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Title: Interplay between Terminal and Bridging Diiron Hydrides in Neutral and Oxidized States

Abstract

This study describes the structural, spectroscopic, and electrochemical properties of electronically unsymmetrical diiron hydrides. The terminal hydride Cp*Fe(pdt)Fe(dppe)(CO)H ([1(t-H)]0, Cp*– = Me5C5 –, pdt2– = CH2(CH2S–)2, dppe = Ph2PC2H4PPh2) was prepared by hydride reduction of [Cp*Fe(pdt)Fe(dppe)(CO)(NCMe)]+. As established by X-ray crystallography, [1(t- H)]0 features a terminal hydride ligand. Unlike previous examples of terminal diiron hydrides, [1(t-H)]0 does not isomerize to the bridging hydride [1(µ-H)]0. Oxidation of [1(t-H)]0 gives [1(t- H)]+, which was also characterized crystallographically as its BF4 – salt. Density functional theory (DFT) calculations indicate that [1(t-H)]+ is best described as containing an Cp*Fe(III) center. In solution, [1(t-H)]+ isomerizes to [1(µ-H)]+ as anticipated by DFT. Reduction of [1(µ- H)]+ by Cp2Co affords the diferrous bridging hydride [1(µ-H)]0. Electrochemical measurements and DFT calculations indicate that the couples [1(t-H)]+/0 and [1(µ-H)]+/0 differ by 210 mV. Qualitative measurements indicate that [1(t-H)]0 and [1(µ-H)]0 are close in free energy. Protonation of [1(t-H)]0 in MeCN solution affords H2 even with weak acids via hydride transfer.

Authors:
 [1];  [1];  [1];  [2];  [2];  [2];  [2]
  1. Shandong University
  2. University of Illinois at Urbana-Champaign
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1572656
Report Number(s):
PNNL-SA-125689
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Organometallics
Additional Journal Information:
Journal Volume: 36; Journal Issue: 11
Country of Publication:
United States
Language:
English

Citation Formats

Yu, Xin, Tung, Chen-Ho, Wang, Wenguang, Huynh, Mioy T., Gray, Danielle L., Hammes-Schiffer, Sharon, and Rauchfuss, Thomas B. Interplay between Terminal and Bridging Diiron Hydrides in Neutral and Oxidized States. United States: N. p., 2017. Web. doi:10.1021/acs.organomet.7b00297.
Yu, Xin, Tung, Chen-Ho, Wang, Wenguang, Huynh, Mioy T., Gray, Danielle L., Hammes-Schiffer, Sharon, & Rauchfuss, Thomas B. Interplay between Terminal and Bridging Diiron Hydrides in Neutral and Oxidized States. United States. doi:10.1021/acs.organomet.7b00297.
Yu, Xin, Tung, Chen-Ho, Wang, Wenguang, Huynh, Mioy T., Gray, Danielle L., Hammes-Schiffer, Sharon, and Rauchfuss, Thomas B. Mon . "Interplay between Terminal and Bridging Diiron Hydrides in Neutral and Oxidized States". United States. doi:10.1021/acs.organomet.7b00297.
@article{osti_1572656,
title = {Interplay between Terminal and Bridging Diiron Hydrides in Neutral and Oxidized States},
author = {Yu, Xin and Tung, Chen-Ho and Wang, Wenguang and Huynh, Mioy T. and Gray, Danielle L. and Hammes-Schiffer, Sharon and Rauchfuss, Thomas B.},
abstractNote = {This study describes the structural, spectroscopic, and electrochemical properties of electronically unsymmetrical diiron hydrides. The terminal hydride Cp*Fe(pdt)Fe(dppe)(CO)H ([1(t-H)]0, Cp*– = Me5C5 –, pdt2– = CH2(CH2S–)2, dppe = Ph2PC2H4PPh2) was prepared by hydride reduction of [Cp*Fe(pdt)Fe(dppe)(CO)(NCMe)]+. As established by X-ray crystallography, [1(t- H)]0 features a terminal hydride ligand. Unlike previous examples of terminal diiron hydrides, [1(t-H)]0 does not isomerize to the bridging hydride [1(µ-H)]0. Oxidation of [1(t-H)]0 gives [1(t- H)]+, which was also characterized crystallographically as its BF4 – salt. Density functional theory (DFT) calculations indicate that [1(t-H)]+ is best described as containing an Cp*Fe(III) center. In solution, [1(t-H)]+ isomerizes to [1(µ-H)]+ as anticipated by DFT. Reduction of [1(µ- H)]+ by Cp2Co affords the diferrous bridging hydride [1(µ-H)]0. Electrochemical measurements and DFT calculations indicate that the couples [1(t-H)]+/0 and [1(µ-H)]+/0 differ by 210 mV. Qualitative measurements indicate that [1(t-H)]0 and [1(µ-H)]0 are close in free energy. Protonation of [1(t-H)]0 in MeCN solution affords H2 even with weak acids via hydride transfer.},
doi = {10.1021/acs.organomet.7b00297},
journal = {Organometallics},
number = 11,
volume = 36,
place = {United States},
year = {2017},
month = {6}
}

Works referencing / citing this record:

Electrochemical Proton Reduction Catalyzed by [Fe 2 (CO) 6 {μ-(TeCH 2 Te)}] Model that Mimics the Structure of the Active Site of [FeFe]-Hydrogenase : Electrochemical Proton Reduction Catalyzed by [Fe
journal, May 2018

  • Abul-Futouh, Hassan; Görls, Helmar; Weigand, Wolfgang
  • Zeitschrift für anorganische und allgemeine Chemie, Vol. 644, Issue 24
  • DOI: 10.1002/zaac.201800070

Synthetic [NiFe] models with a fluxional CO ligand
journal, January 2017

  • Chu, Xiaoxiao; Yu, Xin; Raje, Sakthi
  • Dalton Trans., Vol. 46, Issue 40
  • DOI: 10.1039/c7dt02892j

Protonation and electrochemical properties of a bisphosphide diiron hexacarbonyl complex bearing amino groups on the phosphide bridge
journal, January 2019

  • Shimamura, Takehiko; Maeno, Yuki; Kubo, Kazuyuki
  • Dalton Transactions, Vol. 48, Issue 44
  • DOI: 10.1039/c9dt03427g

The effect of a pendant amine in phosphine ligand on the structure and electrochemical property of diiron dithiolate complexes
journal, September 2018