Orthogonal Photo-Isomerization of Sulfoxide-Chelated Ruthenium Precatalyst

Ruthenium precatalysts have been proven to be very efficient in olefin metathesis reaction due to their stability towards moisture and air, broad functional group tolerance and high modularity. Thus, much attention is devoted to the modification of these precatalysts in order to achieve novel properties.

In our group,¹ a family of latent precatalysts having a sulfur chelated to metal center was developed. These complexes have two isomeric forms that can be switched by irradiation with 350nm light, from the stable inactive cis-dichloro to the active trans-dichloro.

Herein we show the development of chelated ruthenium sulfoxide complexes and the investigation of not just their cis to trans isomerization process, but also from Ru-S=O to Ru-O=S binding mode; as well as the effect of these isomerizations on the reactivity of the complexes. The rationale behind this new family of complexes is based on the studies that show that ruthenium sulfoxide complexes can undergo isomerization from Ru-S=O to Ru-O=S by irradiation by UV light, and the known reduced affinity of oxygen-ruthenium linkages compared to sulfur-ruthenium².

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