Interplay between Terminal and Bridging Diiron Hydrides in Neutral and Oxidized States
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(dpp...
| Veröffentlicht in: | Organometallics. - 1998. - 36(2017), 11 vom: 12. Juni, Seite 2245-2253 |
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| 1. Verfasser: | |
| Weitere Verfasser: | , , , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2017
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| Zugriff auf das übergeordnete Werk: | Organometallics |
| Schlagworte: | Journal Article |
| Zusammenfassung: | 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*FeIII center. In solution, [1(t-H)]+ isomerizes to [1(μ-H)]+, as anticipated by DFT. Reduction of [1(μ-H)]+ by Cp2Co afforded 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. In contrast, protonation of [1(μ-H)]0 yields 0.5 equiv of H2 by a proposed protonation-induced electron transfer process. Isotopic labeling indicates that μ-H/D ligands are inert |
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| Beschreibung: | Date Revised 01.10.2020 published: Print-Electronic Citation Status PubMed-not-MEDLINE |
| ISSN: | 0276-7333 |
| DOI: | 10.1021/acs.organomet.7b00297 |