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Terminal Hydride Complex of High-Spin Mn.

ABSTRACT: The iron-molybdenum cofactor of nitrogenase (FeMoco) catalyzes fixation of N₂ 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^2+/3+ configurations, synthetically accessible hydride complexes featuring d⁵ or d⁶ electron counts are almost exclusively low-spin. We report herein the isolation of a terminal hydride complex of four-coordinate, high-spin (d⁵; S = 5/2) Mn²⁺. 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 Mn²⁺ and Fe³⁺, our results are expected to inform our understanding of the valence electronic structures of reactive hydride intermediates derived from FeMoco.

SUBMITTER: Drena A

PROVIDER: S-EPMC11240256 | biostudies-literature | 2024 Jul

REPOSITORIES: biostudies-literature

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Terminal Hydride Complex of High-Spin Mn.

Drena Alex A Fraker Addison A Thompson Niklas B NB Doan Peter E PE Hoffman Brian M BM McSkimming Alex A

Journal of the American Chemical Society 20240628 27

The iron-molybdenum cofactor of nitrogenase (FeMoco) catalyzes fixation of N2 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 Fe2+/3+ configurations, synthetically accessible hydride complexes featuring d5 or d6 ...[more]

PMID: 38940813

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