Isomerization effects on chemical shifts and spin-spin coupling constants of polyacetylene chains: A GIAO-DFT study

2011 ◽  
Vol 111 (7-8) ◽  
pp. 1616-1625 ◽  
Author(s):  
G. Colherinhas ◽  
T. L. Fonseca ◽  
H. C. Georg ◽  
M. A. Castro
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Dft Study ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

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...

Lone-Pair Orientation Effect of an α-Oxygen Atom on 1JCC NMR Spin−Spin Coupling Constants in o-Substituted Phenols. Experimental and DFT Study

2007 ◽  
Vol 3 (4) ◽  
pp. 1284-1294 ◽  
Author(s):  
Oscar E. Taurian ◽  
Rubén H. Contreras ◽  
Dora G. De Kowalewski ◽  
Jorge E. Pérez ◽  
Cláudio F. Tormena
Keyword(s):  
Oxygen Atom ◽  
Lone Pair ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Dft Study ◽  
Orientation Effect ◽  
Substituted Phenols ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

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

Relation between the carbon chemical shifts and theJ(CH) spin-spin coupling constants

1973 ◽  
Vol 5 (7) ◽  
pp. 351-352 ◽  
Author(s):  
T. Pehk ◽  
M. Alla ◽  
E. Lippmaa
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

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

Influence of solvents on the chemical shifts and spin - spin coupling constants of protons in alkaloids I. Haplophyllidine

1973 ◽  
Vol 9 (4) ◽  
pp. 477-480
Author(s):  
K. L. Seitanidi ◽  
M. R. Yagudaev ◽  
S. Yu. Yunusov
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Influence Of Solvents
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