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NO Coupling by Nonclassical Dinuclear Dinitrosyliron Complexes to Form N2O Dictated by Hemilability
Walker R Marks1, Eric W Reinheimer2, Takele Seda3
1Department of Chemistry, Western Washington University, Bellingham, Washington 98225, United States.
Inorganic Chemistry
|September 13, 2021
Summary
Researchers report selective coupling of nitric oxide (NO) using a dinuclear dinitrosyliron complex (D-DNIC) to form nitrous oxide (N2O). The pyridinediimine (PDI) ligand facilitates this reaction by enabling electron-deficient intermediates crucial for N-N bond formation.
Area of Science:
- Inorganic Chemistry
- Organometallic Chemistry
- Catalysis
Background:
- Dinitrosyliron complexes (DNICs) are implicated in biological NO signaling.
- Understanding the reactivity of DNICs is key to developing new catalytic processes.
- Selective transformations of NO are challenging due to its radical nature.
Purpose of the Study:
- To investigate the selective coupling of nitric oxide (NO) by a nonclassical dinuclear dinitrosyliron complex (D-DNIC).
- To elucidate the role of the pyridinediimine (PDI) ligand scaffold in facilitating NO coupling.
- To understand the electronic and structural requirements for N-N bond formation in DNICs.
Main Methods:
- Synthesis and characterization of dinuclear dinitrosyliron complexes featuring a PDI ligand.
- Electrochemical oxidation studies to generate reactive intermediates.
- Spectroscopic analysis to identify reaction products and intermediates.
Main Results:
- Selective coupling of NO to form N2O was achieved with the Fe2(PyrrPDI)(NO)4 complex.
- One-electron oxidation generated a mixed-valent species with an electron-deficient four-coordinate {Fe(NO)2}10 site, crucial for N-N bond formation.
- The hemilability of the PDI ligand controlled the selectivity, preventing N-N coupling in related complexes.
Conclusions:
- The PDI ligand scaffold is essential for facilitating selective NO coupling to N2O.
- Electron-deficient {Fe(NO)2} sites are critical intermediates for N-N bond formation.
- Ligand design in DNICs offers a pathway to control NO reactivity and selectivity.
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