Terminal Hydride Complex of High-Spin Mn

Overview

Journal J Am Chem Soc

Publisher American Chemical Society

Specialty Chemistry

Date 2024 Jun 28

PMID 38940813

Authors

Alex Drena

Addison Fraker

Niklas B Thompson

Peter E Doan

Brian M Hoffman

Alex McSkimming

Affiliations

Soon will be listed here.

Abstract

The iron-molybdenum cofactor of nitrogenase (FeMoco) catalyzes fixation of N via Fe hydride intermediates. Our understanding of these species has relied heavily on the characterization of well-defined 3d metal hydride complexes, which serve as putative spectroscopic models. Although the Fe ions in FeMoco, a weak-field cluster, are expected to adopt locally high-spin Fe configurations, synthetically accessible hydride complexes featuring d or d electron counts are almost exclusively low-spin. We report herein the isolation of a terminal hydride complex of four-coordinate, high-spin (d; = 5/2) Mn. Electron paramagnetic resonance and electron-nuclear double resonance studies reveal an unusually large degree of spin density on the hydrido ligand. In light of the isoelectronic relationship between Mn and Fe, our results are expected to inform our understanding of the valence electronic structures of reactive hydride intermediates derived from FeMoco.

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