Absolute Configuration and Universal Descriptors

However, once again showing that theories live, develop and die, they do not completely reject the previous system Anticipating this, we shall express the correlation rule , calling it a sequence rule , so that it can be used without change after the concept of standard substance has been discarded. But for the time being, we retain this concept.  

from 1951, Cahn and Ingold, later associated with Prelog, defined a method for attributing absolute configuration based on a simple and universal principle, and we will now detail the application of this principle to organometallic and coordination compounds. In order to describe these compounds two systems are used  

Before reaching the stage of defining absolute configuration, it is appropriate to describe coordination geometry precisely (square planar, tetrahedral, octahedral, etc.) and to define the elements of chirality. 

The priority rules (sequence rule) allow the oriented plane and axis to be dehned, as well as the (R) or (S) character of the conhguration. The priority rules are the same in 

However, in organometallic and coordination chemistry, many other geometric shapes are found besides the tetrahedron. It is possible to extend the rules used above to other polyhedrons. In order to avoid confusion with the tetrahedral systems, the absolute conhgurations will be designated clockwise (C) and anticlockwise (A). 

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