Titlebook: Crystal Structure Determination; Werner Massa Textbook 20001st edition Springer-Verlag Berlin Heidelberg 2000 Kristall.Kristallographie.Pu

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The following summary gives an overview of the steps in an X-ray structure deter­mination, together with the chapters and sections in which a more detailed account may be found.

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In this chapter, the most important stages in a structure determination will be given using as an example the thiourea adduct of N-salicylideneglycinatocopper(II) Cu(sg)SC(NH.)., (“CUHABS,” molecular formula C.H.N.O.SCu, C. Friebel, Marburg: cf. Fig. 12.5–12.7). Computer output is given in an abbreviated form and commentated in italic.

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Experimental Methods,This chapter deals with the most important methods for obtaining the necessary data for an X-ray single crystal structure determination. The first step, naturally, is the obtaining of a suitable crystal.

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Structure Solution,The direct results of the experimental measurements for a crystal structure are: the unit cell parameters, the space group (or at least a small selection of possibilities) and the intensity data. The real purpose of the work, however, remains — the location of the atoms in the unit cell.

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Interpretation and Presentation of Results,Despite all the possible pitfalls and errors described in the last chapter, crystal structures usually arrive at the point where the refined model is ready to be converted into structural parameters of interest to chemists.

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Crystallographic Databases,The results of crystal structure determinations form the basis of several large databases, which are accessible in most countries of the world through local organisations. Three of these contain most of the data of interest to chemical crys­tallographers. They may be accessed at national centers, and they are available on CD-ROM.

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Worked Example of a Structure Determination,In this chapter, the most important stages in a structure determination will be given using as an example the thiourea adduct of N-salicylideneglycinatocopper(II) Cu(sg)SC(NH.)., (“CUHABS,” molecular formula C.H.N.O.SCu, C. Friebel, Marburg: cf. Fig. 12.5–12.7). Computer output is given in an abbreviated form and commentated in italic.

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Third Parties and Exploitation,o how the various intensities associated with the reflections . arise. It will then become clear how the measurement of the intensities of a large number of reflections can reveal the arrangement of atoms in the unit cell.