The first electron-rich sulfoxide-chelated ruthenium complex: A novel entry to s-chelated photo-latent olefin metathesis catalysis

Latent ruthenium benzylidenes having a chelating thioether typically appear in two interchangeable isomeric forms: a thermodynamically more stable inactive cis-dichloro geometry and an active trans-dichlorogeometry accessed by irradiation with 350nm light.¹ However, oxidation of the thioether to sulfoxide produced complexes exclusively in the more typical trans-dichloro form.²The change in the stereochemical preference can be explained by a reduction in the ability of the sulfoxide sulfur atom to donate sigma electron density to the metal center compared to the thioether sulfur atom.³

Herein we show the synthesis and study of electron rich sulfoxide chelated ruthenium complexes that are more stable as the cis-dichloro isomer and the investigation of their uniquephotochemistry. The reactivity of the complexes is also presented. Thus, these novel ruthenium sulfoxide complexes can undergo isomerization from Ru-S=O to Ru-O=S by irradiation with UV light, and present an original activation mechanism based on the known reduced affinity of oxygen-ruthenium linkages compared to sulfur-ruthenium bonding.⁴

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,Organometallics2009, 28, 2693. [b] K. Zukowska, L. Paczek, K. Grela,ChemCatChem, 2016, 8, 2817.

³ Diesendruck, C. E.; Tzur, E.; Ben-Asuly, A.; Vidavsky, Y.; Goldberg, I.; Straub, B. F. and Lemcoff, N. G. Inorg. Chem., 2009,48, 10819.

⁴ B. A. McClure, J. J. Rack,Angew. Chem. Int. Ed., 2009, 48, 8556.