A guide to analyzing the structures and properties of organic molecules 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 Authored by a founding father of computational chemistry, Molecular Structure broadens the scope of the subject by serving as a pioneering guide for workers in the fields of organic, biological, and computational chemistry, as they explore new possibilities to advance their discoveries. This work will also be of interest to many of those in tangential or dependent fields, including medicinal and pharmaceutical chemistry and pharmacology.

A guide to analyzing the structures and properties of organicmoleculesUntil recently, the study of organic molecules has traveled downtwo disparate intellectual paths--the experimental, orphysical, method and the computational, or theoretical, method.Working somewhat independently of each other, these disciplineshave guided research for decades, but they are now being combinedefficiently into one unified strategy.Molecular Structure delivers the essential fundamentalson both the experimental and computational methods, then goesfurther to show how these approaches can join forces to producemore effective analysis of the structure and properties of organiccompounds by:* Looking at experimental structures: electron, neutron, X-raydiffraction, and microwave spectroscopy as well as computationalstructures: ab initio, semi-empirical molecular orbital, andmolecular mechanics calculations* Discussing various electronic effects, particularlystereoelectronic effects, including hyperconjugation, negativehyperconjugation, the Bohlmann and anomeric effects, and how andwhy these cause changes in structures and properties ofmolecules* Illustrating complex carbohydrate effects such as the gaucheeffect, the delta-two effect, and the external anomeric torsionaleffect* Covering hydrogen bonding, the CH bond, and how energiesespecially heats of formation, can be affected* Using molecular mechanics to tie all of these things togetherin the familiar language of the organic chemist, valence bondpicturesAuthored by a founding father of computational chemistryMolecular Structure broadens the scope of the subject byserving as a pioneering guide for workers in the fields of organicbiological, and computational chemistry, as they explore newpossibilities to advance their discoveries. This work will also beof interest to many of those in tangential or dependent fieldsincluding medicinal and pharmaceutical chemistry andpharmacology.

Preface.Chapter 1 Introduction.What, Exactly, is a Molecular Structure?References.Chapter 2 Experimental Molecular Structure.Electron Diffraction.Microwave Spectroscopy.X-Ray Crystallography.Neutron Diffraction.But Bond Lengths Depend Upon the Method Used to Determine Them?References.Chapter 3 Molecular Structures by Computational Methods.A Brief History of Computers.Computational Methods.Semi-Empirical Quantum Mechanical Methods.Ab Initio Methods.Molecular Mechanics.References.Chapter 4 Molecular Mechanics of Alkanes.The Potential Energy Surface.The Force Constant Matrix.The Diagonal Part.The Off-Diagonal Part.Stretch-Bend Effect.Urey-Bradley Force Field.Bend-Torsion-Bend Interactions.References.Chapter 5 Conjugated Systems.General.Structures of Conjugated Hydrocarbons.Structures of Conjugated Heterocycles.References.Chapter 6 "Effects" in Organic Chemistry.The Electronegativity Effect.Electronegativity Effect on Bond Lengths.Electronegativity Effect on Bond Angles.Hyperconjugation.The Baker-Nathan Effect.References.Chapter 7 Negative Hyperconjugation.The Bohlmann Effect.The Anomeric Effect.Dimethoxymethane.References.Chapter 8 Stereochemistry of Carbohydrates.The Gauche Effect.The Delta-Two Effect.The External-Anomeric Torsional Effect.References.Chapter 9 Lewis Bonds.Hydrogen Bonds.The Directional Dependent Hydrogen Bond.The C-H Hydrogen Bond.Other Lewis Bonds.References.Chapter 10 Crystal Structure Calculations.The Crystalline Phase.The Benzene Crystal.References.Chapter 11 Heats of Formation.References.Appendix.The Driver Routine.Conformational Search.References.References.