Crystal structure of valganciclovir hydrochloride, C ₁₄ H ₂₃ N ₆ O ₅ Cl

Abstract The crystal structure of valganciclovir hydrochloride has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. Valganciclovir hydrochloride crystallizes in space group P2 1 2 1 2 1 (#19) with a = 7.07758(23), b = 11.34599(27), c = 49.3041(22) Å, V = 3,959.22(22) Å 3 , and Z = 8. Solution and refinement of the structure were made difficult by the limited data range, the relatively large size of the structure, the broad diffraction peaks, the relatively low crystallinity, and the significant preferred orientation. The two independent cations are protonated at the N atoms of the valine side chains. The crystal structure is dominated by alternating layers of ring systems and protonated side chains/anions along the c -axis. In addition to the ammonium–Cl hydrogen bonds, the ring systems and side chains are linked into a three-dimensional network by hydrogen bonds. The two independent cations have very different conformations. N–H···Cl, N–H···O, O–H···N, O–H···O, and O–H···Cl, as well as C–H···Cl, C–H···N, and C–H···O hydrogen bonds, are prominent in the structure. The powder pattern is included in the Powder Diffraction File ™ (PDF ® ) as entry 00-071-1641.