Abstract: This work systematically investigates the coordination and interconversion behaviors of tris(pentafluorophenyl)borane (BCF) with eleven substituted amines in the presence of varying amounts of water, employing 11B/1?F-NMR spectroscopy and theoretical calculations. The catalytic activity of these systems in reactions with phenylsilane was further explored. The results indicate that the amine/BCF/H?O systems primarily exist in three coordination modes: B–N coordination, boronium hydroxide (B–OH) species, and a three-component hydrogen-bonded complex of the type “LB---H—(H)O---LA”. When the molar ratio of H?O reaches or exceeds that of BCF, the coordination equilibrium shifts significantly toward the hydrated three-component form. This shift markedly alters the protonation capability of the substrates and their reactivity in silane reduction, thereby determining the activation pathway with PhSiH?. This study not only provides experimental evidence to elucidate the reaction mechanisms of boranes under aqueous conditions but also offers theoretical and practical guidance for designing and expanding Frustrated Lewis Pairs (FLPs) catalytic systems in aqueous environments.

Key words: Water; Amines, BCF, Lewis acid；Lewis base