Dihydrogen Activation with ^<i>t</i>Bu₃P/B(C₆F₅)₃: A Chemically Competent Indirect Mechanism via in Situ-Generated <i>p</i>-^<i>t</i>Bu₂P–C₆F₄–B(C₆F₅)₂

Abstract

A chemically competent indirect pathway for the activation of dihydrogen by the nonmetal Lewis acid/Lewis base pair ^<i>t</i>Bu₃P/B(C₆F₅)₃ is described. The reaction between ^<i>t</i>Bu₃P and B(C₆F₅)₃ produces [^<i>t</i>Bu₃PH]⁺[FB(C₆F₅)₃]⁻ and the known phosphinoborane <i>p</i>-^<i>t</i>Bu₂P–C₆F₄–B(C₆F₅)₂ (<b>1-</b>^{<i><b>t</b></i>}<b>Bu</b>) with elimination of isobutylene. At 1:1 stoichiometry, <b>1-</b>^{<i><b>t</b></i>}<b>Bu</b> is produced rapidly in detectable quantities and can act as a catalyst for the formation of [^<i>t</i>Bu₃PH]⁺[HB(C₆F₅)₃]⁻ from ^<i>t</i>Bu₃P and B(C₆F₅)₃ in the presence of H₂. The extent to which this indirect path competes with the direct path is explored.