Structural and spectroscopic characterization of an Fe(VI) bis(imido) complex

Jorge L Martinez; Sean A Lutz; Hao Yang; Jiaze Xie; Joshua Telser; Brian M Hoffman; Veronica Carta; Maren Pink; Yaroslav Losovyj; Jeremy M Smith

doi:10.1126/science.abd3054

Structural and spectroscopic characterization of an Fe(VI) bis(imido) complex

Science. 2020 Oct 16;370(6514):356-359. doi: 10.1126/science.abd3054.

Authors

Affiliations

¹ Department of Chemistry, Indiana University, Bloomington, IN 47405, USA.
² Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.
³ Department of Chemistry, University of Chicago, Chicago, IL 60637, USA.
⁴ Department of Biological, Physical and Health Sciences, Roosevelt University, Chicago, IL 60605, USA.
⁵ Department of Chemistry, Indiana University, Bloomington, IN 47405, USA. smith962@indiana.edu.

PMID: 33060362
DOI: 10.1126/science.abd3054

Abstract

High-valent iron species are key intermediates in oxidative biological processes, but hexavalent complexes apart from the ferrate ion are exceedingly rare. Here, we report the synthesis and structural and spectroscopic characterization of a stable Fe(VI) complex (3) prepared by facile one-electron oxidation of an Fe(V) bis(imido) (2). Single-crystal x-ray diffraction of 2 and 3 revealed four-coordinate Fe centers with an unusual "seesaw" geometry. ⁵⁷Fe Mössbauer, x-ray photoelectron, x-ray absorption, and electron-nuclear double resonance (ENDOR) spectroscopies, supported by electronic structure calculations, support a low-spin (S = 1/2) d³ Fe(V) configuration in 2 and a diamagnetic (S = 0) d² Fe(VI) configuration in 3 Their shared seesaw geometry is electronically dictated by a balance of Fe-imido σ- and π-bonding interactions.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.