Benzylic coupling constants in toluene derivatives by J doubling in the frequency domain and DFT calculations.
The recently modified J doubling in the frequency domain method (MJDFDM) allowed the determination of (4, 5, 6)J(H, CH(3) ) in toluene, a series of 4-mono- and 3,5-disubstituted toluene derivatives, as well as in 4-picoline. The methyl and aromatic signals were subjected to successive deconvolution processes, which at the end led to singlet signals and afforded the corresponding coupling constant values with a high degree of accuracy. Density functional theory calculation of benzylic coupling constants by addition of the Fermi contact, the spin-dipole, the diamagnetic spin-orbit, and the paramagnetic spin-orbit terms revealed good agreement between predicted and measured values when the B3LYP/aug-cc-pVTZ level of theory was used. Evaluation of the substituent effect over the coupling constant was made for all studied compounds and some limitations of the methodology were evidenced.
Pérez-Hernández
Nury
N
Escuela de Medicina, Universidad Autónoma del Estado de Hidalgo, Apartado 1-622, Pachuca, Hidalgo 42001, México.
Alvarez-Cisneros
Celina
C
Cerda-García-Rojas
Carlos M
CM
Morales-Ríos
Martha S
MS
Joseph-Nathan
Pedro
P
D000465:Algorithms; D003627:Data Interpretation, Statistical; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D014050:Toluene / Q000031:analogs & derivatives* / Q000737:chemistry*
D014050:Toluene