Reinvestigation of 4-methyl-anilinium dihydrogen phosphite.

The crystal structure of the title compound, C(7)H(10)N(+)·H(2)PO(3) (-), has been reported previously by Sabounchei & Naghipour [Asian J. Chem. (2003) ▶, 15, 1677-1686]. A new look at this compound has revealed doubling of the unit cell. The asymmetric unit consists of two 4-methyl-anilinium cations and two dihydrogen phosphite anions. The crystal structure is built upon alternating layers of organic cations and dihydrogen phosphite anions stacked along c. The organic layer is stabilized by C-H⋯π interactions. Weak aromatic π-π stacking interactions with centroid-centroid distances of 4.6147 (12), 4.6917 (12), 4.6932 (13) and 4.8366 (13) Å are also observed in the structure. The dihydrogen phosphite anions are linked by O-H⋯O hydrogen bonds into chains running parallel to the a-axis direction. These chains are connected to the cation layer by N-H⋯O hydrogen bonds.