Dehydropolymerisation of Methylamine Borane and an N‐Substituted Primary Amine Borane Using a PNP Fe Catalyst

Dehydropolymerisation of methylamine borane (H(3)B⋅NMeH(2)) using the well‐known iron amido complex [(PNP)Fe(H)(CO)] (PNP=N(CH(2)CH(2)PiPr(2))(2)) (1) gives poly(aminoborane)s by a chain‐growth mechanism. In toluene, rapid dehydrogenation of H(3)B⋅NMeH(2) following first‐order behaviour as a limiting case of a more general underlying Michaelis–Menten kinetics is observed, forming aminoborane H(2)B=NMeH, which selectively couples to give high‐molecular‐weight poly(aminoborane)s (H(2)BNMeH)(n) and only traces of borazine (HBNMe)(3) by depolymerisation after full conversion. Based on a series of comparative experiments using structurally related Fe catalysts and dimethylamine borane (H(3)B⋅NMe(2)H) polymer formation is proposed to occur by nucleophilic chain growth as reported earlier computationally and experimentally. A silyl functionalised primary borane H(3)B⋅N(CH(2)SiMe(3))H(2) was studied in homo‐ and co‐dehydropolymerisation reactions to give the first examples for Si containing poly(aminoborane)s.