New Photosensitizers Based on Heteroleptic Cu(I) Complexes and CO(2) Photocatalytic Reduction with [Ni(II)(cyclam)]Cl(2)

Earth‐abundant metal complexes have been attracting increasing attention in the field of photo(redox)catalysis. In this work, the synthesis and full characterisation of four new heteroleptic Cu(I) complexes are reported, which can work as photosensitizers. The complexes bear a bulky diphosphine (DPEPhos=bis[(2‐diphenylphosphino)phenyl] ether) and a diimine chelating ligand based on 1‐benzyl‐4‐(quinol‐2′yl)‐1,2,3‐triazole. Their absorption has a relative maximum in the visible‐light region, up to 450 nm. Thus, their use in photocatalytic systems for the reduction of CO(2) with blue light in combination with the known catalyst [Ni(II)(cyclam)]Cl(2) was tested. This system produced CO as the main product through visible light (λ=420 nm) with a TON up to 8 after 4 hours. This value is in line with other photocatalytic systems using the same catalyst. Nevertheless, this system is entirely noble‐metal free.