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Step-growth titanium-catalysed dehydropolymerisation of amine–boranes

Precatalysts active for the dehydropolymerisation of primary amine–boranes are generally based on mid or late transition metal. We have found that the activity of the precatalyst system formed from Cp(R)(2)TiCl(2) and 2nBuLi towards the dehydrogenation of the secondary amine–borane Me(2)NH·BH(3), to...

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Autores principales: Jurca, Titel, Dellermann, Theresa, Stubbs, Naomi E., Resendiz-Lara, Diego A., Whittell, George R., Manners, Ian
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Royal Society of Chemistry 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5933219/
https://www.ncbi.nlm.nih.gov/pubmed/29780466
http://dx.doi.org/10.1039/c7sc05395a
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author Jurca, Titel
Dellermann, Theresa
Stubbs, Naomi E.
Resendiz-Lara, Diego A.
Whittell, George R.
Manners, Ian
author_facet Jurca, Titel
Dellermann, Theresa
Stubbs, Naomi E.
Resendiz-Lara, Diego A.
Whittell, George R.
Manners, Ian
author_sort Jurca, Titel
collection PubMed
description Precatalysts active for the dehydropolymerisation of primary amine–boranes are generally based on mid or late transition metal. We have found that the activity of the precatalyst system formed from Cp(R)(2)TiCl(2) and 2nBuLi towards the dehydrogenation of the secondary amine–borane Me(2)NH·BH(3), to yield the cyclic diborazane [Me(2)N–BH(2)](2), increases dramatically with increasing electron-donating character of the cyclopentadienyl rings (Cp(R)). Application of the most active precatalyst system (Cp(R) = η-C(5)Me(5)) to the primary amine–borane MeNH(2)·BH(3) enabled the first synthesis of high molar mass poly(N-methylaminoborane), [MeNH–BH(2)](n), the BN analogue of polypropylene, by an early transition metal such as catalyst. Significantly, unlike other dehydropolymerization precatalysts for MeNH(2)·BH(3) such as [Ir(POCOP)H(2)], skeletal nickel, and [Rh(COD)Cl](2), the Ti precatalyst system was also active towards a range of substrates including BzNH(2)·BH(3) (Bz = benzyl) yielding high molar mass polymer. Moreover, in contrast to the late transition metal catalysed dehydropolymerisation of MeNH(2)·BH(3) and also the Ziegler–Natta polymerisation of olefins, studies indicate that the Ti-catalyzed dehydropolymerization reactions proceed by a step-growth rather than a chain-growth mechanism.
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spelling pubmed-59332192018-05-18 Step-growth titanium-catalysed dehydropolymerisation of amine–boranes Jurca, Titel Dellermann, Theresa Stubbs, Naomi E. Resendiz-Lara, Diego A. Whittell, George R. Manners, Ian Chem Sci Chemistry Precatalysts active for the dehydropolymerisation of primary amine–boranes are generally based on mid or late transition metal. We have found that the activity of the precatalyst system formed from Cp(R)(2)TiCl(2) and 2nBuLi towards the dehydrogenation of the secondary amine–borane Me(2)NH·BH(3), to yield the cyclic diborazane [Me(2)N–BH(2)](2), increases dramatically with increasing electron-donating character of the cyclopentadienyl rings (Cp(R)). Application of the most active precatalyst system (Cp(R) = η-C(5)Me(5)) to the primary amine–borane MeNH(2)·BH(3) enabled the first synthesis of high molar mass poly(N-methylaminoborane), [MeNH–BH(2)](n), the BN analogue of polypropylene, by an early transition metal such as catalyst. Significantly, unlike other dehydropolymerization precatalysts for MeNH(2)·BH(3) such as [Ir(POCOP)H(2)], skeletal nickel, and [Rh(COD)Cl](2), the Ti precatalyst system was also active towards a range of substrates including BzNH(2)·BH(3) (Bz = benzyl) yielding high molar mass polymer. Moreover, in contrast to the late transition metal catalysed dehydropolymerisation of MeNH(2)·BH(3) and also the Ziegler–Natta polymerisation of olefins, studies indicate that the Ti-catalyzed dehydropolymerization reactions proceed by a step-growth rather than a chain-growth mechanism. Royal Society of Chemistry 2018-03-06 /pmc/articles/PMC5933219/ /pubmed/29780466 http://dx.doi.org/10.1039/c7sc05395a Text en This journal is © The Royal Society of Chemistry 2018 http://creativecommons.org/licenses/by/3.0/ This article is freely available. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0)
spellingShingle Chemistry
Jurca, Titel
Dellermann, Theresa
Stubbs, Naomi E.
Resendiz-Lara, Diego A.
Whittell, George R.
Manners, Ian
Step-growth titanium-catalysed dehydropolymerisation of amine–boranes
title Step-growth titanium-catalysed dehydropolymerisation of amine–boranes
title_full Step-growth titanium-catalysed dehydropolymerisation of amine–boranes
title_fullStr Step-growth titanium-catalysed dehydropolymerisation of amine–boranes
title_full_unstemmed Step-growth titanium-catalysed dehydropolymerisation of amine–boranes
title_short Step-growth titanium-catalysed dehydropolymerisation of amine–boranes
title_sort step-growth titanium-catalysed dehydropolymerisation of amine–boranes
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5933219/
https://www.ncbi.nlm.nih.gov/pubmed/29780466
http://dx.doi.org/10.1039/c7sc05395a
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