1192188-44-5Relevant academic research and scientific papers
A hydrogen-bond facilitated cycle for oxygen reduction by an acid- and base-compatible iron platform
Soo, Han Sen,Komor, Alexis C.,Lavarone, Anthony T.,Chang, Christopher J.
, p. 10024 - 10035 (2009)
We report a hydrogen-bond functionalized N4Py ligand platform (N,N-bis(2-R-6-pyridylmethyl)-N-bis(2-pyridyl)methylamine; R = neopentyl-NH, N4Py2NpNH, 9; R = phenyl-NH, N4Py2PhNH, 10) and the ability of its iron(II)triflate [N4Py2RFeII(OTf)][OTf] complexes (R = NpNH, 11; R = PhNH, 12) to activate and reduce dioxygen in a synthetic cycle by coupled proton and electron transfer. A pair of iron(III)-hydroxlde [N4Py2RFeIII(OH)][OTf]2 complexes (R = NpNH, 13; R = PhNH, 14) are isolated and structurally and spectroscopically characterized after exposure of the iron(II)-triflate precursors to 1 atm of O2 at ambient temperature. The stability of this system to acids and bases allows regeneration of the labile iron(II)-triflate starting materials by sequential electron and proton transfer with cobaltocene and triflic acid, respectively, or through direct proton-coupled reduction with ascorbic acid. In the stepwise process, reduction of the iron(III)-hydroxide complexes with cobaltocene gives structurally homologous iron(II)-hydroxlde [N4Py2RFeII(OH)][OTf] congeners (R = NpNH, 15; R = PhNH, 16) that can be prepared independently from 11 and 12 with 20% aq. NaOH. Additions of triflic acid to complexes 15 and 16 furnish the starting compounds 11 and 12, respectively, to complete the synthetic cycle. The combined data establish a synthetic cycle for O2 reduction by an iron platform that manages proton and electron transfer through its first and second coordination spheres.
