C-3. Assigning the Absolute Configuration (Λ or Δ)
b. Method 2: Viewed as a Screw, i) The Δ Isomer
Illustrated using Δ-tris(acetonylacetonate)chromium(III)1. Align your molecule so that you
2. Look at the set of three atoms in front as creating a triangular face and the set of atoms in back as creating an triangular face
Potentially useful viewing tools:
3. Think of the front face (with red atoms) as the head of a screw
and the back face (with green atoms) as the biting edge of the screw.
The threads of the screw are the ligand backbones.
Now determine which way you must rotate the screw for it to bite into the back surface.
This is the Delta (Δ) Isomer: You must to make the ligands (threads of the screw) bite into the back surface.