Interactions in Crystals. 136. Protonated Dipyridylamine Salts with Different Anions: Monomeric Tetraphenylborate as well as Bis(trifluormethylsulfonate), Dimeric Squarate and Polymeric Chloride Dihydrate
Di(pyrid‐2‐yl)amine is monoprotonated by acetic, squaric as well as hydrochloric acid and diprotonated by trifluoromethylsulfonic acid. To explore the anion and hydrogen‐bridge dependency of its salts, crystals of the monomeric tetraphenylborate, the dimeric squarate as well as the bis(trifluoromethylsulfonate) and the polymeric chloride hydrate have been grown and their structures determined: Separated by bulky tetraphenylborate anions, pyrid‐2‐yl(2′‐pyridinium) amine cation contains an intramolecular hydrogen bridge N⊕H…︁N and is slightly folded. The squarate salt dimer exhibits additional bridges, NH…︁O⊖ and OH…︁O. The severely twisted di(2‐pyridinium)amine dication is connected to its trifluormethylsulfonate counter anions by altogether three H‐bridges, two N⊕H…︁O and one NH…︁O. The chloride dihydrate crystallizes in layers of 16‐membered rings, formed from three Cl anions and five water molecules. The diversity of the hydrogen‐bridge dominated salt structures is discussed based on comparison with selected literature examples and on PM3 calculations.
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