Crystal structure of indacaterol hydrogen maleate (C24H29N2O3)(HC4H2O4)

The crystal structure of indacaterol hydrogen maleate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Indacaterol hydrogen maleate crystallizes in space group P-1 (#24) with a = 8.86616(9), b = 9.75866(21), c = 16.67848(36) Å, α = 102.6301(10), β = 94.1736(6), γ = 113.2644(2)°, V = 1273.095(7) Å3, and Z = 2 at 295 K. The crystal structure consists of layers of cations and anions parallel to the ab-plane. Traditional N–H⋯O and O–H⋯O hydrogen bonds link the cations and anions into chains along the a-axis. There is a strong intramolecular charge-assisted O–H⋯O hydrogen bond in the non-planar hydrogen maleate anion. There are also two C–H⋯O hydrogen bonds between the anion and cation. The cation makes a strong N–H⋯O hydrogen bond to the anion, but also acts as a hydrogen bond donor to an aromatic C in another cation. The amino group makes bifurcated N–H⋯O hydrogen bonds, one intramolecular and the other intermolecular. The hydroxyl group acts as a donor to another cation. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®).