Hi 

A route that has been used by nobel laureate J. F. Stoddart is to dissolve your complex in minimum H20 and then add a saturated solution of NH4PF6 which precipitates the desired product (in their case Blue Box). It works with a lot of similar systems as long as the cationic part is not very soluble in water.

Is the complex you're starting with neutral or are you trying to exchange the anion? In general, if you're trying to switch s a halide/strongly coordinating anion to something like PF6, a good method is to mix an excess of the silver salt of your desired anion with your starting metal complex in a small amount of relatively non-polar organic such as methylene chloride and then filter off the resulting precipitate. I do a TON of salt metathesis reactions and generally this works very well. Depending on the solubility of your starting material, you may need to use a more polar solvent, though I wouldn't go more polar than acetone or acetonitrile, as the Ag salt you're precipitating may be too soluble in more polar solvents. Addition of a ligand to replace the abstracted anion can also help drive the reaction forward.

Hi,

The other answers are OK

Are you sure about the charge of the complex before the addition of PF6-?

Which is the anion before PF6?

An excess of 10 in PF6 is necessary.

Try to evaporate 50% of the solvent, and wait  one night leaving the solution  at room temperature.

The complex we expect is of +ve charge. I have kept one night leaving the solution at room temperature. still the solution remained the same

Most of them have given the precise solution to your problem.

First you should tell whether it is a neutral complex or already a cationic complex.

If it is a neutral complex,  does the complex has a metal-halide bond (M-X) in it?

Then use KPF6 or if you can afford AgPF6, use it in a polar solvent and you should be able to form PF6 salt.

If it is already an ionic complex, what is the counter anion, if it is a halide, no problem, still you can easily replace it with KPF6 .

Thank you all

Hi,

If you are still looking for a reference, I hope the following ref might help you..

Article Formation of a Metal-to-Nitrogen Bond of Normal Length by a ...

To follow up my previous answer, as I'm sure many of you know, silver works very well but can also do nefarious things, so it's best to use alkali metal salts if possible (they're cheaper and usually cause less problems!)

Dear Derek Would you recommend silver for exchanging K+ for Li+ for getting LiPF6? Thanks in avance