J. Cross, C. N. Brodie, D. G. Crivoi, J. C. Goodall, D. E. Ryan, A. J. Martínez-Martínez, A. Johnson, A. S. Weller, Chem. Eur. J. 2023
https://doi.org/10.1002/chem.202302110
Thesigma amine-borane complexes[Rh(L1)(h2:h2-H3B·NRH2)][OTf] (L1= 2,6-bis-[1-(2,6-diisopropylphenylimino)ethyl]-pyridine, R = Me, Et, nPr) are described, alongside [Rh(L1)(NMeH2)]-[OTf]. UsingR = Meas apre-catalyst(1 mol%)the dehydro-polymerization of H3B·NMeH2gives[H2BNMeH]nselectively. AddedNMeH2,or the direct use of [Rh(L1)(NMeH2)][OTf], is required for initiation of catalysis, which is suggested to operate through formation of a neutral hydride complex, Rh(L1)H. The formation of small (1-5nm) nanoparticles is observed at the end ofcatalysis, but studies are ambiguous as to whether the catalysis is solelynanoparticle promoted or if there is a molecular homogeneous component. [Rh(L1)(NMeH2)]-[OTf] is shown to operate at 0.025mol% loadings on a 2 g scale of H3B·NMeH2to give polyaminoborane [H2BNMeH]n[Mn= 30,900 g/mol, Ð = 1.8]that can be purified to alow residual [Rh] (6 μg/g). Addition of Na[N(SiMe3)2] to [H2BNMeH]nresults in selective depolymerization to form the eee-isomer of N,N,N-trimethylcyclotriborazane [H2BNMeH]3: the chemicalrepurposing of a main-group polymer.
