Group 13 ion coordination to pyridyl models NAD+ reduction potentials

Abstract

N-alkylation and N-metallation of pyridine are explored herein to understand how metal-ligand complexes can model NAD⁺ redox chemistry. Syntheses of substituted dipyrazolylpyridine (pz₂P) compounds (pz₂P)Me⁺ (1⁺) and (pz₂P)GaCl₂⁺ (2⁺) are reported, and compared with (pz₂P)AlCl₂(THF)⁺ and transition element pz₂P complexes from previous reports. Cyclic voltammetry measurements of cationic 1⁺ and 2⁺ show irreversible reduction events ∼900 mV anodic those for neutral pz₂P complexes of divalent metals. We proposed that N-metallation using Group 13 ions of 3+ charge provides an electrochemical model for N-alkylated pyridyls like NAD⁺.