Optical resolution of racemic stilbenediamine (Stien) was performed by recrystallization of its diastereomeric adducts with ortho-paLladated (6)-N-isopropyl-ct-methylbenzylamine.The less soluble (ScRN,SS) diastereomer was studied by X-ray diffraction analysis. It was established that the crystal of this diastereomer consists of dimers formed vha association of two molecules of the mononuclear cationic complex with an additional molecule of free diamine of the same absolute configuration. The association occurs through a system of hydrogen bonds and weak agostic interactions. Based on the X-ray diffraction data, the procedure was improved for the resolution of stilbenediamine due to the more profitable use of the or~ho-palladated reagent. The Stien/Pd ratio in the diastereomer isolated was increased up to 3 : 2. The conformational features of the complex are discussed on the basis of tH NMR spectroscopy data.Ke 7 words: 1,2-diamines, ortho-palladated complexes, optical resolution, hydrogen bonds, metallacycle conformation, X-ray diffraction analysis, nuclear Overhaaser effect.Studies carried out over the last 25 years have clearly demonstrated the considerable potential oforthopalladated complexes as reagents for optical resolution of a wide diversity of substrates possessing ligand properties, namely, of mono-, z di-, 3a and polyphosphines, 3b arsinophosphines, 4 diarsines, s aminophosphines, 6 aminoarsines, 7 diimines, s iminophosphines, 9 iminoarsines, 1~ mercaptophosphines, tt mercaptoarsines, t2 amine sulfoxides, t3 phosphine sulfoxides, t4 arsine sulfoxides, 15 and aminocarboxylic acids. 16 One of the rare failures in utilization of this procedure involves an unsuccessful attempt at resolving the simplest vicinal diamine with the symmetry C2,
