Photoinduced Isomerization of [N2]2– in a Bimetallic Lutetium Complex

The first lanthanide dinitrogen photoswitch [(C₅Me₄H)₂(THF)Lu]₂(μ–η²:η²-N₂), 1, is reported. 1 is a unique example of controlled isomerization between side-on and end-on coordination modes of [N₂]^2– in a bimetallic lutetium dinitrogen complex that results in photochromism. Near-infrared light (NIR) was used to promote this effect, as evidenced by single X-ray diffraction (XRD) connectivity and Raman data, generating the [N₂]^2– end-on bound isomer, [(C₅Me₄H)₂(THF)Lu]₂(μ–η¹:η¹-N₂), 2. Although different ligands and coordinating solvents were studied to replicate and control the optical properties in 1/2, only the original configuration with C₅Me₄H ligands and THF as the coordinating solvent worked. Supported by the first-principles calculations, the electronic structures along with the mechanistic details of the side-on to end-on isomerization were unraveled. Preliminary reactivity studies show that 2 formed with NIR light reacts with anthracene, generating dihydroanthracene and anthracene dimers, indicating new redox reaction pathways.