Electro- and photocatalytic hydrogen generation in acetonitrile and aqueous solutions by a cobalt macrocyclic Schiff-base complex

The cobalt(III) macrocyclic Schiff-base complex, [CoIII(CR)Cl]ClO4 (CR = 2,12-dimethyl-3,7,11,17-tetra-azabicyclo[11.3.1]-heptadeca-1(17),2,11,13,15-pentaene), is an active catalyst for the electrocatalytic proton reduction to generate dihydrogen in both acetonitrile and 100% aqueous solution (at −0.57 and −0.85 V vs SCE, respectively), using p-cyanoanilinium tetrafluoroborate and acetic acid as proton sources, respectively. Bulk electrolysis confirmed that dihydrogen is produced with >90% Faradaic yields and >50 TON in both solvents. [CoIII(CR)Cl2]ClO4 also catalyzes photo-driven (λ > 390 nm) hydrogen production in aqueous acetonitrile at TON of 180 (not optimized), using [IrIII(ppy)2(bpy)]PF6 as the photosensitizer, triethanolamine (TEOA) as the sacrificial donor and acetic acid as the proton source.