Experimental and Theoretical Analysis of Vicinal and Long-Range Proton-Proton Coupling Constants for Anthracene Derivatives

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• 作者：Ernesto S&aacute ; nchez-Mendoza ; Jesú ; s Hern&aacute ; ndez-Trujillo ; Federico del Rí ; o-Portilla
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：August 23, 2007
• 年：2007
• 卷：111
• 期：33
• 页码：8264 - 8270
• 全文大小：179K
• 年卷期：v.111,no.33(August 23, 2007)
• ISSN：1520-5215

文摘

We studied vicinal and long-range coupling constants for 9-anthracene derivatives, e.g., Br, CN, CHO, NO<SUB>2,CH₂Cl, CH₂OH, and OCH₃. We performed the accurate measurements using modified J doubling in thefrequency domain, even for the smallest couplings immersed within the line width. Density functional theoryallowed us to reproduce and exhaustively analyze the physical contributions to the values of these spectroscopicparameters. The theory of atoms in molecules defines a delocalization index that correlates linearly withvicinal and long-range coupling constants when they are grouped in terms of the number of bonds betweenthe coupled nuclei. An exception to this behavior is obtained for ⁴J_H4,H10 values, which have a negative Fermicontact and the largest delocalization index for each molecule. This observation can be explained by acharacteristic "gable roof" arrangement formed by the five nuclei involved in the coupling.