Neutral and cationic half-sandwich arene ruthenium, Cp*Rh and Cp*Ir oximato and oxime complexes: Synthesis, structural, DFT and biological studies

摘要

The reaction of [(p-cymene)RuCl2](2) and [Cp*MCl2](2) (M = Rh/Ir) with chelating ligand 2-pyridyl cyanoxime {pyC(CN) NOH} leads to the formation of neutral oximato complexes having the general formula [(arene) M{pyC(CN) NO} Cl] {arene = p-cymene, M = Ru, (1); Cp*, M = Rh (2); Cp*, M = Ir (3)}. Whereas the reaction of 2-pyridyl phenyloxime {pyC(Ph)NOH} and 2-thiazolyl methyloxime {tzC(Me) NOH} with precursor compounds afforded the cationic oxime complexes bearing formula [(arene) M{pyC(ph)NOH} Cl](+) and [(arene) M{tzC(Me) NOH} Cl](+) {arene = p-cymene M = Ru, (4), (7); Cp*, M = Rh (5), (8); Cp*, M = Ir (6), (9)}. The cationic complexes were isolated as their hexafluorophosphate salts. All these complexes were fully characterized by analytical, spectroscopic and X-ray diffraction studies. The molecular structures of the complexes revealed typical piano stool geometry around the metal center within which the ligand acts as a NN' donor chelating ligand. The Chemo-sensitivity activities of the complexes evaluated against HT-29 (human colorectal cancer), and MIAPaCa-2 (human pancreatic cancer) cell line showed that the iridium-based complexes are much more potent than the ruthenium and rhodium analogues. Theoretical studies were carried out to have a deeper understanding about the charge distribution pattern and the various electronic transitions occurring in the complexes. (C) 2016 Elsevier B.V. All rights reserved.