Latent Ruthenium Benzylidene Phosphite Complexes for Visible-Light-Induced Olefin Metathesis

Herein we report two ruthenium benzylidene complexes with benzylphosphite ligands for olefin metathesis. Unlike the previously reported benzylidene phosphite complexes, the benzylphosphite complexes adopt a cis-dichloro configuration making them latent at ambient temperatures. Irradiation with visible light (420 nm and blue LED) prompts activation of the complexes and induces catalysis of olefin metathesis reactions. One of the complexes, cis-Ru-1, was found to be especially suitable for 3D printing of multilayered polydicyclopentadiene structures with excellent spatial resolutions. Additionally, complex cis-Ru-2 was designed with a chromatic orthogonal “kill switch” based on the 2-nitrobenzyl chemistry, allowing the destruction of the catalyst upon exposure to UV-C light.