Modeling NMR Chemical Shifts Downloaded from pubs.acs.org by 93.179.89.90 on 11/29/18. For personal use only.
Preface
In the past fifty years, the N M R Chemical Shielding have evolved from "correc tions to the measurement of nuclear magnetic moments" as quoted from Ramsey's 1950 original papers (Phys. Rev. 77, 567 and 78, 699), to one of the most important tools for structural elucidation in many branches of chemistry. There are no simple relationships between molecular structure and chemical shifts. Their de pendence on the molecular electronic and geometrical structure can be derived via complex quantum mechanical equations. Since the first Symposium on theoretical and physical aspects of the N M R chemical shielding organized in 1992 by Professor Tossel, at a N A T O workshop entitled "Nuclear Magnetic Shielding and Molecular Structure", a number of significant findings, new methodologies, and novel applications have been re ported. In addition, the number of practitioners using N M R chemical shifts to gain information on molecular structure and function has dramatically increased given impetus to the idea of organizing a second meeting in 1998. This volume was developed from the second international symposium on N M R chemical shifts. This meeting was organized by the editors at the 216th National Meeting of the American Chemical Society, Boston, Massachusetts, August 2326,1998, and was cosponsored by the A C S Divisions of Computers in Chemistry and Physical Chemistry. The symposium included four extended lectures by Jameson, Ando, Oldfield, and Nicholas, which are included in this volume as Chapters 1-4, respectively. These lectures provide a convenient review of the current state of the art in the calculation of the N M R chemical shielding (Jameson, Chapter 1), and its application to different areas of chemistry: polymers (Ando), biomolecules (Oldfield), and catalysis (Nicholas). The rest of the papers included in the volume provide a "snap shot" of the field at the time of the symposium. The papers by Ferraro, Sternberg, Schreckenbach, and Webb address new methodologies to calculate N M R chemical shifts. The papers by Kuroki, Kurosu, Sakurai, and Facelli present novel calculations of chemical shifts in molecular systems of biological interest. The contributions by McDermott, Case, and Martin report important advances in the understanding of Ή chemical shifts, and the contribution from de Dios emphasizes the impor tance of the local geometry on the determination of the N M R chemical shifts. The modeling of chemical shifts in inorganic compounds is discussed in detail in the contributions from Buhl, Moore, Wasylishen, Henry, Tossell, Alam, and Jameson (Chapter 23).
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Acknowledgments We thank the contributing authors and the A C S editorial staff for their timely contributions in making this volume a success. Financial support from the A C S Computers in Chemistry Division in supporting the symposium is gratefully ap preciated. JULIO C. FACELLI
Center for High Performance Computing University of Utah 405 I N S C C Salt Lake City, UT 84112 ANGEL C. DE DIOS
Department of Chemistry Georgetown University 37th and Ο Streets, N . W . Washington, DC 20057
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