1. Experimental and Theoretical Analysis of Vicinal and Long-Range Proton−Proton Coupling Constants for Anthracene Derivatives.
- Author
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Ernesto Sánchez-Mendoza, Jesús Hernández-Trujillo, and Federico del Río-Portilla
- Subjects
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PARTICLES (Nuclear physics) , *ANTHRACENE , *POLYCYCLIC aromatic hydrocarbons , *DENSITY functionals - Abstract
We studied vicinal and long-range coupling constants for 9-anthracene derivatives, e.g., Br, CN, CHO, NO2, CH2Cl, CH2OH, and OCH3. We performed the accurate measurements using modified Jdoubling in the frequency domain, even for the smallest couplings immersed within the line width. Density functional theory allowed us to reproduce and exhaustively analyze the physical contributions to the values of these spectroscopic parameters. The theory of atoms in molecules defines a delocalization index that correlates linearly with vicinal and long-range coupling constants when they are grouped in terms of the number of bonds between the coupled nuclei. An exception to this behavior is obtained for 4JH4,H10values, which have a negative Fermi contact and the largest delocalization index for each molecule. This observation can be explained by a characteristic “gable roof” arrangement formed by the five nuclei involved in the coupling. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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