With the support of the Organic Dynamics Program and the Office of Multidisciplinary Activities of the Mathematical and Physical Sciences Directorate, Professor Kenneth B. Wiberg, of the Department of Chemistry at Yale University, studies the factors that control the properties, reactions, and reactivity of organic molecules. Through a combination of experimental and theoretical approaches, Professor Wiberg addresses the degree of structural distortion possible in small-ring compounds and the changes in energy and other properties that result from such distortion. Carbon-bridged spiropentanes are expected to have a remarkably high degree of ring distortion, with theory suggesting the presence of a nearly linear bond angle at the central carbon. Theoretical and structural studies of related spiropentyl cations address the factors controlling the two different types of rearrangements observed for these systems. Questions related to the structure and stability of small-ring cycloalkynes and the attack by methylene and by permanganate on carbon-carbon double bonds are also targeted for synthetic and theoretical analysis. Professor Wiberg also explores the magnitude and the origin of the equatorial conformational preference in monosubstituted cyclohexanes, focusing on careful analysis of the conformational preference of the methyl group and on the role of entropy terms in determining conformational preferences. Theories regarding the structure and reactivity of organic molecules continue to be tested experimentally, through the preparation of molecules designed to probe the limits of chemical bonding, and theoretically, through the calculational analysis of bonding issues in such molecules. Professor Kenneth B. Wiberg, of the Department of Chemistry at Yale University, with the support of the Organic Dynamics Program and the Office of Multidisciplinary Activities of the Mathematical and Physical Sciences Directorate, explores molecules known or expected to display extreme structural distortions. These studies target a number of classes of molecules, particularly those in which bond angles at carbon atoms forming part of a small ring are forced to deviate markedly from their preferred values in the absence of the geometry enforced by these small rings. Through these studies, Professor Wiberg gains fundamental knowledge regarding the factors that control the properties, reactions, and reactivity of organic molecules.
