Proton reduction by phosphinidene-capped triiron clusters
(2021) In Journal of Organometallic Chemistry 943.- Abstract
Bis(phosphinidene)-capped triiron carbonyl clusters, including electron rich derivatives formed by substitution with chelating diphosphines, have been prepared and examined as proton reduction catalysts. Treatment of the known cluster [Fe3(CO)9(µ3-PPh)2] (1) with various diphosphines in refluxing THF (for 5, refluxing toluene) afforded the new clusters [Fe3(CO)7(µ3-PPh)2(κ2-dppb)] (2), [Fe3(CO)7(µ3-PPh)2(κ2-dppv)] (3), [Fe3(CO)7(µ3-PPh)2(κ2-dppe)] (4) and... (More)
Bis(phosphinidene)-capped triiron carbonyl clusters, including electron rich derivatives formed by substitution with chelating diphosphines, have been prepared and examined as proton reduction catalysts. Treatment of the known cluster [Fe3(CO)9(µ3-PPh)2] (1) with various diphosphines in refluxing THF (for 5, refluxing toluene) afforded the new clusters [Fe3(CO)7(µ3-PPh)2(κ2-dppb)] (2), [Fe3(CO)7(µ3-PPh)2(κ2-dppv)] (3), [Fe3(CO)7(µ3-PPh)2(κ2-dppe)] (4) and [Fe3(CO)7(µ3-PPh)2(µ-κ2-dppf)] (5) in moderate yields, together with small amounts of the corresponding [Fe3(CO)8(µ3-PPh)2(κ1-Ph2PxPPh2)] cluster (x = -C4H6-, -C2H2-, -C2H4-, -C3H6-, -C5H4FeC5H4-). The molecular structures of complexes 3 and 5 have been established by X-ray crystallography. Complexes 1–5 have been examined as proton reduction catalysts in the presence of p-toluenesulfonic acid (p-TsOH) in CH2Cl2. Cluster 1 exhibits two one-electron quasi-reversible reduction waves at –1.39 V (ΔE = 195 mV) and at –1.66 V (ΔE = 168 mV; potentials vs. Fc+/Fc). Upon addition of p-TsOH the unsubstituted cluster 1 shows a first catalytic wave at –1.57 V and two further proton reduction processes at –1.75 and –2.29 V, each with a good current response. The diphosphine-substituted derivatives of 1 are reduced at more negative potentials than the parent cluster 1. Clusters 2–4 each exhibit an oxidation at ca. +0.1 V and a reduction at ca. –1.6 V; for 4 conversion to a redox active successor species is seen upon both oxidation and reduction. Clusters 2–4 show catalytic waves in the presence of p-TsOH, with cluster 4 exhibiting the highest relative catalytic current (icat/i0 ≈ 57) in the presence of acid, albeit at a new third reduction process not observed for 2 and 3. Addition of the dppf ligand to the parent diphosphinidene cluster 1 gave cluster 5 which exhibited a single reduction process at –1.95 V and three oxidation processes, all at positive values as compared to 2–4. Cluster 5 showed only weak catalytic activity for proton reduction with p-TsOH. The bonding in 4 was investigated by DFT calculations, and the nature of the radical anion and dianion is discussed with respect to the electrochemical data.
(Less)
- author
- Rahaman, Ahibur LU ; Lisensky, George C. LU ; Haukka, Matti ; Tocher, Derek A. ; Richmond, Michael G. ; Colbran, Stephen B. and Nordlander, Ebbe LU
- organization
- publishing date
- 2021-06-21
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- DFT, Electrocatalysis, Phosphinidine, Proton reduction, Triiron
- in
- Journal of Organometallic Chemistry
- volume
- 943
- article number
- 121816
- publisher
- Elsevier
- external identifiers
-
- scopus:85105116836
- ISSN
- 0022-328X
- DOI
- 10.1016/j.jorganchem.2021.121816
- language
- English
- LU publication?
