Dehydropolymerization of Amine-Boranes using Bis(imino)pyridine Rhodium Pre-Catalysis: σ-Amine-Borane Complexes, Nanoparticles, and Low Residual-Metal BN-Polymers that can be Chemically Repurposed.

Autor: Cross MJ; Department of Chemistry, University of York, York, YO10 5DD, UK., Brodie CN; Department of Chemistry, University of York, York, YO10 5DD, UK., Crivoi DG; Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK., Goodall JC; Department of Chemistry, University of York, York, YO10 5DD, UK., Ryan DE; Department of Chemistry, University of York, York, YO10 5DD, UK.; Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK., Martínez-Martínez AJ; Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK.; Supramolecular Organometallic and Main Group Chemistry Laboratory CIQSO-Center for Research in Sustainable Chemistry and Department of Chemistry, University of Huelva, Campus El Carmen, 21007, Huelva, Spain., Johnson A; Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK.; Department of Biosciences and Chemistry, Sheffield Hallam University, Howard St, Sheffield, S1 1WB, UK., Weller AS; Department of Chemistry, University of York, York, YO10 5DD, UK.
Jazyk: angličtina
Zdroj: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2023 Oct 26; Vol. 29 (60), pp. e202302110. Date of Electronic Publication: 2023 Sep 21.
DOI: 10.1002/chem.202302110
Abstrakt: The sigma amine-borane complexes [Rh(L1)(η 2 :η 2 -H 3 B⋅NRH 2 )][OTf] (L1=2,6-bis-[1-(2,6-diisopropylphenylimino)ethyl]pyridine, R=Me, Et, n Pr) are described, alongside [Rh(L1)(NMeH 2 )][OTf]. Using R=Me as a pre-catalyst (1 mol %) the dehydropolymerization of H 3 B ⋅ NMeH 2 gives [H 2 BNMeH] n selectively. Added NMeH 2 , or the direct use of [Rh(L1)(NMeH 2 )][OTf], is required for initiation of catalysis, which is suggested to operate through the formation of a neutral hydride complex, Rh(L1)H. The formation of small (1-5 nm) nanoparticles is observed at the end of catalysis, but studies are ambiguous as to whether the catalysis is solely nanoparticle promoted or if there is a molecular homogeneous component. [Rh(L1)(NMeH 2 )][OTf] is shown to operate at 0.025 mol % loadings on a 2 g scale of H 3 B ⋅ NMeH 2 to give polyaminoborane [H 2 BNMeH] n [M n =30,900 g/mol, Ð=1.8] that can be purified to a low residual [Rh] (6 μg/g). Addition of Na[N(SiMe 3 ) 2 ] to [H 2 BNMeH] n results in selective depolymerization to form the eee-isomer of N,N,N-trimethylcyclotriborazane [H 2 BNMeH] 3 : the chemical repurposing of a main-group polymer.
(© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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