Hydrogen bonding and C-H - X interactions in two triclinic phases of 4-carboxyquinolinium chloride monohydrate

The title substance, C10H8NO2+. Cl-. H2O, crystallized in the centrosymmetr ic space group P (1) over bar in two phases, alpha and beta, each with one organic cation, one Cl- ion and one water molecule in the asymmetric unit. The principal structural difference in the two asymmetric units lies in the relative orientation of the water molecule. Three hydrogen bonds in the al pha phase have donor-acceptor distances (N ... Cl or O ... Cl) ranging from 3.052 (1) to 3.189 (2) Angstrom, while one has an O ... O distance of 2.60 3 (3) Angstrom. Three hydrogen bonds in the beta phase have donor-acceptor distances (N ... Cl or O ... Cl) ranging from 3.044 (2) to 3.206(2) Angstro m, while two have O ... O distances of 2.586 (2) and 3.147 (3) Angstrom. Th e H atoms in all these hydrogen bonds are ordered. Each of these phases has five leading C-H ... X interactions, for which the H ... X distances are l ess than, or at most slightly greater than, the corresponding van der Waals radius sums. Taken together, these hydrogen bonds and C-H ... X interactio ns form a three-dimensional network of interactions in each phase. The dihe dral angle between the best-fit quinoline core plane and the carboxyl group plane is 25.9 (1)degrees for the alpha phase and 20.0(1)degrees for the be ta phase.