Ligand-centred reactivity of bis(picolyl)amine iridium: sequential deprotonation, oxidation and oxygenation of a "non-innocent" ligand

Tejel, C., del Rio, M.P., Ciriano, M.A., Reijerse, E.J., Hartl, F. ORCID: https://orcid.org/0000-0002-7013-5360, Zalis, S., Hetterscheid, D.G.H., Spithas, N.T.I. and de Bruin, B. (2009) Ligand-centred reactivity of bis(picolyl)amine iridium: sequential deprotonation, oxidation and oxygenation of a "non-innocent" ligand. Chemistry- A European Journal, 15 (44). pp. 11878-11889. ISSN 0947-6539 doi: 10.1002/chem.200901017

Abstract/Summary

Treatment of [Ir(bpa)(cod)](+) complex [1](+) with a strong base (e.g., tBuO(-)) led to unexpected double deprotonation to form the anionic [Ir-(bpa-2H)(cod)](-) species [3](-), via the mono-deprotonated neutral amido complex [Ir(bpa-H)(cod)] as an isolable intermediate. A certain degree of aromaticity of the obtained metal-chelate ring may explain the favourable double deprotonation. The rhodium analogue [4](-) was prepared in situ. The new species [M(bpa-2H)(cod)](-) (M = Rh, Ir) are best described as two-electron reduced analogues of the cationic imine complexes [M-I(cod)(Py-CH2-N=CH-Py)](+). One-electron oxidation of [3](-) and [4](-) produced the ligand radical complexes [3]* and [4]*. Oxygenation of [3](-) with O-2 gave the neutral carboxamido complex [Ir(cod)(py-CH2-N-CO-py)] via the ligand radical complex [3]* as a detectable intermediate.