Half-sandwich type rhodium(III)-aminohydroxamate complexes: the role of the position of the amino group in metal ion binding

Parajdi-Losonczi, Péter László and Buglyó, Péter and Skakalova, Hana and Kasparkova, Jana and Lihi, Norbert and Farkas, Etelka (2018) Half-sandwich type rhodium(III)-aminohydroxamate complexes: the role of the position of the amino group in metal ion binding. NEW JOURNAL OF CHEMISTRY, 42 (10). pp. 7659-7670. ISSN 1144-0546

Text Rh-alaha_MS_final.pdf Restricted to Repository staff only Download (435kB) | Request a copy

Abstract

Complex formation equil. between [(η5-Cp*)RhIII(H2O)3]2+ and aminohydroxamic acids (2-amino-N-hydroxyacetamide (α-alahaH), 3-amino-N-hydroxypropanamide (β-alahaH) and 4-amino-N-hydroxybutanamide (GABAha, γ-abhaH)) having the primary amino group in different chelatable position to the hydroxamic function were studied by pH-potentiometric, 1H NMR and ESI-MS methods and formation consts. of the complexes present in aq. soln. are reported. Relative order of the pH-dependent conditional stability of the hydroxamate type (O,O) and (Namino,Nhydroxamato) chelates was found to det. in high extent the coordination modes both in the mono- and various dinuclear species formed. While with α-alaha-, the 5-membered (N,N) chelated mononuclear complex predominates, with β-alaha-, in a wide pH-range, very stable dinuclear cluster ions exist. With γ-abha-, in the most stable complexes, two ligands (in reverse variation) link two half-sandwich cations, coordinating each ligand via the hydroxamate chelate to one metal center, while via the amino-N to the other one. This arrangement seems to be further stabilized by a hydrogen bond as DFT calcns. support the extra stabilization effect of an internal H-bonding in [{(η5-Cp*)RhIII}2H-1(γ-abha)2]+. Synthesis, spectral (NMR, IR) and MS characterization of a novel complex with the iridium analog, [(η5-Cp*)IrIII(α-alaha)Br] (1) is also described. This complex was tested for its in vitro cytotoxicity using human-derived cancer cell lines (A2780, HeLa, DU-145, A549, and MCF-7) and showed insignificant anti-proliferative activity in the micromolar concn. range. [on SciFinder(R)]

Actions (login required)

Edit Item