Perindoprilat monohydrate

The title compound [systematic name: (1S)-2-((S)-{1-[(2S,3aS,7aS)-2-carboxyoctahydro-1H-indol-1-yl]-1-oxopropan-2-yl}azaniumyl)pentanoate monohydrate], C17H28N2O5 center dot H2O, (I)center dot H2O, the active metabolite of the antihypertensive and cardiovascular drug perindopril, was obtained during polymorphism screening of perindoprilat. It crystallizes in the chiral orthorhombic space group P2(1)2(1)2(1), the same as the previously reported ethanol disolvate [Pascard, Guilhem, Vincent, Remond, Portevin & Laubie (1991). J. Med. Chem. 34, 663-669] and dimethyl sulfoxide hemisolvate [Bojarska, Maniukiewicz, Sieron, Fruzinski, Kopczacki, Walczynski & Remko (2012). Acta Cryst. C68, o341-o343]. The asymmetric unit of (I)center dot H2O contains one independent perindoprilat zwitterion and one water molecule. These interact via strong hydrogen bonds to give a cyclic R-2(2)(7) synthon, which provides a rigid molecular conformation. The geometric parameters of all three forms are similar. The conformations of the perhydroindole group are almost identical, but the n-alkyl chain has conformational freedom. A three-dimensional hydrogen-bonding network of O-H center dot center dot center dot O and N-H center dot center dot center dot O interactions is observed in the crystal structure of (I)center dot H2O, similar to the other two solvates, but because of the presence of different solvents the three crystal structures have diverse packing motifs. All three solvatomorphs are additionally stabilized by nonclassical weak C-H center dot center dot center dot O contacts.