Studies on the Activation and Hydrosilylation Catalysis of RhCl₃(Bu₂S)₃

Abstract

RhCl(BuS) is an industrial precatalyst utilized in the curing of some solventless silicone-release coatings formulations. The catalyst requires no additional inhibitor, in contrast to typical Pt formulations, and so questions arose about how fast the catalyst could trigger curing if it were used in a more activated form. Studies on the activation of RhCl(BuS) revealed multiple intermediates, of which [RhCl(BuS)] and [RhHCl(SiMe(OSiMe)) (BuS)] were isolated. [RhHCl(SiMe(OSiMe))(BuS)] is the most activated form of the precatalyst, showing a brief induction period. Various experiments were performed to analyze the nature of the catalyst, including Hg poisoning, addition of poison ligands, and comparisons versus Rh nanoparticles. The data tend to be more consistent with a molecular catalyst than Rh nanoparticles. Data are also provided that support the active catalyst containing a RhCl(BuS) fragment, although the exact identity of the active catalyst is not yet determined.