Комплексоутворення 4-амінобензгідроксамової кислоти з іонами Ru(III), Rh(III) та Pd(II)

• Datum: 2014
• Hauptverfasser: Zborovskii, Yu. L., Babichuk, I. V., Orysyk, V. V., Orysyk, S. I., Pekhnyo, V. I., Vovk, M. V.
• Format: Artikel
• Sprache: Ukrainian
• Veröffentlicht: National University of Pharmacy 2014
• Schlagworte: 4-амінобензгідроксамова кислота; реакції комплексоутворення; комплекси Ru(III); Rh(III) та Pd(II); O; O’-координація; УДК 547.298.71 541.49
• Online Zugang: https://ophcj.nuph.edu.ua/article/view/ophcj.14.812
• Назва журналу: Journal of Organic and Pharmaceutical Chemistry

A series of hydroxamate and hydroximate complexes of Ru(III), Rh(III) and Pd(II) with 4-amino-N-hydroxybenzamide (AHBA) has been synthesized, and their IR, UV-Vis and NMR 1H spectral characteristics have been studied.It has been found that AHBA interacts with metal ions mainly by the type of O,O’-coordination, wherein the structure of the complexes is largely dependent on the pH of medium. In acidic and weakly acidic media AHBA predominantly forms hydroxamate complexes with coordination of hydroxamic acid in neutral or mono deprotonated states. In NMR 1H spectra of hydroxamate complexes a singlet of NH protones is shifted upfield, which is associated with formation of cyclic metal chelates. In alkaline or near neutral media AHBA reacts as dianion to form anionic type hydroxamate complexes. In NMR 1H spectra of such complexes the singlets of NH and OH are absent. Depending on the nature of the metal, the central ion forms a square-planar [complexes of Pd(II)] or octahedral [complexes of Ru(III)] coordination unit, and it confirms the presence of d-d transition in electronic absorption spectra. The most characteristic of absorption bands in IR-spectra of the complexes are oxime group N–O of stretching vibrations that undergo low frequency offset by Dν = -(24–44) cm-1. The results obtained, as well as analysis of the published data show that increase of pH in the complexation reactions of hydroxamic acids leads to bidentate coordination of AHBA with formation of five-membered metallocycles.