Catching the first oligomerization event in the catalytic formation of polyaminoboranes: H3B·NMeHBH2·NMeH2 bound to iridium.

We report the first insertion step at a metal center for the catalytic dehydropolymerization of H(3)B·NMeH(2) to form the simplest oligomeric species, H(3)B·NMeHBH(2)·NMeH(2), by the addition of 1 equiv of H(3)B·NMeH(2) to [Ir(PCy(3))(2)(H)(2)(η(2)-H(3)B·NMeH(2))][BAr(F)(4)] to give [Ir(PCy(3))(2)(H)(2)(η(2)-H(3)B·NMeHBH(2)·NMeH(2))][BAr(F)(4)]. This reaction is also catalytic for the formation of the free linear diborazane, but this is best obtained by an alternative stoichiometric synthesis.