F. Metal Tris Chelates with Non-Planar Ligands that can have &lambda or &delta Ligand Conformations
1. What is a &lambda or a &delta Ligand Conformation? a. &lambda
One isomer of the Co(H2NCH2CH2NH2)33+ ion is shown to your left. More Info / Ref
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Metal Tris Chelates with Non-Planar Ligand Rings can have twists in the 3D-structure of the ligands that give rise to additional stereochemistry
These twists give rise to &lambda or &delta twist ligand conformations. The conformations are defined relative to the plane consisting of the coordinating atom-metal-coordinating atom (in our example, the N-M-N plane that can be highlighed in magneta) for that particular ligand.
What we are looking for is a twist in one of two directions as shown in the schematic below:
To assign the ligand conformation, we need to look down the C2 axis:
Why is it called a &lambda conformation?
Remember that Lambda is associated with Left
and Leftwise Rotations = Counter Clockwise
The &delta ligand conformation is illustrated on the next page