Details

Autor(en) / Beteiligte

• Andris, Erik
• Navrátil, Rafael
• Jašík, Juraj
• Puri, Mayank
• Costas, Miquel
• Que, Lawrence
• Roithová, Jana

Titel

Trapping Iron(III)–Oxo Species at the Boundary of the “Oxo Wall”: Insights into the Nature of the Fe(III)–O Bond

Ist Teil von

• Journal of the American Chemical Society, 2018-10, Vol.140 (43), p.14391-14400

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2018

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Terminal non-heme iron­(IV)–oxo compounds are among the most powerful and best studied oxidants of strong C–H bonds. In contrast to the increasing number of such complexes (>80 thus far), corresponding one-electron-reduced derivatives are much rarer and presumably less stable, and only two iron­(III)–oxo complexes have been characterized to date, both of which are stabilized by hydrogen-bonding interactions. Herein we have employed gas-phase techniques to generate and identify a series of terminal iron­(III)–oxo complexes, all without built-in hydrogen bonding. Some of these complexes exhibit ∼70 cm–1 decrease in ν­(Fe–O) frequencies expected for a half-order decrease in bond order upon one-electron reduction to an S = 5/2 center, while others have ν­(Fe–O) frequencies essentially unchanged from those of their parent iron­(IV)–oxo complexes. The latter result suggests that the added electron does not occupy a d orbital with FeO antibonding character, requiring an S = 3/2 spin assignment for the nascent FeIII–O– species. In the latter cases, water is found to hydrogen bond to the FeIII–O– unit, resulting in a change from quartet to sextet spin state. Reactivity studies also demonstrate the extraordinary basicity of these iron­(III)–oxo complexes. Our observations show that metal–oxo species at the boundary of the “Oxo Wall” are accessible, and the data provide a lead to detect iron­(III)–oxo intermediates in biological and biomimetic reactions.