Conjugation in Isomeric Cyclosilane Thioethers

Abstract

Conjugation in thioether-functionalized cyclosilanes depends on both conformation and connectivity. Borane-catalyzed dehydrocoupling of thiophenols with partially hydrogenated cyclosilanes proceeded with high chemoselectivity for Si−H bonds in the presence of Si−Si bonds. Isomeric 1,3and 1,4-functionalized cyclosilanes afforded isomeric cyclosilane thioethers that also differed in preference for chair or twist-boat conformations as demonstrated by both X-ray crystal structures and density functional theory (DFT) calculations. The confounding effects of different conformations and connectivity could be distinguished with time-dependent DFT (TD-DFT) calculations and validated with experimentally obtained UV−vis spectra.