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

Effects of stereoelectronic interactions on the relativistic spin-orbit and paramagnetic components of the C-13 NMR shielding tensors of dihaloethenes

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Viesser, Renan V. [1] ; Ducati, Lucas C. [2] ; Autschbach, Jochen [3] ; Tormena, Claudio F. [1]
Total Authors: 4
[1] Univ Estadual Campinas, Inst Chem, BR-13083970 Campinas, SP - Brazil
[2] Univ Sao Paulo, Inst Chem, BR-05513970 Sao Paulo, SP - Brazil
[3] SUNY Buffalo, Dept Chem, Buffalo, NY 14260 - USA
Total Affiliations: 3
Document type: Journal article
Source: Physical Chemistry Chemical Physics; v. 17, n. 29, p. 19315-19324, 2015.
Web of Science Citations: 8

In this study, stereoelectronic interactions were considered to explain the experimental difference in the magnitude of the known heavy-atom effect on the C-13 NMR chemical shifts in cis- and trans-1,2-dihaloethene isomers (halo = F, Cl, Br or I). The experimental values were compared to the calculated values with various DFT functionals using both the nonrelativistic approach (NR) and the relativistic approximations SR-ZORA (SR) and SO-ZORA (SO). NBO and NLMO contributions to the C-13 NMR shielding tensors were determined to assess which stereoelectronic interactions have a more important effect on the shielding tensor in each principal axis system (PAS) coordinate. These analyses associated with the orbital rotation model and the HOMO-LUMO energy gap enable rationalization of trends between cis and trans isomers from fluorine to iodine derivatives. Both paramagnetic and SO shielding terms were responsible for the observed trends. It was possible to conclude that the steric interactions between the two iodine atoms and the hyperconjugative interactions involving the halogen lone pairs (LP(X)) and pi CQC{*}, sigma CQC{*} and sigma C-X{*} antibonding orbitals are responsible for the lower C-13 NMR shielding for the cis isomers of the bromine and the iodine compounds than that of the trans isomers. (AU)

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: 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: 13/03477-2 - DOSY methods for analyses of the complex mixtures
Grantee:Claudio Francisco Tormena
Support type: Regular Research Grants
FAPESP's process: 10/15765-4 - Transmission Mechanisms Study of Through Space J(FF) Scalar Coupling
Grantee:Lucas Colucci Ducati
Support type: Scholarships in Brazil - Post-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