In: Chemistry
Why is NH4BF4 and not NaBF4 a preferred reagent for anion exchange with a transitionmetal chloride? Please Explain.
We perform reactions under aprotic polar solvents like THF, acetone, dioxane,CHCl3, CH2Cl2 etc. If your complex is soluble in relatively nonpolar solvents such as acetone or dichloromethane, you can often use sodium tetrafluoborate for a metathesis reaction, as sodium chloride (from NaBF4 + Transition metal chloride) isn't very soluble in such solvents.
Anion exchange resins are used for replacing anions of some transition metal salts or complexes. However, in case of such sensitive complexes, decomposition is expected by the required strong acids. In some cases portion of the transition metal (complex) can stick on the resin.
NH4BF4 is known to be a PTC (Phase Transfer Catalyst), in general quaternary ammonium salts are used as PTC reagents as NaBF4 will not. PTC will shuttle between aqueous and organic phases thereby increase and enhances the reactions.
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