Photo-Isomerization of an Electron Rich Sulfoxide-Chelated Ruthenium Precatalyst

Latent olefin metathesis precatalysts having a sulfur chelated to the metal center typically appear in two isomeric forms: a stable inactive cis-dichloro complex that can be swithched to the active trans-dichloro precatalyst by irradiation with 350nm light.¹ However, sulfoxide chelated complexes, akin to the oxygen chelated complexes, have only been found in their active trans-dichloro geometry.²

Herein we detail the synthesis and study of chelated ruthenium electron rich sulfoxide complexes that are more stable as the latent cis-dichloro isomer and the investigation of not just their cis to trans isomerization process, but also from a Ru-S=O to a Ru-O=S binding mode. The reactivity of the complexes is also presented. Thus, these novel ruthenium sulfoxide complexes can undergo isomerization by UV light and present an original activation mechanism due to the known reduced affinity of oxygen-ruthenium linkages compared to the stronger sulfur-ruthenium bonds.³

References:

¹ [a] A. Ben-Asuly, E. Tzur, C. E. Diesendruck, M. Sigalov, I. Goldberg, N. G. Lemcoff, Organometallics, 2008, 27, 811. [b] A. Ben-Asuly, A. Aharoni, C. E. Diesendruck, Y. Vidavsky, M. Sigalov, I. Goldberg, N. G. Lemcoff, Organometallics, 2009, 28, 4652.

² [a] A. Szadowska, A. Makal, K. Wozniak, R. Kadyrov, K. Grela, Organometallics 2009, 28, 2693. [b] K. Zukowska, L. Paczek, K. Grela, ChemCatChem, 2016, 8, 2817.

³ B. A. McClure, J. J. Rack, Angew. Chem. Int. Ed., 2009, 48, 8556.