The amino acids complexes of osmium(II), i. e.[Os(eta 6-p-cymene)(eta 1-N-(rac)-phenylglycinemethyl ester) Cl-2](A) and [Os(eta 6-p-cymene) (eta 1-N,N'-(S)-phenylalanineamido) Cl] (B), were prepared by an ultrasound energy-assisted method at room temperature. The solid structures of the newly synthesized complexes were determined by single crystal X-ray analysis. In A, osmium is bonded to 2 chloride ligands, the eta 6-coordinated p-cymene molecule, and to a nitrogen atom of the corresponding amino acid derived ligand, whereas in the case of B the central osmium is surrounded by an N,N' bidentate amino amide ligand, by an eta 6-coordinated p-cymene molecule, and a chloride ligand. Both complexes have a pseudotetrahedral geometry. As shown by X-ray structure, A exhibited racemization of the corresponding ligand. The ligand retained its configuration in B with co-crystallization of the 2 diastereomers, ROsSC and SOsSC, in a single crystal.