"Neutral" and "anionic" carbocations

ORGN 39

Paul v. R. Schleyer, schleyer@chem.uga.edu, Chaitanya S. Wannere, and Zhongfang Chen, chen@chem.uga.edu. Department of Chemistry, Center for Computational Chemistry, University of Georgia, 1004 Cedar St, Athens, GA 30602-2556
Martin Saunders is noted for his pioneering applications of sophisticated dynamic NMR and isotopic labeling methods to study carbocations. The high degree of electron deficiency sets the structures and the behavior of these charged species apart from those of typical organic molecules. Our computations show that neutral and anionic carbocation analogs can exhibit the same basic characteristics (C.S. Wannere, Z. Chen, P. v. R. Schleyer in G. A. Olah, G. K. Surya Prakash, Eds., “Carbocation Chemistry,” Wiley, Hoboken, N.J., 2004). One strategy (“zwitterion”) compensates the positive charge internally by incorporating a negatively charged group at a position remote from the carbocation site. A second strategy is based on the isoelectronic relationship between C+ and B but the boron replaces a carbon away from the carbocation site. A third strategy involves the Lewis-acid complexation of a carbene, derived by deprotonation of a carbocation. Examples illustrating each strategy will be discussed.