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

Abstract

Abstract 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 P i Pr 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.