Complexes of palladium(II) chloride with histidine methylester, X-ray crystal structure of pd(HisOMe)Cl 2. Ternary complexes of palladium(II) with histidine methylester and nucleosides

Abstract

The interaction of palladium(II) chloride, PdCl 2, with L-histidine methylester (HisOMe) dihydrochloride has been studied in aqueous solution and the complex Pd(HisOMe)Cl 2 was isolated and characterized by elemental analysis, and IR and 1H 1NMR spectroscopy and its structure has been determined by X-ray diffraction. The orthorhombic symmetry of the compound indicated that it belongs to the space group P2 12 12 1. The determined interatomic distances are, PdCl(1): 2.306(1), PdCl(2): 2.305(1), PdN[N(1) of the imidazole ring]: 2.019(3), and PdN (NH 2 the exocyclice amino group): 2.043(3) Å. The complex Pd(HisOMe)Cl 2 further reacts with nucleosides (Nucl) in methanolic solutions to give the tertiary complexes [Pd(HisOMe)(Nucl)Cl]Cl and [Pd(HisOMe(Nucl) 2]Cl 2, depending on the Rd(HisOMe)Cl 2 to Nucl molar ratio, which were characterized with elemental analysis, conductivity measurements, and various spectroscopic methods. The complexes with N(1)H (imino ionizable proton, Hnucl = guanosine, inosine) undergo proton dissociation and ester hydrolysis, and in the case of the bis-nucleoside complexes loss of one coordinated nucleoside molecule, in neutral solutions and complexes of the formulas Pd(His)(guo) and Pd(His)(ino) were isolated.