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In case of organic ligands there are several techniques for purification, but in case of metal complex (using $\ce{Cr,Mn,Fe,Co}$ as central metals), I have not seen any literature for the purification of them except recrystallization.

Can we do column chromatography for the purification of metal complexes?

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  • $\begingroup$ Depends on the specific complex. Some are ameanable to columning, others decompose. I think generally if things are crystalline and will recrystallise its a whole lot easier to purify that way. Ferrocene and acetyl ferrocene are two classic examples of iron complexes that can be columned $\endgroup$ – NotEvans. Jul 27 '16 at 14:20
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For some yes, for some no. Typically, the ‘more organic’ a complex gets, the easier it would be to purify it by column chromatography.

Example: I synthesised zincporphyrin complexes in my master’s thesis and used silica gel columns. When synthesising the porphyrin itself, if I used sodium carbonate to neutralise propionic acid used in the reaction, I would get a (green, assumed) sodium complex which I could separate from the free porphyrin again by column chromatography.

Remember though, that many complexes are very polar and thus difficult to separate on standard phase columns.

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Of course you can, but it really depends on your complex stability, the stationary phase and the solvent.

The first test you should carry out is a "2D TLC": cut a TLC plate to be a square. Draw a line at 1cm of the border in two adjacent borders (so the 2 lines intersect at one point). Put your sample at that exact intersection point then elute the TLC along one axis all the way up. Dry it quickly but without too much heating. Then elute it along the other axis. Dry it and reveal it: stable compounds have the exactly same Rf in the 2 dimensions (because they do not change), so their final spot is on the diagonal; unstable compounds will decompose to create new molecules which are more polar or less polar than their precursor. This will lead to spots out of the diagonal.

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  • $\begingroup$ thanku sir for ur advice, for more knowledge about this technique, can u send me any reference literature or video.. $\endgroup$ – ANKIT Jul 28 '16 at 7:03
  • $\begingroup$ Have a look at chem.chem.rochester.edu/~nvd/pages/… $\endgroup$ – SteffX Jul 28 '16 at 10:46

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