Pi-Electron Delocatlization in Organic Molecules with C-N Bonds   

Vernon G. S. Box and Hing Wan Yu

The City College, Department of Chemistry, The City University of New York, Convent Avenue at 138th Street, New York, NY 10031    

Abstract

Molecular modeling can provide great stimulation to the pedagogical process if students and teachers use this tool to examine the structural aspects of organic molecules whose structures have been determined by X-ray crystallography. An example of this is provided by one of our undergraduate research projects that examined delocalization in p-systems. The experimentally determined X-ray crystallographic coordinate data of molecules that possess conjugated p-systems provide bond length data that can unequivocally confirm, or deny, the existence of delocalized p-electrons in these p-systems. The presence of delocalized p-electrons in the ground state of a molecule that possesses a conjugated p-system is normally assumed, particularly if theoretical calculations on analogous systems support this premise. However, there are many instances in which this bond length analysis proves the theoretical predictions to be erroneous.

Journal of Chemical Education, 1997, 74, 1293            Full text (PDF)

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