B-H Activation by frustrated Lewis pairs: borenium or boryl phosphonium cation?

Catechol boraric reacts svith the frustrated Lewis pairs tBu(2)RP (R = tBu, 2-C6H4(C6H5)) and B(C6F5)(3) to give the species [(C6H4O2)BPtBu2R][HB(C6F5)(3)] that can formally be described as either borenium cation or boryl-phosphonium salts; the nature of these species was probed with DFT calculations.