Question

Meo 2. The pictured complex was recently Me reported as a tunable catalyst for olefin polymerization. The catalyst is formulated as having the two phosphorus-based ligands trans to each other, the so-called "trans" isomer, - Ph which places the phenyl and O-based sulfonate ligand trans to each other. The alternative "cis" PPh isomer would be one in which the phenyl and the PPh ligand have switched positions, so that the two P-based ligands are cis to each other. Propose an experiment other than X-ray crystallography by which you would be able to distinguish the cis and trans isomers of this novel catalyst.

Answer 1

The Cis and Trans Isomers can be easily seperated by Grinsberg Method.

A bidendate chelating ligand, such as ethylenediamine will form the chelate complex only the cis isomer, thus only 1mole of the en ligand will be consumed to replace the 2 Phosphorus based ligands.

On the other hand, for the trans isomer, no chelate complex will be formed, and thus it will consume 2 moles of the en ligand to substitute 2 Phosphorus based ligands.

Thus, the cis and trans Isomers of the catalyst can be easily seperated.