Chemical functionality of poly(methylenephosphine): phosphine-borane adducts and methylphosphonium ionomers

The chemical functionality of poly(methylenephosphine) n-Bu[MesP-CPh(2)](n)H (2) is examined in reactions with two isoelectronic species, namely BH(3) and CH(3)(+). The potential reactivity of polymer 2 is modelled by examining the reactivity of molecular phosphines bearing similar substituents as the polymer. In particular, the phosphine - borane adducts Mes(Me)P(BH(3))-CPh(2)H (4a) and Mes(Me)P( BH(3)) - CPh(2)SiMe(2)H (4b) are prepared from the reaction of BH(3) center dot SMe(2) with Mes(Me)P - CPh(2)H (3a) or Mes(Me)P-CPh(2)SiMe(2)H (3b), respectively. Treating 3a with MeOTf affords the methylated model compound, [Mes(Me)(2)P-CPh(2)H]OTf(5). X-Ray crystal structures are reported for each model compound. The reaction of n-Bu[MesP-CPh(2)]nH (Mn = 3.89 x 10(4), PDI = 1.34) with BH(3) center dot SMe2 affords the phosphine - borane polymer n-Bu[MesP(BH(3)) - CPh(2)]nH (6) (Mn = 4.13 x 10(4), PDI = 1.26). In contrast, methylation of phosphine polymer 2 gives n- Bu[MesP-CPh2](x)-/-[MesP(Me) - CPh2](y)H center dot(OTf)(y) (7) where approximately 50% of the phosphine moieties are methylated (from (31)P NMR).