Transition-Metal-Free Dehydropolymerization of Phosphine-Boranes at Ambient Temperature.

Stoichiometric reaction of phosphine-borane adducts RR'PH⋅BH (R=Ph, R'=H, Ph, Et, and R=R'= Bu) with the strong acid HNTf (Tf=SO CF ) leads to H elimination and the formation of the triflimido derivatives, RR'PH⋅BH (NTf ). Subsequent deprotonation by using bases, such as diisopropylethylamine or the carbene IPr (IPr=N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), led to the formation of P-mono- or -disubstituted polyphosphinoboranes [RR'P-BH ] . Evidence for the intermediacy of transient phosphinoborane monomers, RR'PBH , was provided by trapping reactions.