Chiral metal complexes notation

Because many chelate rings are not planar, they can have different conformations in different molecules, even in otherwise identical molecules. In some cases, these different conformations are also chiral. The notation used also requires using two lines to establish the handedness and the lower case labels X and 8. The first line connects the atoms bonded to the metal. In the case of ethylenediamine, this line connects the two nitrogen atoms. The second line connects the two carbon atoms of the ethylenediamine, and the handedness of the two rings is found by the method described in Section 9-3-5 for separate rings. A counterclockwise rotation of the second line is called X (lambda) and a clockwise rotation is called 8 (delta), as shown in Figure 9-16. Complete description of a complex then requires identification of the overall chirality and the chirality of each ring. 

The asymmetric cluster in Figure 16 is representative of the structures in which the chirality properties of the structure are not associated with any atomic site in the molecule. Metalloborane clusters with this type of symmetry properties have also been reported. The stereochemical notation for asymmetric clusters will have to specify cluster chirality. And when clusters with more complex ligand substitution patterns and chiral ligands are prepared, the configurations of all metal centers and the chiralities of the associated ligands must be given. 

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