title: Conformational and NMR study of some furan derivatives by DFT methods.
abstract: 4'-substituted neutral/protonated furfurylidenanilines and trans-styrylfurans are able to exist in two different conformations related to the rotation around the furan ring-bridge double bond. In this work, the equilibrium geometry and the corresponding rotational barrier of the benzene ring for each furan derivative conformation were calculated by DFT methods. The trend and shape of the rotational barrier are rationalized within natural bond orbitals as well as atoms-in-molecules approach. For the corresponding equilibrium geometries, (1)H and (13)C substituent induced shifts (SIS) were calculated and compared with experimental values. Calculated shielding constants are shown to be sensitive to the substituent effect through a linear fit with substituent's Hammett constants. An alternative approach was followed for assessing the effect of substituents over SIS through comparing the differences in isotropic shielding constants with NBO charges as well as with (1)H and (13)C experimental chemical shifts.
authors: Departamento de Química Física, Facultad de Química, Universidad de La Habana, Ciudad de La Habana, Cuba.
authors: David
authors: D
authors: Santos-Carballal
authors: Reynier
authors: R
authors: Suardíaz
authors: Rachel
authors: R
authors: Crespo-Otero
authors: Leandro
authors: L
authors: González
authors: Carlos S
authors: CS
authors: Pérez
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