Abstract
In the title compound, 2C(8)H(12)NO(+)center dot H2P2O72-, the linked PO4 groups of the diphosphate anion are almost eclipsed and the P-O-P angle is 134.45 (7)degrees. In the crystal, infinite ribbons of H2P2O72- anions propagate in [100], being linked by strong O-H center dot center dot center dot O hydrogen bonds. The 4-methoxybenzylammonium cations bond to the diphosphate chains by N-H center dot center dot center dot O and C-H center dot center dot center dot O links, and are themselves linked by C-H center dot center dot center dot pi interactions.