- yes
- id
- 12eeffbf-a566-4d89-a967-786dbd3ecd2e
- date added to LUP
- 2021-05-26 14:43:00
- date last changed
- 2022-04-27 02:03:30
@article{12eeffbf-a566-4d89-a967-786dbd3ecd2e,
abstract = {{<p>Bis(phosphinidene)-capped triiron carbonyl clusters, including electron rich derivatives formed by substitution with chelating diphosphines, have been prepared and examined as proton reduction catalysts. Treatment of the known cluster [Fe<sub>3</sub>(CO)<sub>9</sub>(µ<sub>3</sub>-PPh)<sub>2</sub>] (1) with various diphosphines in refluxing THF (for 5, refluxing toluene) afforded the new clusters [Fe<sub>3</sub>(CO)<sub>7</sub>(µ<sub>3</sub>-PPh)<sub>2</sub>(κ<sup>2</sup>-dppb)] (2), [Fe<sub>3</sub>(CO)<sub>7</sub>(µ<sub>3</sub>-PPh)<sub>2</sub>(κ<sup>2</sup>-dppv)] (3), [Fe<sub>3</sub>(CO)<sub>7</sub>(µ<sub>3</sub>-PPh)<sub>2</sub>(κ<sup>2</sup>-dppe)] (4) and [Fe<sub>3</sub>(CO)<sub>7</sub>(µ<sub>3</sub>-PPh)<sub>2</sub>(µ-κ<sup>2</sup>-dppf)] (5) in moderate yields, together with small amounts of the corresponding [Fe<sub>3</sub>(CO)<sub>8</sub>(µ<sub>3</sub>-PPh)<sub>2</sub>(κ<sup>1</sup>-Ph<sub>2</sub>PxPPh<sub>2</sub>)] cluster (x = -C<sub>4</sub>H<sub>6</sub>-, -C<sub>2</sub>H<sub>2</sub>-, -C<sub>2</sub>H<sub>4</sub>-, -C<sub>3</sub>H<sub>6</sub>-, -C<sub>5</sub>H<sub>4</sub>FeC<sub>5</sub>H<sub>4</sub>-). The molecular structures of complexes 3 and 5 have been established by X-ray crystallography. Complexes 1–5 have been examined as proton reduction catalysts in the presence of p-toluenesulfonic acid (p-TsOH) in CH<sub>2</sub>Cl<sub>2</sub>. Cluster 1 exhibits two one-electron quasi-reversible reduction waves at –1.39 V (ΔE = 195 mV) and at –1.66 V (ΔE = 168 mV; potentials vs. Fc<sup>+</sup>/Fc). Upon addition of p-TsOH the unsubstituted cluster 1 shows a first catalytic wave at –1.57 V and two further proton reduction processes at –1.75 and –2.29 V, each with a good current response. The diphosphine-substituted derivatives of 1 are reduced at more negative potentials than the parent cluster 1. Clusters 2–4 each exhibit an oxidation at ca. +0.1 V and a reduction at ca. –1.6 V; for 4 conversion to a redox active successor species is seen upon both oxidation and reduction. Clusters 2–4 show catalytic waves in the presence of p-TsOH, with cluster 4 exhibiting the highest relative catalytic current (i<sup>cat</sup>/i<sup>0</sup> ≈ 57) in the presence of acid, albeit at a new third reduction process not observed for 2 and 3. Addition of the dppf ligand to the parent diphosphinidene cluster 1 gave cluster 5 which exhibited a single reduction process at –1.95 V and three oxidation processes, all at positive values as compared to 2–4. Cluster 5 showed only weak catalytic activity for proton reduction with p-TsOH. The bonding in 4 was investigated by DFT calculations, and the nature of the radical anion and dianion is discussed with respect to the electrochemical data.</p>}},
author = {{Rahaman, Ahibur and Lisensky, George C. and Haukka, Matti and Tocher, Derek A. and Richmond, Michael G. and Colbran, Stephen B. and Nordlander, Ebbe}},
issn = {{0022-328X}},
keywords = {{DFT; Electrocatalysis; Phosphinidine; Proton reduction; Triiron}},
language = {{eng}},
month = {{06}},
publisher = {{Elsevier}},
series = {{Journal of Organometallic Chemistry}},
title = {{Proton reduction by phosphinidene-capped triiron clusters}},
url = {{http://dx.doi.org/10.1016/j.jorganchem.2021.121816}},
doi = {{10.1016/j.jorganchem.2021.121816}},
volume = {{943}},
year = {{2021}},
}