Chemical Anticooperativity and Sigma-Pi Hybridization

Abstract

In every scientific discipline, the accumulated knowledge regarding the structure of fundamental entities raises the question of their interaction. Thus, in zoology, we inquire as to how bone and tissue are connected (i.e., interact) so that their combined actions can produce motion. In molecular biology, we inquire as to how an enzyme and an effector molecule combine (i.e., interact) in order to produce a complex which is catalytically active, or, inactive. Finally, reaching further down to the foundation of physical reality, one can inquire as to how bonds interact within molecules in order to produce the lowest possible energetic state. Now, one of the difficulties which thwart studies of the latter type is the mere fact that, in order to investigate interaction, one must be able to define the interacting elements. This is not a problem in, e.g., zoology, where we can unequivocally define bone, tissue, etc., but, it does constitute a problem in quantum chemistry because clear definitions of “non-interacting bonds” and “after-interaction-bonds” are possible within the framework of one but not of another theoretical approach. That is to say, one must appropriately choose among different theoretical vehicles before undertaking a study of interaction at the electronic level since the construct of “bond” is only a model-dependent construct. The purpose of this paper is to exploit the formal and conceptual advantages of Valence Bond (VB) theory¹ in order to provide a blueprint for the study of interaction at the electronic level through formulation and illustrative application of concepts that may ultimately lead to a good understanding of electronic control mechanisms within atoms and molecules.