Nonprecious-Metal-Assisted Photochemical Hydrogen Production from <i>ortho</i>-Phenylenediamine

The combination of o-phenylenediamine (opda), which possesses two proton- and electron-pooling capability, with Fe­(II) leads to the photochemical hydrogen-evolution reaction (HER) in THF at room temperature without addition of photosensitizers. From the THF solution, the tris­(o-phenylenediamine) iron­(II) complex, [FeII(opda)3]­(ClO4)2 (1), was isolated as a photoactive species, while the deprotonated oxidized species was characterized by X-ray crystallographic analysis, electrospray ionization mass spectrometry, and UV–vis NIR spectra. Furthermore, the HER is photocatalyzed by hydroquinone, which serves as a H+/e– donor. The present work demonstrates that the use of a metal-bound aromatic amine as a H+/e– pooler opens an alternative strategy for designing nonprecious-metal-based molecular photochemical H2 production/storage materials.