Weakly coordinating anion

Weakly coordinating anions, sometimes (inaccurately) called non-coordinating anions, are anions (chemicals that have a negative electric charge) that do not take part in many chemical reactions. In particular, they do not easily make coordination complexes or lose atoms to abstraction.

Weakly coordinating anions are important for dealing with very reactive cations (positively charged chemicals). In solids and liquids, ions need to be paired up to get a neutral electric charge, but unstable cations will react with paired anions to make different compounds, rather than make an ionic bond and a salt. Using a weakly coordinating anion helps stop these reactions so the original cation can be studied.

The conjugate bases of many superacids are weakly coordinating anions, including perchlorate and the Lewis adducts found in mixed superacids like fluoroantimonic acid. An important group of weakly coordinating anions are the fluorinated tetraphenylborate anions, which are some of the least reactive anions known.

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Category:Anions