The crystal structure of metolazone has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Metolazone crystallizes in space group P-1 (#2) with a = 8.1976(5), b = 14.4615(69), c = 16.0993(86) Å, α = 115.009(18), β = 90.096(7), γ = 106.264(4)°, V = 1644.52(9) Å3, and Z = 4. The broad (02-1) peak at 3.42° 2θ indicates stacking faults along this direction. The crystal structure consists of alternating polar and hydrocarbon layers parallel to the ac-plane. Only one of the sulfonamide groups acts as a hydrogen bond donor. Both ring nitrogen atoms act as hydrogen bond donors, but one forms an N–H···N hydrogen bond, while the other participates in an N–H···O bond. The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™, to replace entry 00-066-1624.
