Synthesis and structure of trans-2,5-dimethylpiperazine-1,4-diium dihydrogen diphosphate

Abstract

In the title salt, C 6 H 16 N 2 2+ ·H 2 P 2 O 7 2− , the complete dication is generated by a crystallographic centre of symmetry with the methyl groups in equatorial orientations. The complete dianion is generated by a crystallographic twofold axis with the central O atom lying on the axis: the P—O—P bond angle is 135.50 (12)°. In the crystal, the dihydrogen diphosphate anions are linked by O—H...O hydrogen bonds, generating (001) layers. The organic cations bond to the inorganic layers by way of N—H...O and C—H...O hydrogen bonds. A Hirshfeld surface analysis shows that the most important contributions for the crystal packing are from O...H/H...O (60.5%) and H...H (39.4%) contacts.