Synthesis,molecular structure and solution chemistry of the iridium(III) complex imidazolium[trans(bisimidazole0tetrachloro iridate(III)](IRIM)

摘要

The iridiumQLl) complex imidazolium [trans(bisimidazole)tetrachloro iridate(IIL)3. (TRIM), isostructural to the well known rutheniun~1I1~ analogue, (ICR). has been prepared and characterised, both in the solid state and in solution, by X-ray diffraction and by a vaujety of physico-chemical techniques. Single crystal X-ray diffraction studies point out that this complex is isomorphous with ICR and with the rhodium(III) analogue. TRIM is moderately soluble in water and within a physiological phosphate buffer. Electronic spectra in the visible, show that the complex is stable for days at pH 7.4~ notably no significant chloride hydrolysis is observed over a period of 24 h at 25CC. Stability of TRIM within a physiological buffer was further tested and coixfirined by ‘ NMR spectra. The complex is stable toward treatment with either hydrogen peroxide or ascorbic acid or silver nitrate. The chemical behaviour in solution and the reactivity of TRIM are compared to those of ICR; implications· of the present results for possible pharmacological applications of TRIM and for a better understanding of the mechanism of action of ICR are discussed.