The hydrogen-bonding patterns of 3-phenylpropylammonium benzoate and 3-phenylpropylammonium 3-iodobenzoate: generation of chiral crystals from achiral molecules.
The crystal structures and hydrogen-bonding patterns of 3-phenylpropylammonium benzoate, C(9)H(14)N(+) x C(7)H(5)O(2)(-), (I), and 3-phenylpropylammonium 3-iodobenzoate, C(9)H(14)N(+) x C(7)H(4)IO(2)(-), (II), are reported and compared. The addition of the I atom on the anion in (II) produces a different hydrogen-bonding pattern to that of (I). In addition, the supramolecular heterosynthon of (II) produces a chiral crystal packing not observed in (I). Compound (I) packs in a centrosymmetric fashion and forms achiral one-dimensional hydrogen-bonded columns through charge-assisted N-H...O hydrogen bonds. Compound (II) packs in a chiral space group and forms helical one-dimensional hydrogen-bonded columns with 2(1) symmetry, consisting of repeating R(4)(3)(10) hydrogen-bonded rings that are commonly observed in ammonium carboxylate salts containing chiral molecules. This hydrogen-bond pattern, which has been observed repeatedly in ammonium carboxylate salts, thus provides a means of producing chiral crystal structures from achiral molecules.
Lemmerer
Andreas
A
Centre for Supramolecular Chemistry Research, Department of Chemistry, University of Cape Town, Rondebosch, South Africa. andreas.lemmerer@uct.ac.za