[celtic07]

- What is the general method of separating two optical isomers in a metal complex?

I know this is probably a chromatographic method but it would help me a lot if someone could give a brief description of the procedure so I can do more research on it.


- Also, how can IR spect. help to differentiate b/w two optical isomers in an amino acid metal complex?


thanks for taking the time to read this!

[shelanachium]

If the complex is charged it is crystallised with an optically active counterion, usually obtained from a substance of natural origin (therefore optically pure). Traditionally, cationic species crystallised with camphorsulfonic acid, anionic species with the alkaloid brucine, though many other chiral acids or bases can be used.

If, for example, we have D and L [Co(en)3]3+ , if crystallised with D-camphorsulfonic acid the two salts {D-[Co(en)3]3+ [D-camphorsulonate-]3} and {L-Co(en)3]3+ [D-camphorsulfonate-]3}are obtained, which are likely to differ in solubility, being different compounds and not mirror-images of each other. These can then be separated from each other.

Chromatographic methods will work for charged or neutral compounds, but only if the chromatography column is filled with a chiral substance, e.g. a polymer with optically active groups attached.

IR spectroscopy will not distinguish optical isomers, vibrational modes in both forms will be the same.

[celtic07]

IR spectroscopy will not distinguish optical isomers, vibrational modes in both forms will be the same.

Does that fact that it is an AMINO ACID metal complex make any difference at all? I know it shouldnt for optical isomers in general, however there are a few compounds such as amphetamines etc...for which it works.