The 1,4-diazabutadiene/1,2-enediamido non-innocent ligand system in the formation of iridaheteroaromatic compounds: Spectroelectrochemistry and electronic structure

0342383 - ÚFCH JH 2011 RIV CH eng J - Journal Article
Kaim, A. - Sieger, M. - Greulich, S. - Sarkar, B. - Fiedler, Jan - Záliš, Stanislav
The 1,4-diazabutadiene/1,2-enediamido non-innocent ligand system in the formation of iridaheteroaromatic compounds: Spectroelectrochemistry and electronic structure.
Journal of Organometallic Chemistry. Roč. 695, č. 7 (2010), s. 1052-1058. ISSN 0022-328X. E-ISSN 1872-8561
R&D Projects: GA AV ČR KAN100400702; GA MŠMT OC 139; GA MŠMT OC09043
Institutional research plan: CEZ:AV0Z40400503
Keywords : 1,4-diazabutadiene * electronic structure * iridium compounds
Subject RIV: CG - Electrochemistry
Impact factor: 2.205, year: 2010

Oxidation of the unambiguously characterized iridium(III)-enediamido complex IrCp*(RNCHCHNR), R = 2,6-dimethylphenyl, with six cyclically arranged p electrons was investigated using EPR and UV-vis spectroelectrochemistry. In contrast to a corresponding iminocatecholato system reported recently by Rauchfuss et al. [27] the two one-electron oxidation steps are not completely reversible, depending on the solvent. We attribute the electrochemical behavior observed in weakly coordinating dichloromethane and propylene carbonate solvents to an enhanced propensity for ligand addition: while neutral IrCp*(RNCHCHNR) remains coordinatively unsaturated with the strongly sigma and pi donating enediamido(2-) ligand mitigating the electron deficit, the oxidation to the less donating radical anion ligand (RNCHCHNR)(center dot-) or even to neutral 1,4-diazabutadiene is considered to induce a strong tendency for quasi-hexacoordination in [IrCp*(L)(RNCHCHNR)], L = solvent, halide, substrate.
Permanent Link: http://hdl.handle.net/11104/0185131