Establishing the Role of Triflate Anions in H Activation by a Cationic Triorganotin(IV) Lewis Acid.

Cationic Lewis acids (LAs) are gaining interest as targets for frustrated Lewis pair (FLP)-mediated catalysis. Unlike neutral boranes, which are the most prevalent LAs for FLP hydrogenations, the Lewis acidity of cations can be tuned through modulation of the counteranion; however, detailed studies on such anion effects are currently lacking in the literature. Herein, we present experimental and computational studies which probe the mechanism of H activation using PrSnOTf (-OTf) in conjunction with a coordinating (quinuclidine; qui) and noncoordinating (2,4,6-collidine; col) base and compare its reactivity with {PrSn·base}{Al[OC(CF)]} (base = qui/col) systems which lack a coordinating anion to investigate the active species responsible for H activation and hence resolve any mechanistic roles for OTf in the PrSnOTf-mediated pathway.