[itchyrain]

Hi all,

I'm having an issue with an anionic cyclometallated platinum complex (tetrabutylammonium counterion) I'm trying to purify. The literature prep states that for the final step you dissolve the product in the minimum amount of DCM, followed by slow addition of diethyl ether to ppt out the product, filter, wash and done. Whenever I complete the addition of the ether, I end up with a significant portion of the product stuck to the side of the glass flask. Sonication just results in the residue aggregating and remaining stuck to the side of the flask. I've tried a few other solvent systems, with no luck.

I was curious if anyone else has seen this kind of thing, and if there's any tips?

[fledarmus]

I haven't worked with inorganic materials, but that is a very common problem with organic materials because ether tends to absorb a lot of water. My solution has always been to make sure the ether is very dry before using it, and if that isn't good enough, to keep it under nitrogen so the humidity in the air doesn't cause a problem. Once I have a nice crystalline solid, in many cases, it doesn't pick up water from the air, but getting to the solid state can be a challenge.

It is also possible that you still have impurities that are interfering with crystallization. You may need to take your gummy precipitate, redissolve with dcm and ppt with ether a few times to get nice solid.

[Arkcon]

The problem may be as much to do with the vial itself as with the product or the solvent conditions.  You may try to use a different brand of glass vial, or switch to some teflon-lined plastic vial, or maybe try the reference you have to see if you can find the source of the vials.

[discodermolide]

As has been noted ether is terrible for this. You need to find another solvent system. Try azeotroping off any water etc with toluene and crystallise from toluene/DCM.