NCT01138540.

Earth-abundant metal complexes have been attracting increasinga ttention 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 ab ulky diphosphine (DPEPhos = bis[(2-diphenylphosphino)phenyl] ether) and ad iimine chelating ligand based on 1-benzyl-4-(quinol-2'yl)-1,2,3-triazole. Their absorption has ar elative maximum in the visible-light region, up to 450 nm. Thus, their use in photocatalytic systemsf or the reduction of CO 2 with blue light in combination with the known catalyst [Ni II (cyclam)]Cl 2 was tested.T his system produced CO as the main product through visible light (l = 420 nm) with aT ON up to 8a fter 4hours. This value is in line with other photocatalytic systemsu sing the same catalyst. Nevertheless, this system is entirely noble-metal free.

This article is dedicated to the memory of our esteemed colleague Markus Gerhards.

Four new heteroleptic Cu(I) complexes based on 1, 2, 3‐triazolyl‐quinoline or quinoxaline and a chelating diphosphine were prepared and fully characterised. The mononuclear derivatives absorb in the visible region, up to 600 nm, while the dinuclear complex has a long‐tail absorption up to 800 nm, showing an additional electronic state corroborated by theoretical calculations. Although a methylene group between the triazole and the quino(xa)line moiety increases the bite angle and decreases the luminescence in solution, all complexes emit brightly in the solid‐state. Their redox properties in the excited state were determined, proving their ability in serving as photoredox catalysts in atom transfer radical addition successfully.

Heteroleptic copper(I) complexes, with a diimine as a chromophoric unit and a bulky diphosphine as an ancillary ligand, have the advantage of a reduced pseudo Jahn-Teller effect in their excited-state...