Advances in X-Ray Crystallography Since

Advances in interpretation. Experimental KIEs are interpreted using quantum mechanical and/or bond order vibrational analysis (BOVA) approaches to yield the experimental transition state. In systems that are well understood, the accuracy of experimental TS structures derived using a BOVA unified model rivals X-ray crystallography of stable molecules. The largest advance in KIE interpretation since the description of BOVA by Sims and Lewis " has been the increase in computational power available to the average chemist. Previously, vibrational models were reduced to a minimal number of atoms to make them computationally tractable. Today, a desktop computer can perform BOVA calculations with hundreds of atoms. The accessibility of post-Hartree-Fock calculations to the average chemist has made ab initio calculations a routine part of TS analysis, and made possible the structure interpolation approach to BOVA. 

There are numerous crystal structures of substitutionally inert Cr(III) complexes [e.g., (80)] and, if suitable crystals can be grown. X-ray crystallography is the method of choice for characterizing Cr(III) complexes. However, the structural characterization of Cr(III) complexes with biomolecules has been rather elusive and there have not been many advances in this area since the early work by Freeman and co-workers [(81-84) and references cited therein] on Cr(lll) amino acid and peptide complexes. Some of the Cr(lll) dietary supplements have also been characterized by X-ray crystallography (Section IV.D), but none of the species generated in vivo or present in the diet have been structurally characterized. 

In 1994, the first edition of this book was published. Since then there have been several almost revolutionary advances in the technology of x-ray crystallography. Among them are the x-ray source, new instruments and faster computer programs. The accomplishments of the Human Genome Project pushes a vigorous pursuit for the determination of the structures of both nucleic acid and proteins. X-ray crystallography is the number 1 tool, followed by NMR. 

Crystallography is an advanced discipline [318], Modern crystallography has been developed since the discovery of X-ray diffraction in 1912 from the original basis laid down by classical crystallographers. One of the beauties of this modern discipline, while it can be somewhat mathematical, is the universal use of standardised notations and conventions, as developed through the International Union of Crystallography (IUCr). 

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