Advanced search
Start date
Betweenand
(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

The unexpected roles of sigma and pi orbitals in electron donor and acceptor group effects on the C-13 NMR chemical shifts in substituted benzenest

Full text
Author(s):
Viesser, Renan V. ; Ducati, Lucas C. ; Tormena, Claudio F. ; Autschbach, Jochen
Total Authors: 4
Document type: Journal article
Source: CHEMICAL SCIENCE; v. 8, n. 9, p. 6570-6576, SEP 2017.
Web of Science Citations: 13
Abstract

Effects of electron-donating (R = NH2) and electron-withdrawing (R = NO2) groups on C-13 NMR chemical shifts in R-substituted benzene are investigated by molecular orbital analyses. The C-13 shift substituent effect in ortho, meta, and para position is determined by the a bonding orbitals in the aryl ring. The pi orbitals do not explain the substituent effects in the NMR spectrum as conventionally suggested in textbooks. The familiar electron donating and withdrawing effects on the pi system by NH2 and NO2 substituents induce changes in the sigma orbital framework, and the C-13 chemical shifts follow the trends induced in the sigma orbitals. There is an implicit dependence of the a orbital NMR shift contributions on the pi framework, via unoccupied pi{*} orbitals, due to the fact that the nuclear shielding is a response property. (AU)

FAPESP's process: 15/08541-6 - Nuclear magnetic resonance spectroscopy: beyond molecular structure assignment
Grantee:Claudio Francisco Tormena
Support type: Research Projects - Thematic Grants
FAPESP's process: 15/20106-3 - Effects of donating and withdrawing electrons groups on 13C NMR shielding tensor in halo-benzenes derivatives
Grantee:Renan Vidal Viesser
Support type: Scholarships abroad - Research Internship - Doctorate
FAPESP's process: 14/21930-9 - Study of the solvent effect on the spin spin coupling constant 1JPt-Tl in heavy metal complexes by ab initio molecular dynamics
Grantee:Lucas Colucci Ducati
Support type: Scholarships abroad - Research
FAPESP's process: 13/03477-2 - DOSY methods for analyses of the complex mixtures
Grantee:Claudio Francisco Tormena
Support type: Regular Research Grants
FAPESP's process: 12/12414-1 - Relationship between molecular electronic structure and heavy atom effect on 13C NMR chemical shift
Grantee:Renan Vidal Viesser
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 11/17357-3 - Relationship between molecular electronic structure, NMR parameters and conformational stability
Grantee:Claudio Francisco Tormena
Support type: Regular Research Grants