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Issue 2, 2014
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Formation and reactivity of an (alkene)peroxoiridium(III) intermediate supported by an amidinato ligand

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Abstract

An IrI complex of an acetamidinato ligand was synthesized by reaction of N,N′-diphenylacetamidine, PhN[double bond, length as m-dash]C(Me)NHPh, with either MeLi and [{Ir(cod)}2(μ-Cl)2] or [{Ir(cod)}2(μ-OMe)2] and was characterized by X-ray crystallography as a mononuclear complex, [Ir{PhNC(Me)NPh}(cod)] (1; where cod = 1,5-cyclooctadiene). Reaction of 1 with CO afforded a dinuclear carbonyl complex, [{Ir(CO)2}2{μ-PhNC(Me)NPh-κNN′}2] (2), as indicated by EI mass spectrometry and solution- and solid-state IR spectroscopy [νCO (n-pentane) = 2067, 2034 and 1992 cm−1]. Activation of O2 by 1 in solution at 20 °C was irreversible and produced an (alkene)peroxoiridium(III) intermediate, [Ir{PhNC(Me)NPh}(cod)(O2)] (3), which was characterized by one- and two-dimensional NMR techniques and IR spectroscopy (for 3, νOO = 860 cm−1; for 318O2, νOO = 807 cm−1). Complex 3 oxidized PPh3 to OPPh3, and its decay in the absence of added substrates followed by reaction with cod yielded 4-cycloocten-1-one and a minor amount of 1. In comparison with the results for the previously reported guanidinato complex [Ir{PhNC(NMe2)NPh}(cod)(O2)] (4), the formation of 3 and its reaction with PPh3 are significantly faster, indicating considerable ligand effects in these reactions.

Graphical abstract: Formation and reactivity of an (alkene)peroxoiridium(iii) intermediate supported by an amidinato ligand

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Publication details

The article was received on 20 Aug 2013, accepted on 29 Sep 2013 and first published on 14 Oct 2013


Article type: Paper
DOI: 10.1039/C3DT52283K
Citation: Dalton Trans., 2014,43, 527-537
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    Formation and reactivity of an (alkene)peroxoiridium(III) intermediate supported by an amidinato ligand

    M. R. Kelley and J. Rohde, Dalton Trans., 2014, 43, 527
    DOI: 10.1039/C3DT52283K

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