English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Fe-mediated biological nitrogen fixation is thought to proceed via either a sequence of proton and electron transfer steps, concerted H atom transfer steps, or some combination thereof. Regardless of the specifics and whether the intimate mechanism for N 2 -to-NH 3 conversion involves a distal pathway, an alternating pathway, or some hybrid of these limiting scenarios, Fe-N x H y intermediates are implicated that feature reactive N-H bonds. Thermodynamic knowledge of the N-H bond strengths of such species is scant, and is especially difficult to obtain for the most reactive early stage candidate intermediates (e.g., Fe-N═NH, Fe═N-NH 2 , Fe-NH═NH). Such knowledge is essential to considering various mechanistic hypotheses for biological (and synthetic) nitrogen fixation and to the rational design of improved synthetic N 2 fixation catalysts. We recently reported several reactive complexes derived from the direct protonation of Fe-N 2 and Fe-CN species at the terminal N atom (e.g., Fe═N-NH 2 , Fe-C≡NH, Fe≡C-NH 2 ). These same Fe-N 2 and Fe-CN systems are functionally active for N 2 -to-NH 3 and CN-to-CH 4 /NH 3 conversion, respectively, when subjected to protons and electrons, and hence provide an excellent opportunity for obtaining meaningful N-H bond strength data. We report here a combined synthetic, structural, and spectroscopic/analytic study to estimate the N-H bond strengths of several species of interest. We assess the reactivity profiles of species featuring reactive N-H bonds and estimate their homolytic N-H bond enthalpies (BDE N-H ) via redox and acidity titrations. Very low N-H bond dissociation enthalpies, ranging from 65 (Fe-C≡NH) to ≤37 kcal/mol (Fe-N═NH), are determined. The collective data presented herein provide insight into the facile reactivity profiles of early stage protonated Fe-N 2 and Fe-CN species.

N–H Bond Dissociation Enthalpies and Facile H Atom Transfers for Early Intermediates of Fe–N2 and Fe–CN Reductions

N–H Bond Dissociation Enthalpies and Facile H Atom Transfers for Early Intermediates of Fe–N₂ and Fe–CN Reductions