Conformational difference between mono- and diprotonated cis-2,5-diphenylpiperazinium salts in the solid state

Conformation of 1,4-dineopentyl-2,5-cis-diphenylpiperazine and its diammonium salts: remarkable change in conformation depending upon the counter anion

The free base of 1,4-dineopentyl-2,5-diphenylpiperazine takes a chair conformation in CDCl3, while the conformation of its diammonium salts changes depending upon the counter anion.