Visible light harvesting alkyne hydrosilylation mediated by pincer platinum complexes

• Published in: Journal of catalysis Vol. 428; p. 115155
• Main Authors: Ibáñez-Ibáñez, Laura, Lázaro, Ariadna, Mejuto, Carmen, Crespo, Margarita, Vicent, Cristian, Rodríguez, Laura, Mata, Jose A.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.12.2023
• Subjects: alkynes; ambient temperature; catalysts; HAT; Hydrosilylation; light; Mechanisms; Photocatalysis; photosensitizing agents; Platinum; reaction mechanisms; species; stereoselectivity; ESI-MS; Mechanisms; Hydrosilylation; HAT; Platinum; Photocatalysis
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2023.115155

Increasing the efficiency of hydrosilylation assisted by visible-light. Catalytic properties and reaction mechanism with the formation of radicals where the platinum complexes play a dual role as harvesting light species and enabling bond breaking/forming transformations. [Display omitted] •Platinum complexes induce alkyne hydrosilylation under photo or thermal conditions.•A single platinum complex plays a dual role as a photosensitizer and a catalyst enabling bond breaking/forming transformations.•Stereodivergent selectivity under photochemical or thermal conditions.•Increased hydrosilylation efficiency under photocatalytic conditions in terms of reduction time, lower temperature and catalyst loadings.•Trapping intermediates by electrospray ionization mass spectrometry evidence the formation of silylradicals as relevant species in the reaction mechanism. In this manuscript we assess the catalytic properties of pincer platinum complexes in alkyne hydrosilylation either under photo or thermal conditions. The visible light-induced hydrosilylation proved to be more efficient. It can be performed at room temperature and required lower catalyst loadings than that operating under thermal conditions. The platinum complexes play a dual role in photohydrosilylation as serve as a photosensitizer and a catalyst enabling species in bond breaking/forming transformations. In addition, alkyne hydrosilylation is achieved with moderate regio- and stereoselectivity but is enhanced under photocatalytic conditions and in the case of terminal alkynes we have observed the formation of β(Z) products not observable under thermal conditions. Such differences in selectivity constitute an example of stereodivergent catalysis dictated under photochemical or thermal conditions. The selectivity differences are ascribed to a distinctive reaction mechanism for the light- vs thermally-induced process that involve radical or organometallic intermediates, respectively.