Hydrogen Bonding to a Dinitrogen Complex at Room Temperature: Impacts on N2 Activation

We report an experimental and computational analysis of the effects of hydrogen bonding to a metal dinitrogen complex. A series of H-bond donors over a wide pKa range (Δ 20) interact with the nitrogen unit of a ReI-(N2) complex at room temperature. Analysis by 15N NMR, IR spectroscopy, association equilibria, and DFT studies indicates that the H-bonding interaction polarizes and weakens the N–N bond. These results provide insight into the role of the secondary sphere residues in nitrogenase enzymes.