Commercial escitalopram oxalate crystallizes as a hydrated adduct with oxalic acid, in the space group P21 with a = 8.029897(21), b = 25.09397(6), c = 11.138930(31) Å, β = 106.7759(2)°, V = 2148.992(7) Å3, and Z = 4. The agreement of the Rietveld and previous single-crystal structures is excellent; the root-mean-square Cartesian displacements of the non-H atoms of the two independent cations are 0.076 and 0.067 Å, respectively. The water molecule refined to a slightly different position and occupancy. The pattern is included in the Powder Diffraction File™ (PDF®) as entry 00-064-1507.
