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

ABSTRACT

Stoichiometric reaction of phosphine-borane adducts RR'PH⋅BH3 (R=Ph, R'=H, Ph, Et, and R=R'=t Bu) with the strong acid HNTf2 (Tf=SO2 CF3 ) leads to H2 elimination and the formation of the triflimido derivatives, RR'PH⋅BH2 (NTf2 ). 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-BH2 ]n . Evidence for the intermediacy of transient phosphinoborane monomers, RR'PBH2 , was provided by trapping reactions.