Solid state structure, theory

Thus, solution and solid-state structural studies of such fluoroolefin compounds have helped to formulate and refine theories of metal-carbon bonding. Studies of the reactivity of metal-fluoroolefin compounds have also provided useful models and predictions for hydrocarbon systems. For example, the oxidative cyclization of fluoroolefins within the coordination sphere of a metal to give metallacyclopentane compounds was discovered many years before the importance of the corresponding reaction of hydrocarbon olefins was realized (3). 

The structures of the element trihalides EX3 are covered in a number of textbooks on structural inorganic chemistry (4, 5), and these will not be discussed in great detail here. It is, however, worth mentioning some of the salient structural features. In most cases, a molecular trigonal pyramidal EX3 unit consistent with VSEPR theory predictions is readily apparent in the solid-state structure, although there are usually a number of fairly short intermolecular contacts or secondary bonds present. A general description of the structures as molecularly covalent but as having a tendency toward macromolecular or polymeric networks is therefore reasonable. Only in the case of the fluorides is an ionic model appropriate. 

Band theory should be treated with some caution. The presence of bands in solid state structures is well supported by X-ray emission and absorption data where energy is emitted (or absorbed) over a range relating to the band structure. However, even in this simple case, band theory fails to explain why MnO is insulating. In the argument used above, MnO has electron vacancies in the t2g and should be conducting. 

Hoffmann s integration of molecular orbital theory and symmetry have influenced the way chemists think of molecules, their spectroscopic properties and reactions and the properties of solid-state structures since the mid-1960s. But he has also been an example and a role model for young scientists. While distinguished university... 

VSEPR theory and ligand field theory show the great effect of electrostatic repulsion of the electrons in a molecular complex, but similar influences can also be expected at the formation of solid-state structures. 

This chapter is dedicated to fundament the crystallographic approach of the solid state structure and properties by presenting the main features the geometric as well the d5mamical theory of X-ray diffractions may reveal for a perfect crystal. Here will be studied their fields and intensities, the equations that cormect them as also the solutions of propagation for the non-absorbent or respectively absorbent crystals the present discussion follows Putz and Lacrama (2005). 

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