Molecular Structure: Understanding Steric and Electronic Effects from molecular mechanics Norman L. Allinger Until recently, the study of organic molecules has traveled down two disparate intellectual paths - the experimental, or physical, method and the computational, or theoretical, method. Working somewhat independently of each other, these disciplines have guided research for decades, but they are now being combined efficiently into one unified strategy. Molecular Structure delivers the essential fundamentals on both the experimental and computational methods, then goes further to show how these approaches can join forces to produce more effective analysis of the structure and properties of organic compounds by: • Looking at experimental structures: electron, neutron, X-ray diffraction, and microwave spectroscopy as well as computational structures: ab initio, semi-empirical molecular orbital, and molecular mechanics calculations • Discussing various electronic effects, particularly stereoelectronic effects, including hyperconjugation, negative hyperconjugation, the Bohlmann and anomeric effects, and how and why these cause changes in structures and properties of molecules • Illustrating complex carbohydrate effects such as the gauche effect, the delta-two effect, and the external anomeric torsional effect • Covering hydrogen bonding, the CH bond, and how energies, especially heats of formation, can be affected • Using molecular mechanics to tie all of these things together in the familiar language of the organic chemist, valence bond pictures [...] Norman L Allinger received his BS from the University of California, Berkeley, in 1951 and his PhD from the University of California, Los Angeles, in 1954. He was on the faculty at Wayne State University before coming to the University of Georgia as Research Professor in 1969. He is known for his use of computational chemistry, especially molecular mechanics, to solve a variety of chemical problems. He is the senior author of the MM2, MM3, and MM4 molecular mechanics software packages.