Stabilization of Low-Valent Iron(I) in a High-Valent Vanadium(V) Oxide Cluster

Montaha H Anjass; Katharina Kastner; Florian Nägele; Mark Ringenberg; John F Boas; Jie Zhang; Alan M Bond; Timo Jacob; Carsten Streb

doi:10.1002/anie.201706828

Stabilization of Low-Valent Iron(I) in a High-Valent Vanadium(V) Oxide Cluster

Angew Chem Int Ed Engl. 2017 Nov 13;56(46):14749-14752. doi: 10.1002/anie.201706828. Epub 2017 Oct 9.

Authors

Montaha H Anjass^{1

2}, Katharina Kastner¹, Florian Nägele², Mark Ringenberg³, John F Boas⁴, Jie Zhang⁵, Alan M Bond⁵, Timo Jacob², Carsten Streb¹

Affiliations

¹ Institute of Inorganic Chemistry I, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
² Institute of Electrochemistry, Ulm University, Albert-Einstein-Allee 47, 89081, Ulm, Germany.
³ Institute of Inorganic Chemistry, Stuttgart University, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
⁴ School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia.
⁵ School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia.

PMID: 28906058
DOI: 10.1002/anie.201706828

Abstract

Low-valent iron centers are critical intermediates in chemical and bio-chemical processes. Herein, we show the first example of a low-valent Fe^I center stabilized in a high-valent polyoxometalate framework. Electrochemical studies show that the Fe^III -functionalized molecular vanadium(V) oxide (DMA)[Fe^III ClV^V₁₂ O₃₂ Cl]^3- (DMA=dimethylammonium) features two well-defined, reversible, iron-based electrochemical reductions which cleanly yield the Fe^I species (DMA)[Fe^I ClV^V₁₂ O₃₂ Cl]^5- . Experimental and theoretical studies including electron paramagnetic resonance spectroscopy and density functional theory computations verify the formation of the Fe^I species. The study presents the first example for the seemingly paradoxical embedding of low-valent metal species in high-valent metal oxide anions and opens new avenues for reductive electron transfer catalysis by polyoxometalates.

Keywords: electrochemistry; iron; metal oxides; polyoxometalates; self-assembly.

Publication types

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