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Updated: Jan 15, 2026

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
Water-Soluble Rhenium Nitride Complexes Supported by Multidentate Phosphinite Ligands Provide Insights into Aqueous
Noah D McMillion1, Mehrnaz Aliahmadi1, Quinton J Bruch1
1Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States.
Abstract:
Metal nitride complexes are key intermediates in ammonia synthesis. Although water would be an ideal source of protons, the synthesis of ammonia from well-defined nitride complexes in water is underexplored. The aqueous reactivity of rhenium nitride complexes supported by tridentate and tetradentate phosphinite-based ligands is examined here. The tetradentate ligand 2,9-bis(diisopropylphosphinitomethyl)-1,10-phenanthroline (6POphenOP) was found to support a nitride complex that is water-soluble and resists ligand hydrolysis from pH 2-13. Structural analysis enabled by hanging-drop crystallization was combined with NMR spectroscopic analysis to elucidate how the rhenium coordination sphere changes when dissolved in aqueous buffer and to identify networks of water molecules in the solid state, including an example of water hydrogen bonding with the nitride. Addition of SmI2 to buffered water solutions of (6POphenOP)Re nitride complexes produced aqueous ammonium. Buffer concentration influences ammonium yields, an effect that is proposed to arise from coordination of buffer to Re and/or Sm, providing insight into the selection of appropriate conditions for aqueous N2 fixation.
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