Reversible dehydrogenation of a primary aryl borane

Abstract

The consecutive activation of B–H bonds in mesitylborane (H₂BMes; Mes = 2,4,6-(CH₃)₃C₆H₂) by a 16-electron rhodium(I) monocarbonyl complex, (^iPrNNN)Rh(CO) (1-CO; ^iPrNNN = 2,5-[ⁱPr₂PN(4-ⁱPrC₆H₄)]₂N(C₄H₂)⁻) is described. Dehydrogenative extrusion of the {BMes} fragment led to the isolation of (^iPrNNN)(CO)RhBMes (1-BMes). Addition of H₂ gas to 1-BMes regenerated 1-CO and H₂BMes, highlighting the ability of 1-CO to facilitate interconversion of {BMes} with dihydrogen. Reactivity studies revealed that 1-BMes promotes formal group transfer and that {BAr} fragments accessed by dehydrogenation are reactive entities.