13C NMR: nJCH and 1JCC scalar spin–spin coupling constants (SSCCs) for some 3-monosubstituted 2-methylpropenes

Autor: Ivânia T.A. Schuquel, Roberto Rittner, Matheus P. Freitas, Lucas C. Ducati, Cláudio F. Tormena, Dora G. de Kowalewski

Publikováno v: Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual)
Universidade de São Paulo (USP)
instacron:USP

Twelve methallylic derivatives were studied using 13C NMR spectroscopy and theoretical calculations. Theoretical coupling constants were obtained with SOPPA (CCSD). All atoms were described by the EPR-III basis set, except for halogens, which were re

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::8316e741be20048da512c053ef752bc8
https://doi.org/10.1016/j.molstruc.2014.04.008

NMR J(13C,13C) spin–spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies

Autor: Jorge E. Pérez, Dora G. de Kowalewski, Oscar E. Taurian, Rubén H. Contreras

Publikováno v: Journal of Molecular Structure. 754:1-9

J ( 13 C, 13 C) spin–spin couplings were measured at natural abundance in five pyridine aldehyde derivatives. Such couplings were also calculated at the DFT-B3LYP-6-311G**/EPR-III level of theory where special attention was paid to their possible s

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::a307d37e378970430c0fafa9a524cd96
https://doi.org/10.1016/j.molstruc.2005.06.002

Substituent effects on scalarJ(13C,13C) couplings in pyrimidines. An experimental and DFT study

Autor: Ernesto Díez, Juan E. Peralta, Veronica Barone, Dora G. de Kowalewski, Rubén H. Contreras, Angel L. Esteban

Publikováno v: Magnetic Resonance in Chemistry. 42:938-943

One- two- and three 13C, 13C (n = 1, 2, 3) scalar couplings, nJ(C,C) in a set of pyrimidine derivatives were studied both experimentally at natural abundance and theoretically by their DFT calculation of all four contributions. Trends of non-contact

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::b015d22861879699e4904659d5324567
https://doi.org/10.1002/mrc.1426

Conformational effects on13C NMR parameters in alkyl formates

Autor: Valdemar J. Kowalewski, Angel L. Esteban, Rubén H. Contreras, Ernesto Díez, Dora G. de Kowalewski

Publikováno v: Magnetic Resonance in Chemistry. 36:336-342

The 13C NMR spectra of a series of alkyl formates which show the coexistence of s-cis and s-trans rotamers at room temperature were measured at 125 MHz. 13C chemical shifts and 1J(CH) couplings are compared for both types of rotamers. Their differenc

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::f78bd42dba2a5890d55aa5cba1de9b95
https://doi.org/10.1002/(sici)1097-458x(199805)36:5<336::aid-omr273>3.0.co

Solvent Effects on Oxygen-17 Chemical Shifts in Amides. Quantitative Linear Solvation Shift Relationships

Autor: Ioannis P. Gerothanassis, Jesús San Fabián, Angel L. Esteban, José-Luis M. Abboud, Dora G. de Kowalewski, Ernesto Díez, Rubén H. Contreras

Publikováno v: Journal of Magnetic Resonance. 124:8-19

A multiple-linear-regression analysis (MLRA) has been carried out using the Kamlet–Abboud–Taft (KAT) solvatochromic parameters in order to elucidate and quantify the solvent effects on the 17 O chemical shifts of N -methylformamide (NMF), N , N -

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::c2ab04424d4ea4c414d2e12cff72e8eb
https://doi.org/10.1006/jmre.1996.7481