Mono‐ and Dimetallic [Mn(CO)₃] Complexes with the Iminopyridine Ligand for Both Hydrogen and Syngas Productions

Abstract The present study reports the synthesis and structural characterization of two novel mono‐ and dimetallic tricarbonyl manganese(I) complexes with an acenaphthene‐based iminopyridine ligand. The investigation revealed that ligand‐centered reduction occurred for the monometallic complex, while Mn‐centered reduction was observed for the dimetallic complex, both at the first reduction peak potentials. This determination was made through a combination of cyclic voltammetry, bulk electrolysis, and electron paramagnetic resonance spectroscopy. The study further explores the ability of both complexes as catalysts for the CO 2 reduction reaction (CO 2 RR) and hydrogen evolution reaction (HER). The monometallic complex exhibited a 400‐mV gain in overpotential and an 80 to 12 turnover number (TON) advantage over the dimetallic complex for CO 2 RR, with 2,2,2‐trifluoroethanol serving as the proton source. The monometallic Mn I complex demonstrates notable stability in acidic media, exhibiting a high turnover frequency of 2400 s −1 and a TON of 450 in HER.