Effects of donating and withdrawing electrons groups on 13C NMR shielding tensor in halo-benzenes derivatives

• Grant number: 15/20106-3
• Support type: Scholarships abroad - Research Internship - Doctorate
• Effective date (Start): December 14, 2015
• Effective date (End): December 08, 2016
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Organic Chemistry
• Principal researcher: Claudio Francisco Tormena
• Grantee: Renan Vidal Viesser
• Supervisor abroad: Jochen Autschbach
• Home Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Research place: State University of New York, Buffalo State (SUNY), United States
• Associated to the scholarship: 12/12414-1 - Relationship between molecular electronic structure and heavy atom effect on 13C NMR chemical shift, BP.DR

Abstract

Stereoelectronic interactions are commonly required to explain the stability of different compounds or the reactivity of some substrates. Moreover, these interactions are important to understand the effects of electron-donating and electron-withdrawing groups in aromatic systems, mainly related to resonance effects. Despite of these known interactions, the effect of some groups (e.g. nitro and amine) in dissubstituted systems are not completely understood especially in ortho orientation. Stereoelectronic interactions have been studied in our group by NMR parameters, dealing mainly on how these interactions affect the magnitude of the heavy-atom effect on the 13C NMR chemical shifts. Experimental values of 13C NMR chemical shifts, related to the iodonitrobenzene isomers (ortho, meta and para) and iodoaniline isomers, showed intriguing differences. Therefore, the target of this project is to investigate which components of 13C shielding tensor are responsible for the experimental differences of chemical shifts found between three isomers (ortho, meta and para) of the iodonitrobenzene and iodoaminobenzene. The NBO and NLMO contributions to the 13C NMR shielding tensor, as well as, the orbital rotation model and HOMO-LUMO energy gap study are proposed to be used to rationalize the trends of shielding tensor. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

VIESSER, RENAN V.; DUCATI, LUCAS C.; TORMENA, CLAUDIO F.; AUTSCHBACH, JOCHEN. The halogen effect on the C-13 NMR chemical shift in substituted benzenes. Physical Chemistry Chemical Physics, v. 20, n. 16, p. 11247-11259, APR 28 2018. Web of Science Citations: 9.

VIESSER, RENAN V.; DUCATI, LUCAS C.; TORMENA, CLAUDIO F.; AUTSCHBACH, JOCHEN. 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. CHEMICAL SCIENCE, v. 8, n. 9, p. 6570-6576, SEP 2017. Web of Science Citations: 13.

VIESSER, RENAN V.; DUCATI, LUCAS C.; AUTSCHBACH, JOCHEN; TORMENA, CLAUDIO F. NMR spin-spin coupling constants: bond angle dependence of the sign and magnitude of the vicinal (3)J(HF) coupling. Physical Chemistry Chemical Physics, v. 18, n. 34, p. 24119-24128, SEP 14 2016. Web of Science Citations: 4.