Computational mechanistic insights into feeding sequence-controlled rhodium active catalysts for regio- and stereoselective hydrosilylation of terminal alkyne

• Hydrosilylation mechanism of terminal alkyne catalyzed by rhodium complex in stepwise feeding strategy. • Hydrosilylation mechanism of terminal alkyne catalyzed by rhodium complex in one-step feeding strategy. • Mechanism differences between stepwise and one-step feeding strategies in rhodium complex-catalyzed hydrosilylation of terminal alkyne. • Origins of anti -Markovnikov regioselectivity and E/Z stereoselectivity in rhodium complex-catalyzed hydrosilylation of terminal alkyne under two distinct feeding strategies. DFT calculations were conducted to explore the mechanisms and origins of feeding sequence-controlled divergent selective hydrosilylation of terminal alkyne catalyzed by rhodium complex. The calculation results reveal that varying feeding sequences of reactants (silane and alkyne) lead to the formation of distinct active catalysts, each following a different reaction mechanism. Under a stepwise feeding strategy, the reaction follows a Haszeldine-like mechanism, yielding the anti -Markovnikov anti -addition product, β -( Z )-vinylsilane ( 3a ). In contrast, the one-step feeding process proceeds via the Chalk–Harrod mechanism, producing the anti -Markovnikov syn -addition product, β -( E )-vinylsilane ( 4a ). The observed anti -Markovnikov regioselectivity in both strategies primarily stems from little steric hindrance and the spherical nature of the hydrogen 1 s orbital. The E / Z stereoselectivity is governed by different active catalysts generated through distinct feeding sequences, which in turn govern the reaction pathways and stereoselective outcomes. These mechanistic insights offer a deeper understanding of the title reaction.