Separation of KCl from potassium chromium(III) PDTA

[Mayhem]

The mentioned coordination complex has been prepared where KCl is a significant byproduct. The salt and the complex appear to be readily soluble in the same solvents. Despite the organic ligand (PDTA), it is not soluble in polar organic solvents, at least to a degree where it can be used for separation. Protation is most likely not possible without degrading the complex.

I can't find any literature that puports a simple separation method. I thought that perhaps the complex could have its cation displaced by an organic cation (an methyltetraammonium chloride, for example), which is also water soluble. Not sure if this would work.

Literature shows that the silver salt of potassium chromium PDTA is also insoluble[1], so a simple AgNO3 displacement also wouldn't work.

Any ideas?

 

[DrDu]

There are syntheses which don't seem to have KCl as a byproduct, e.g. https://www.mdpi.com/2313-0105/9/12/573 or here https://www.cell.com/joule/pdf/S2542-4351(19)30318-6.pdf
Even if both substances are in principle soluble in the same solvents, when you try to crystallize them, usually one of them will crystallize first.