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Theoretical studies of the oxidative addition of azolium salts to a model Wilkinson's catalyst

journal contribution
posted on 2023-05-16, 15:38 authored by Kirsty HawkesKirsty Hawkes, McGuinness, DS, Cavell, KJ, Brian YatesBrian Yates
The oxidative addition of 1,3-dimethylimidazolium to a model Wilkinson's catalyst (RhCl(PH3)3) has been studied with density functional calculations (B3LYP). According to our free energy calculations, the octahedral rhodium carbene hydride product forms from initial predissociation of a phosphine molecule to subsequently form a 5 ligand intermediate; however, results indicate that a six ligand, associative route with a concerted three-centred transition structure may also be competitive. Exchange of the phosphine molecule on the metal centre with trimethylphosphine had a significant effect in lowering the barrier to oxidative addition and decreasing the endothermicity of the reaction. Solvation was found to have a moderate effect on the overall reaction. Bulk solvent calculations reflected a relative stabilisation of reactants for both pathways, resulting in an endothermic overall reaction. A study of alternative azolium salts revealed the saturated 1,3-dimethy1-4,5-dihydroimidazolium resulted in little change to the reaction geometries or energies, while the use of 3-methylthiazolium salt significantly reduced the barrier to addition and increased the exothermicity of the reaction considerably.

History

Publication title

Dalton Transactions

Issue

16

Pagination

2505-2513

ISSN

1477-9226

Department/School

School of Natural Sciences

Publisher

Royal Society of Chemistry

Place of publication

Cambridge

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the chemical sciences

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