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The hydride-ion affinity of borenium cations and their propensity to activate H2 in frustrated Lewis pairs

Clark, Ewan R., Del Grosso, Alessandro, Ingleson, Michael J. (2013) The hydride-ion affinity of borenium cations and their propensity to activate H2 in frustrated Lewis pairs. Chemistry - A European Journal, 19 (7). pp. 2462-2466. ISSN 0947-6539. (doi:10.1002/chem.201203318) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
http://www.dx.doi.org/10.1002/chem.201203318

Abstract

A range of frustrated Lewis pairs (FLPs) containing borenium cations have been synthesised. The catechol (Cat)-ligated borenium cation [CatB(PtBu3)]+ has a lower hydride-ion affinity (HIA) than B(C6F5)3. This resulted in H2 activation being energetically unfavourable in a FLP with the strong base PtBu3. However, ligand disproportionation of CatBH(PtBu3) at 100?°C enabled trapping of H2 activation products. DFT calculations at the M06-2X/6-311G(d,p)/PCM (CH2Cl2) level revealed that replacing catechol with chlorides significantly increases the chloride-ion affinity (CIA) and HIA. Dichloro–borenium cations, [Cl2B(amine)]+, were calculated to have considerably greater HIA than B(C6F5)3. Control reactions confirmed that the HIA calculations can be used to successfully predict hydride-transfer reactivity between borenium cations and neutral boranes. The borenium cations [Y(Cl)B(2,6-lutidine)]+ (Y=Cl or Ph) form FLPs with P(mesityl)3 that undergo slow deprotonation of an ortho-methyl of lutidine at 20?°C to form the four-membered boracycles [(CH2{NC5H3Me})B(Cl)Y] and [HPMes3]+. When equimolar [Y(Cl)B(2,6-lutidine)]+/P(mesityl)3 was heated under H2 (4?atm), heterolytic cleavage of dihydrogen was competitive with boracycle formation.

Item Type: Article
DOI/Identification number: 10.1002/chem.201203318
Uncontrolled keywords: borenium cations, boron, density functional calculations, frustrated Lewis pairs, hydrides
Subjects: Q Science > QD Chemistry
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Giles Tarver
Date Deposited: 29 Jul 2015 15:11 UTC
Last Modified: 29 May 2019 14:56 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/49875 (The current URI for this page, for reference purposes)
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