Crystal Structure Determination

To solve a crystal structure means to determine the precise spatial arrangements of all of the atoms in a chemical compound in the crystalline state. This knowledge gives a chemist access to a large range of information, including connectivity, conformation, and accurate bond lengths and angles. In addition, it implies the stoichiometry, the density, the symmetry and the three dimensional packing of the atoms in the solid. Since interatomic distances are in the region of100-300 pm or 1-3 A, 1 microscopy using visible light (wavelength Ä ca. 300-700 nm) is not applicable (Fig. l. l). In 1912, Max von Laue showed that crystals are based on a three dimensionallattice which scatters radiation with a wavelength in the vicinity of interatomic distances, i. e. X -rays with Ä = 50-300 pm. The process bywhich this radiation, without changing its wave­ length, is converted through interference by the lattice to a vast number of observable "reflections" with characteristic directions in space is called X-ray diffraction. The method by which the directions and the intensities of these reflections are measured, and the ordering of the atoms in the crystal deduced from them, is called X-ray struc­ ture analysis. The following chapter deals with the lattice properties of crystals, the starting point for the explanation of these interference phenomena. Interatomic distances Crystals . . . . . . . . . . This textbook gives a concise introduction to modern crystal structure determination, emphasising both its theoretical background and the way it is actually carried out. The theoretical sections are supported by many illustrations, and lay emphasis on a good understanding rather than rigorous mathematics. The most important data collection techniques, and the methods of data reduction, structure solution and refinement are discussed from a practical point of view. Many tips and insights help readers to recognise and avoid possible errors and traps, and to judge the quality of results. The second edition has been considerably updated, especially the chapter on experimental methods, which is now mainly concerned with modern data collection using area-detectors. From the reviews of the first edition: "The book provides a nice balance between describing the mathematical fundamentals and offering practical advice on how to solve a crystal structure ... appropriate for an undergraduate audience (particularly in chemistry) and for graduate students or researchers who find they need a better grasp of the subject ... a very helpful addition to the collection of introductory texts in X-ray crystallography. Especially for its treatment of common errors in the collection of intensity data and in the interpretation of results." Acta Crystallographica This textbook gives a concise introduction to modern crystal structure determination, emphasizing both its theoretical background and the way it is actually carried out. The theoretical sections are supported by many illustrations, and emphasise good understanding rather than rigorous mathematics. The most important data collection techniques, and the methods of data reduction, structure solution and refinement are discussed from a practical point of view. Many tips and insights help readers to recognize and avoid possible errors and traps, and to judge the quality of results. The second edition has been considerably updated, especially the chapter on experimental methods, which is now mainly concerned with modern data collection using area-detectors. From the reviews of the first edition - "Distinguished by its attention to the practicalities of working with real crystals ... a lucid and relatively concise account of modern crystal structure solution ... valuable to anyone who has an interest in crystal structure refinement." The Geological Magazine Front Matter....Pages I-XI Introduction....Pages 1-1 Crystal Lattices....Pages 3-11 The Geometry of X-Ray Diffraction....Pages 13-25 The Reciprocal Lattice....Pages 27-31 Structure Factors....Pages 33-40 Crystal Symmetry....Pages 41-66 Experimental Methods....Pages 67-92 Structure Solution....Pages 93-109 Structure Refinement....Pages 111-125 Additional Topics....Pages 127-143 Errors and Pitfalls....Pages 145-159 Interpretation and Presentation of Results....Pages 161-170 Crystallographic Databases....Pages 171-176 Outline of a Crystal Structure Determination....Pages 177-179 Worked Example of a Structure Determination....Pages 181-197 Back Matter....Pages 199-210 Introduction Crystal Lattices The Geometry of X-Ray Diffraction The Reciprocal Lattice Structure Factors Crystal Symmetry Experimental Methods Structure Solution Structure Refinement Additional Topics Errors and Pitfalls Interpretation and Presentation of Results Crystallographic Databases Outline of a Crystal Structure Determination Worked Example of a Structure Determination Bibliography Index.