Geometric optimization of tetrahedral

WILLIAMSON HALL Geometric Optimizations of Tetrahedral Complexes 19... 

The impact of computer modeling on development in the field is increasing. Databases store all possible tetrahedral frameworks. More detailed analyses allow for the optimization of the host-guest interaction for the synthesis of new materials. Finally, molecular dynamic calculations potentially show the molecular details of the nucleation and crystallization of micropoi-ous crystals. This article lists the most important geometric and crystallographic properties, points out possible applications of microporous silicas, summarizes the recent developments and presents ideas for future progress in the field. 

The Structure module of MOMEC enables you to analyze structures that have been saved as. hin files. These can be structural data files from experimental work, from a data base (e.g. the CSD) or computed structures such as those optimized with MOMEC. The geometric parameters accessible include the calculation of a least-squares plane (defined by three or more points), the distance of atoms from this plane, the angle between a vector such as a metal-ligand bond and a plane, that between two planes, e. g., for the measure of a trigonal twist angle or a tetrahedral twist angle. In this lesson, we will analyze the structures of the four conformers of [Co(en)3]3+ considered in Sections 17.3, 17.4 and 17.5. 

The fact that the molecule has such a distinct geometric form can be explained by the branch of physics known as quantum mechanics. In other words, the tetrahedral configuration of C-H bonds is the consequence of the repulsion of electron pairs which tend to be as far apart as possible from each other. This method of prediction of the molecular shape by considering the optimal distribution of bonds (bonding electron pairs) in which the electron repulsion is minimal, is called VSEPR (valence shell electron pair repulsion). Although this method is widely used, in practice we must point out that this procedure is a simplified approach that can afford only an approximate picture of the molecule. 

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