Sodium dl-phenylglycinate trihydrate: Structural, vibrational and theoretical studies

Abstract

The PGLYNa·3H 2O crystal belongs to the P2 1/ n space group of monoclinic system, Z = 4. The asymmetric part of the unit cell consists of one phenylglycine anion, one sodium cation and three water molecules. Each Na + ion is surrounded by six O atoms coming from five different water molecules and one carboxyl group of PGLY with the mean Na +⋯O distance of 2.41 Å. The crystal is built up from layers extending parallel to the (0 1 0) plane. The layers are formed by water molecules, sodium cations and phenylglycinate anions held together by weak O–H⋯O and medium strength N–H⋯O hydrogen bonds. The phenyl rings are located outside the layer and are arranged in an off-centered parallel orientation. The π-stacking interaction has been detected with the centroid–centroid separation between the neighboring aromatic rings equal to 6.199 Å. The infrared and Raman spectra of the crystalline sample are presented and discussed in relation to the theoretical predictions performed for the model compound PGLYNa·5H 2O at the B3LYP/6-311++G(2d,2p) level. The detailed assignment of the IR and R spectra has been made on the basis of both earlier reports on the similar compounds and the theoretically predicted vibrational data.