conformational Behavior

2005 ◽  
Vol 127 (48) ◽  
pp. 17079-17089 ◽  
Author(s):  
Petr Bouř ◽  
Miloš Buděšínský ◽  
Vladimír Špirko ◽  
Josef Kapitán ◽  
Jaroslav Šebestík ◽  
...  
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Conformational Behavior ◽  
Nmr Chemical Shifts ◽  
Spin Coupling Constants ◽  
Complete Set ◽  
Spin Spin Coupling
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