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 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 a borderline case of first-order/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.