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

Stoichiometric reaction of phosphine-borane adducts RR'PH⋅BH 3 (R=Ph, R'=H, Ph, Et, and R=R'= t Bu) with the strong acid HNTf 2 (Tf=SO 2 CF 3 ) leads to H 2 elimination and the formation of the triflimido derivatives, RR'PH⋅BH 2 (NTf 2 ). 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 2 ] n . Evidence for the intermediacy of transient phosphinoborane monomers, RR'PBH 2 , was provided by trapping reactions.