Supramolecular structures of three configurational isomers of 2-phenylethanaminium malate(1-)

In rac-1-phenylethanaminium rac-malate(1-), C8H12N+.-C4H5O5-, ( I), the anions are linked by two inter- anion O-H...O hydrogen bonds into sheets generated by a glide plane and hence containing both enantiomers of the anion. The cations are linked to the anion sheets by three N-H...O hydrogen bonds, such that cations of R configuration are bonded to one face of the sheet and cations of S configuration are bonded to the other face. In (R)-1-phenylethanaminium (S)-malate(1-), C8H12N+.C4H5O5-, (III), the anions are again linked by two O-H...O hydrogen bonds, in one of which the H atom is disordered over two sites, into sheets very similar to those in ( I) but which are generated in ( III) by translation and so contain only a single enantiomer. The cations in ( III) are linked to the anion sheets by three N-H...O hydrogen bonds, but the cations are bonded to only one face of the anion sheet. Co-crystallization of (R)-1-phenylethanamine with rac-malic acid gives the salt (R)-1-phenylethanaminium malate(1(-)) C8H12N+.C4H5O5-, (II), with a structure very similar to that of ( III) but where only ca 75% of the anion sites are occupied by (S)-malate(1-), with the remaining 25% occupied by (R)-malate(1-). The layers in (II) show a significant displacement along the [001] direction compared with those in ( III).