Intramolecular heterolytic dihydrogen cleavage by a bifunctional frustrated pyrazolylborane Lewis pair

Abstract

The reaction of bis(pentafluorophenyl)borane, HB(C(6)F(5))(2), with 3,5-di-tert-butyl-1H-pyrazole (3) affords the zwitterionic pyrazolium-borate trans-5 and, after dehydrogenation by use of the frustrated carbene-borane Lewis pair 1/B(C(6)F(5))(3), the bifunctional pyrazolylborane 6, which is able to cleave dihydrogen heterolytically with the formation of a mixture of cis-5 and trans-5.