Complexes PdCl2 with optically active hybrid ligands built of α-pinene and β-alanine molecules

Abstract

Complexes Pd(LH)Cl2 (LH is the N-derivative of β-alanine based on (–)-α-pinene) and PdLEtCl2 (LEt is ethyl ester of LH) are synthesized. The X-ray diffraction analysis (СIF file ССDC no. 1471432) shows that the single crystals of the [PdLEtCl2] complex belong to the racemate. The crystal structure contains (+)- and (–)-enantiomeric molecules of the mononuclear complex. Ligand LEt is bidentate chelating. The coordination PdCl2N2 core is a distorted square. The contacts Pd…Cl and hydrogen bonds N–H…Cl between molecules of the (+)- and (–)-enantiomers result in the formation of dimeric ensembles, which are joined into chains due to the C–H…Cl hydrogen bonds. According to the X-ray powder diffraction data, the products of the synthesis of complex [PdLEtCl2] contain both the racemate and (+)-enantiomer. The (+)-enantiomer is isolated by the recrystallization of the synthesis product. Complex Pd(LH)Cl2 is an optically active right-handed compound. According to the NMR data, complex PdLEtCl2 does not dissociate in a CDCl3 solution. The results of IR and NMR spectroscopy indicate that the molecular structure of complex Pd(LH)Cl2 is similar to that of [PdLEtCl2].