Nonprecious-Metal-Assisted Photochemical Hydrogen Production from ortho-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-phenylenediarnine) iron(II) complex, [Fe-II(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 H-2 production/storage materials.