Bis(μ-3-carb-oxy-2-oxidobenzoato)-κO,O:O;κO:O,O-bis-[aqua-(2,2'-bipyridine-κN,N')copper(II)].

In the centrosymmetric dinuclear complex, [Cu(2)(C(8)H(4)O(5))(2)(C(10)H(8)N(2))(2)(H(2)O)(2)], the Cu(II) ion is coordinated by two N atoms from a bipyridine ligand, three O atoms from two 3-carb-oxy-2-oxidobenzoate dianions and the O atom of the water mol-ecule in a distorted octa-hedral geometry. The Cu--O(H) coordination [2.931 (3) Å] is very weak.

Melaminium sulfate.

In the title compound, C(3)H(8)N(6) (2+)·SO(4) (2-), the melaminium cations and sulfate anions are inter-connected by N-H⋯N and N-H⋯O hydrogen bonds, forming a layer in the (101) plane. The layers are connected through multiple hydrogen bonds and π-π stacking inter-actions (centroid-centroid distance of about 3.4 Å).