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 PdL^EtCl₂ (L^Et is ethyl ester of LH) are synthesized. The X-ray diffraction analysis (СIF file ССDC no. 1471432) shows that the single crystals of the [PdL^EtCl₂] complex belong to the racemate. The crystal structure contains (+)- and (–)-enantiomeric molecules of the mononuclear complex. Ligand L^Et 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 [PdL^EtCl₂] 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 PdL^EtCl₂ 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 [PdL^EtCl₂].