Crystal structure of (4-meth­oxy­phen­yl)[(4-meth­oxy­phen­yl)phospho­nato]dioxidophosphate(1−) 2-amino-6-benzyl-3-eth­oxy­carbon­yl-4,5,6,7-tetra­hydro­thieno[2,3-c]pyridin-6-ium

The asymmetric unit of the title mol­ecular salt, C(17)H(21)N(2)O(2)S(+)·C(14)H(15)O(7)P(2) (−), comprises two cations and two anions. Each cation features an intra­molecular N—H⋯O hydrogen bond, which closes an S(6) ring; in each case the hydro­pyridine ring adopts a half-chair conformation. In the anions, the dihedral angles between the aromatic rings are 64.1 (2) and 54.9 (2)°. In each case, the diphosphate groups are close to eclipsed [C—P⋯P—C pseudo-torsion angles = 11.6 (2) and −19.3 (2)°]. One of the meth­oxy groups in each anion is disordered over two orientations in a 0.539 (18):0.461 (18) ratio in one anion and 0.82 (2):0.18 (2) in the other. In the crystal, O—H⋯O and N—H⋯O hydrogen bonds link the components into [100] chains. Numerous C—H⋯O inter­actions cross-link the chains into a three-dimensional network.