Abstract
Chemical and electrochemical oxidation or reduction of our recently reported Ir(IV,IV) mono-μ-oxo dimers results in the formation of fully characterized Ir(IV,V) and Ir(III,III) complexes. The Ir(IV,V) dimers are unprecedented and exhibit remarkable stability under ambient conditions. This stability and modest reduction potential of 0.99 V vs NHE is in part attributed to complete charge delocalization across both Ir centers. Trends in crystallographic bond lengths and angles shed light on the structural changes accompanying oxidation and reduction. The similarity of these mono-μ-oxo dimers to our Ir "blue solution" water-oxidation catalyst gives insight into potential reactive intermediates of this structurally elusive catalyst. Additionally, a highly reactive material, proposed to be a Ir(V,V) μ-oxo species, is formed on electrochemical oxidation of the Ir(IV,V) complex in organic solvents at 1.9 V vs NHE. Spectroelectrochemistry shows reversible conversion between the Ir(IV,V) and proposed Ir(V,V) species without any degradation, highlighting the exceptional oxidation resistance of the 2-(2-pyridinyl)-2-propanolate (pyalk) ligand and robustness of these dimers. The Ir(III,III), Ir(IV,IV) and Ir(IV,V) redox states have been computationally studied both with DFT and multiconfigurational calculations. The calculations support the stability of these complexes and provide further insight into their electronic structures.
| Original language | English |
|---|---|
| Pages (from-to) | 9672-9683 |
| Number of pages | 12 |
| Journal | Journal of the American Chemical Society |
| Volume | 139 |
| Issue number | 28 |
| DOIs | |
| Publication status | Published - Jul 19 2017 |
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ASJC Scopus subject areas
- Catalysis
- Chemistry(all)
- Biochemistry
- Colloid and Surface Chemistry
Cite this
Redox Activity of Oxo-Bridged Iridium Dimers in an N,O-Donor Environment : Characterization of Remarkably Stable Ir(IV,V) Complexes. / Sinha, Shashi Bhushan; Shopov, Dimitar Y.; Sharninghausen, Liam S.; Stein, Christopher J.; Mercado, Brandon Q.; Balcells, David; Pedersen, Thomas Bondo; Reiher, Markus; Brudvig, Gary W; Crabtree, Robert H.
In: Journal of the American Chemical Society, Vol. 139, No. 28, 19.07.2017, p. 9672-9683.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Redox Activity of Oxo-Bridged Iridium Dimers in an N,O-Donor Environment
T2 - Characterization of Remarkably Stable Ir(IV,V) Complexes
AU - Sinha, Shashi Bhushan
AU - Shopov, Dimitar Y.
AU - Sharninghausen, Liam S.
AU - Stein, Christopher J.
AU - Mercado, Brandon Q.
AU - Balcells, David
AU - Pedersen, Thomas Bondo
AU - Reiher, Markus
AU - Brudvig, Gary W
AU - Crabtree, Robert H.
PY - 2017/7/19
Y1 - 2017/7/19
N2 - Chemical and electrochemical oxidation or reduction of our recently reported Ir(IV,IV) mono-μ-oxo dimers results in the formation of fully characterized Ir(IV,V) and Ir(III,III) complexes. The Ir(IV,V) dimers are unprecedented and exhibit remarkable stability under ambient conditions. This stability and modest reduction potential of 0.99 V vs NHE is in part attributed to complete charge delocalization across both Ir centers. Trends in crystallographic bond lengths and angles shed light on the structural changes accompanying oxidation and reduction. The similarity of these mono-μ-oxo dimers to our Ir "blue solution" water-oxidation catalyst gives insight into potential reactive intermediates of this structurally elusive catalyst. Additionally, a highly reactive material, proposed to be a Ir(V,V) μ-oxo species, is formed on electrochemical oxidation of the Ir(IV,V) complex in organic solvents at 1.9 V vs NHE. Spectroelectrochemistry shows reversible conversion between the Ir(IV,V) and proposed Ir(V,V) species without any degradation, highlighting the exceptional oxidation resistance of the 2-(2-pyridinyl)-2-propanolate (pyalk) ligand and robustness of these dimers. The Ir(III,III), Ir(IV,IV) and Ir(IV,V) redox states have been computationally studied both with DFT and multiconfigurational calculations. The calculations support the stability of these complexes and provide further insight into their electronic structures.
AB - Chemical and electrochemical oxidation or reduction of our recently reported Ir(IV,IV) mono-μ-oxo dimers results in the formation of fully characterized Ir(IV,V) and Ir(III,III) complexes. The Ir(IV,V) dimers are unprecedented and exhibit remarkable stability under ambient conditions. This stability and modest reduction potential of 0.99 V vs NHE is in part attributed to complete charge delocalization across both Ir centers. Trends in crystallographic bond lengths and angles shed light on the structural changes accompanying oxidation and reduction. The similarity of these mono-μ-oxo dimers to our Ir "blue solution" water-oxidation catalyst gives insight into potential reactive intermediates of this structurally elusive catalyst. Additionally, a highly reactive material, proposed to be a Ir(V,V) μ-oxo species, is formed on electrochemical oxidation of the Ir(IV,V) complex in organic solvents at 1.9 V vs NHE. Spectroelectrochemistry shows reversible conversion between the Ir(IV,V) and proposed Ir(V,V) species without any degradation, highlighting the exceptional oxidation resistance of the 2-(2-pyridinyl)-2-propanolate (pyalk) ligand and robustness of these dimers. The Ir(III,III), Ir(IV,IV) and Ir(IV,V) redox states have been computationally studied both with DFT and multiconfigurational calculations. The calculations support the stability of these complexes and provide further insight into their electronic structures.
UR - http://www.scopus.com/inward/record.url?scp=85024902184&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85024902184&partnerID=8YFLogxK
U2 - 10.1021/jacs.7b04874
DO - 10.1021/jacs.7b04874
M3 - Article
AN - SCOPUS:85024902184
VL - 139
SP - 9672
EP - 9683
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 28
ER -