Methods in structural chemistry

Nuclear magnetic resonance (NMR) has developed into one of the most powerful methods in structural chemistry for the study of organic molecules in solution. An important component of the information contained in NMR spectra resides in... 

The use of computational methods in structural chemistry has changed focus in recent years, with less emphasis on the determination of absolute structure and greater emphasis on the application of these methods to explain topics such as conformation, tautomerism, and the source of any preferences for given forms. This change dominates the section below though the computations of some simple structures have been carried out. 

F. Woodbye and G. Borch, Some New Physical Methods in Structural Chemistry , ed. R. Bonnet and J. G. Davies, United Trade Press, London, 1967. 

Details of bond lengths and bond angles for all the X-ray structures of heterocyclic compounds through 1970 are listed in Physical Methods in Heterocyclic Chemistry , volume 5. This compilation contains many examples for five-membered rings containing two heteroatoms, particularly pyrazoles, imidazoles, Isoxazoles, oxazoles, isothlazoles, thlazoles, 1,2-dlthloles and 1,3-dlthloles. Further examples of more recent measurements on these heterocyclic compounds can be found in the monograph chapters. 

Theoretical and structural studies have been briefly reviewed as late as 1979 (79AHC(25)147) (discussed were the aromaticity, basicity, thermodynamic properties, molecular dimensions and tautomeric properties ) and also in the early 1960s (63ahC(2)365, 62hC(17)1, p. 117). Significant new data have not been added but refinements in the data have been recorded. Tables on electron density, density, refractive indexes, molar refractivity, surface data and dissociation constants of isoxazole and its derivatives have been compiled (62HC(17)l,p. 177). Short reviews on all aspects of the physical properties as applied to isoxazoles have appeared in the series Physical Methods in Heterocyclic Chemistry (1963-1976, vols. 1-6). 

Periodic acid oxidation (Section 15.12) finds extensive use as an analytical method in carbohydrate chemistry. Structural information is obtained by measuring the number of equivalents of periodic acid that react with a given compound and by identifying the reaction products. A vicinal diol consumes one equivalent of per-iodate and is cleaved to two carbonyl compounds ... 

The most important experimental task in structural chemistry is the structure determination. It is mainly performed by X-ray diffraction from single crystals further methods include X-ray diffraction from crystalline powders and neutron diffraction from single crystals and powders. Structure determination is the analytical aspect of structural chemistry the usual result is a static model. The elucidation of the spatial rearrangements of atoms during a chemical reaction is much less accessible experimentally. Reaction mechanisms deal with this aspect of structural chemistry in the chemistry of molecules. Topotaxy is concerned with chemical processes in solids, in which structural relations exist between the orientation of educts and products. Neither dynamic aspects of this kind are subjects of this book, nor the experimental methods for the preparation of solids, to grow crystals or to determine structures. 

The potential value of the application of molecular orbital methods in colour chemistry is immense. In essence, the reason for this is that the methods enable, in principle, many of the light absorption properties of dyes, from a knowledge of their chemical structure, to be calculated with the aid of a computer. Thus, the colour properties of any dye whose structure may be drawn on paper may be predicted, with some expectation of accuracy, without the need to resort to devising a method for the... 

E. A. V. Ebsworth, D. W. H. Rankin, and S. Cradock, Structural Methods in Inorganic Chemistry, 1987, Blackwell, Edinburgh. 

Since x-ray crystallography provides a visualization of a molecular image, it is difficult to overestimate its role in structural chemistry. For this reason, x-ray diffraction continues to be the method of choice for structural investigations of molecules and molecular assemblies containing hydrogen or dihydrogen bonds. 

B. O. Roos. The complete active space self-consistent field method and its apphca-tion in electronic structure calculations. In K. P. Lawley, editor, Ab Initio Methods in Quantum Chemistry. Part II, volume 69 of Adv. Chem. Phys., pages 399-446. John Wiley, Chichester, 1987. 

Ebsworth, E.A.V., Rankin, D.W.H., and Cradock, S. (1991) Structural Methods in Inorganic Chemistry, 2nd edn, Blackwell Scientific Publications, Oxford. 

Sedoi, V.S., and Valevish, V.V. (1999) Direct production of nano sized powders by the exploding wire method, in Physics, Chemistry and Applications of Nano Structures (Nanomeeting-99) (eds. V.E. Borisenko, A.B. Filonov, S.V. Gaponenko and V.S. Gurin.), World Scientific Publishing Company, New Jersey, USA, p. 322. 

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