Crystal structure of a second monoclinic polymorph of 3-methoxybenzoic acid with Z′ = 1

A new polymorphic form of the title compound, C8H8O3, is described in the centrosymmetric monoclinic space group P2(1)/c with Z' = 1 as compared to the first polymorph, which crystallizes with two conformers (Z' = 2) in the asymmetric unit in the same space group. In the crystal of the second polymorph, inversion dimers linked by O-H center dot center dot center dot O hydrogen bonds occur and these are linked into zigzag chains, propagating along the b-axis direction by C-H center dot center dot center dot O links. The crystal structure also features a weak pi-pi interaction, with a centroid-to-centroid distance of 3.8018 (6) angstrom. The second polymorph of the title compound is less stable than the reported first polymorph, as indicated by its smaller calculated lattice energy.