Bis(2,3-diamino­pyridinium) bis­(μ-pyridine-2,6-dicarboxyl­ato)-κ(4) O (2),N,O (6):O (6);κ(4) O (2):O (2),N,O (6)-bis­[aqua­(pyridine-2,6-dicarboxyl­ato-κ(3) O (2),N,O (6))bis­muthate(III)] tetra­hydrate

In the centrosymmetric dinuclear complex anion of the title compound, (C(5)H(8)N(3))(2)[Bi(2)(C(7)H(3)NO(4))(4)(H(2)O)(2)]·4H(2)O, the Bi(III) atom is eight-coordinated in an N(2)O(6) environment and has a distorted bicapped trigonal–prismatic coordination environment. Extensive inter­molecular O—H⋯O, N—H⋯O and weak C—H⋯O hydrogen bonds lead to the stability of the crystal structure. Inter­actions between one C—H group of the 2,3-diamino­pyridinium [(2,3-dapyH)(+)] cation and the aromatic ring of the pyridine-2,6-dicarboxyl­ate (pydc) ligand (C—H⋯centroid distance = 2.78 Å) and π–π inter­actions between the (2,3-dapyH)(+) cations and between the (2,3-dapyH)(+) cation and the pydc ligand [centroid–centroid distances = 3.489 (5) and 3.694 (5) Å] are observed.