Historical Development of Structural Correlations
The earlier chapter recounted the early history of the development of X-ray crystallography and described how the early technical problems were overcome. It is a fascinating technique because unlike the optical microscope, it required the development of a
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Historical Development of Structural Correlations D. Michael P. Mingos Dedication: This review is dedicated to Professor Alan J Welch of the Chemistry Department, Heriot Watt University, Edinburgh, Scotland, on his retirement. Alan was a research student at Queen Mary College, University of London, in 1971 when I arrived to take up my first academic position. I have always enjoyed my collaborations with him and have admired his research in X-ray crystallography, our joint studies on platinacarboranes, and more recently as an inventive synthetic chemist in the carborane field opening up high nuclearity borane polyhedral molecules.
Contents 1 Introduction 2 Major Advances Derived from Structural Data 2.1 Ionic and Polar Compounds 2.2 Isoelectronic Relationships 3 Quantum Mechanical Description of the Chemical Bond 3.1 Introduction 3.2 Valence Bond Model 3.3 Molecular Orbital Theory 3.4 Ab Initio Calculations 3.5 Natural Bond Orbitals 4 Packing of Molecules in the Solid State 4.1 Introduction 4.2 Space Groups and Packing Densities 4.3 Hydrogen Bonding 4.4 Relationships Between Molecular Shapes and Packing Modes 4.5 Van der Waals’ Radii 4.6 Theoretical Calculations of Crystal Structures 4.7 Crystal Engineering
D. M. P. Mingos (*) Inorganic Chemistry Laboratory, Oxford University, Oxford, UK e-mail: [email protected]
D. M. P. Mingos 5 Structure Correlations in Chemistry 6 Summary References
Abstract The earlier chapter recounted the early history of the development of X-ray crystallography and described how the early technical problems were overcome. It is a fascinating technique because unlike the optical microscope, it required the development of a deeper understanding of the way in which the X-rays interact with the electron density in the planes of the crystal and the development of theories which were able to quantitatively model it. The following sections deal with how the use of these techniques has led to structural chemistry becoming a very important aspect of modern chemistry. In the early days, the structures of even simple organic molecules would take a PhD student several months or even years to solve the structure. Since the 1950s the development of more sophisticated equipment and the massive rise in computing power made it possible to solve the three-dimensional structure of an organic molecule within hours if not minutes. This successful trajectory has resulted in the ability to study ever more complex molecules and use smaller and smaller crystals. The structures of over a million organic and organometallic compounds are now archived in the most commonly used database, and this wealth of information creates a new set of problems for future generations of scientists. This chapter introduces the techniques which have developed to help the chemist use the vast amount of data and the theoretical models which have helped them make use of the data to further their research activities. Keywords Atomic radii · Chemical bonding · Crystal engineering · Hydrogen bonding · Infinite structures · Iso-ele
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