When i prepare the complexes it forms in amorphous state i want to make crystals of complex.my complexes soluble DMSO but when i dissolved in it and pour insoluble solvent it was oxidized.
Hi
Crystallisation of metal complexes (or any organic/inorganic molecule) can sometimes be tricky. There are multiple approaches you can try, but I am afraid this completely depends on your particular system and you can't do much else other than keep trying. However, it seems that you have first a problem with decomposition that you should solve before trying to crystallise the complex.
If you observe that your complex is being oxidised when trying to crystallise it, you need to avoid that from happening first. First of all, try looking into the literature for crystallisation/isolation methods for similar complexes. You will probably need to work under inert atmosphere and use dry solvents.
DMSO is in general a poor solvent choice for very reactive metal complexes for various reasons: very high boiling point which makes it difficult to remove completely, it has high affinity for coordinating to metals, it is quite difficult to dry it properly, so you will end up having some water in there that can decompose your sensitive products, and also the sulfoxide group can act as an oxidant. However, if it you have no other choice, try working under nitrogen and using dry solvents and probably this will stop the oxidation of your complexes. If it still was oxidised, consider using other solvents: hexane, toluene, DCM, Et2O, etc.
Once the decomposition problem is solved, you can then try crystallising the product. There are several techniques you can use: dissolving your product and lowering the temperature to induce crystallisation, diffusion, or using an antisolvent, among others. There is a lot of information online and books on crystallisation and the theory behind it if you are interested in the topic, although in my experience crystallisation of your products in the lab is usually not an exact science. You typically have to try multiple things.
Hope this helps. Good luck!
Best wishes,
Martí
Usually The organic compounds they will dissolved in volatile solvents like ethyl acetate completely, and they will keep in room temperature for slowly evaporation, mean time the slowly evaporation crystals will form. Please check your complex other than DMSO. Then you try the same. DMSO is not suitable for crystallization.
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