Catalytic dehydrocoupling of amine-boranes using cationic zirconium(IV)-phosphine frustrated Lewis pairs

Metters, Owen J., Flynn, Stephanie R., Dowds, Christiana K., Sparkes, Hazel A., Manners, Ian and Wass, Duncan ORCID: https://orcid.org/0000-0002-0356-7067 2016. Catalytic dehydrocoupling of amine-boranes using cationic zirconium(IV)-phosphine frustrated Lewis pairs. ACS Catalysis 6 (10) , pp. 6601-6611. 10.1021/acscatal.6b02211

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Abstract

A series of novel, intramolecular Zr(IV)/P frustrated Lewis pairs (FLPs) based on cationic zirconocene fragments with a variety of ancillary cyclopentadienyl and 2-phosphinoaryloxide (−O(C6H4)PR2, R = tBu and 3,5-CF3-(C6H3)) ligands are reported and their activity as catalysts for the dehydrocoupling of dimethylamine–borane (Me2NH·BH3) assessed. The FLP system [(C9H7)2ZrO(C6H4)PtBu2][B(C6F5)4] is shown to give unprecedented turnover frequencies (TOF) for a catalyst based on a group 4 metal (TOF ≥ 600 h–1), while also proving to be the most efficient FLP catalyst reported to date. The mechanism of this reaction has been probed using analogous intermolecular Zr(IV)/P FLPs, permitting deconvolution of the reactions taking place at both the Lewis acidic and basic sites. Elucidation of this mechanism revealed an interesting cooperative two-cycle process where one cycle is FLP mediated and the other, a redistribution of a linear diborazane intermediate, relies solely on the presence of a Zr(IV) Lewis acid.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Cardiff Catalysis Institute (CCI) Chemistry
Publisher:	American Chemical Society
ISSN:	2155-5435
Date of First Compliant Deposit:	26 October 2018
Date of Acceptance:	9 August 2016
Last Modified:	26 Nov 2024 18:05
URI:	https://orca.cardiff.ac.uk/id/eprint/116207

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