Bis(2-methyl-imidazolium) fumarate dihydrate

In the title compound, 2C(4)H(7)N(2) (+)·C(4)H(2)O(4) (2-)·2H(2)O, the asymmetric unit consists of one 2-methyl-imidazolium cation, half a fumarate dianion and one water mol-ecule. There is an inversion center at the mid-point of the central C-C bond of the fumarate anion. In the crystal structure, mol-ecules are linked into a three-dimensional network by inter-molecular N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds. In addition, there are weak π-π stacking inter-actions with centroid-centroid distances of 3.640 (1) Å.