Mechanistic investigations of the Fe(ii) mediated synthesis of squaraines

Liu, Yu, Coles, Nathan T. ORCID: https://orcid.org/0000-0001-6190-9080, Cajiao, Nathalia, Taylor, Laurence J., Davies, E. Stephen, Barbour, Alistair, Morgan, Patrick J., Butler, Kevin, Pointer-Gleadhill, Ben, Argent, Stephen P., McMaster, Jonathan, Neidig, Michael L., Robinson, David and Kays, Deborah L. ORCID: https://orcid.org/0000-0002-4616-6001 2024. Mechanistic investigations of the Fe(ii) mediated synthesis of squaraines. Chemical Science 15 (25) , pp. 9599-9611. 10.1039/D4SC01286K

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Abstract

The scission and homologation of CO is a fundamental process in the Fischer–Tropsch reaction. However, given the heterogeneous nature of the catalyst and forcing reaction conditions, it is difficult to determine the intermediates of this reaction. Here we report detailed mechanistic insight into the scission/homologation of CO by two-coordinate iron terphenyl complexes. Mechanistic investigations, conducted using in situ monitoring and reaction sampling techniques (IR, NMR, EPR and Mössbauer spectroscopy) and structural characterisation of isolable species, identify a number of proposed intermediates. Crystallographic and IR spectroscopic data reveal a series of migratory insertion reactions from 1Mes to 4Mes. Further studies past the formation of 4Mes suggest that ketene complexes are formed en route to squaraine 2Mes and iron carboxylate 3Mes, with a number of ketene containing structures being isolated, in addition to the formation of unbound, protonated ketene (8). The synthetic and mechanistic studies are supported by DFT calculations.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Publisher:	Royal Society of Chemistry
ISSN:	2041-6520
Date of First Compliant Deposit:	12 July 2024
Date of Acceptance:	4 May 2024
Last Modified:	25 Oct 2024 13:21
URI:	https://orca.cardiff.ac.uk/id/eprint/170525

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