Concepts for the thermodynamically challenging synthesis of weak N-H bonds by photoinduced proton coupled electron transfer are explored. Upon irradiation with blue light, ammonia synthesis was achieved from the manganese nitride (tBuSalen)MnN (tBuSalen = (S,S)-(+)-N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine) in the presence of 9,10-dihydroacridine and a ruthenium photocatalyst in iPrOH solution. Although in one case the ruthenium complex bears a remote N-H bond that weakens to 41 kcal mol-1 upon irradiation, control experiments with the N-methylated analog demonstrate the ruthenium complex serves as a photoreductant rather than hydrogen-atom transfer catalyst in aprotic solvents. Luminescence quenching experiments support a ruthenium(ii)/(iii) cycle rather than a ruthenium(i)/(ii) alternative. Identification of the manganese complex following ammonia synthesis was also accomplished.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Metals and Alloys
- Materials Chemistry
- Surfaces, Coatings and Films