The University of Southampton
University of Southampton Institutional Repository
Warning ePrints Soton is experiencing an issue with some file downloads not being available. We are working hard to fix this. Please bear with us.

Electronic structure of cobalt-corrole-pyridine complexes: noninnocent five-coordinate Co(II) corrole-radical states

Electronic structure of cobalt-corrole-pyridine complexes: noninnocent five-coordinate Co(II) corrole-radical states
Electronic structure of cobalt-corrole-pyridine complexes: noninnocent five-coordinate Co(II) corrole-radical states

Two sets of complexes of Co-triarylcorrole-bispyridine complexes, Co[TpXPC](py)2 and Co[Br8TpXPC](py)2 have been synthesized, where TpXPC refers to a meso-tris(para-X-phenyl)corrole ligand with X = CF3, H, Me, and OMe and Br8TpXPC to the corresponding β-octabrominated ligand. The axial pyridines in these complexes were found to be labile and, in dilute solutions in dichloromethane, the complexes dissociate almost completely to the five-coordinate monopyridine complexes. Upon addition of a small quantity of pyridine, the complexes revert back to the six-coordinate forms. These transformations are accompanied by dramatic changes in color and optical spectra. 1H NMR spectroscopy and X-ray crystallography have confirmed that the bispyridine complexes are authentic low-spin Co(III) species. Strong substituent effects on the Soret maxima and broken-symmetry DFT calculations, however, indicate a CoII-corrole2- formulation for the five-coordinate Co[TpXPC](py) series. The calculations implicate a Co(dz2)-corrole("a2u") orbital interaction as responsible for the metal-ligand antiferromagnetic coupling that leads to the open-shell singlet ground state of these species. Furthermore, the calculations predict two low-energy S = 1 intermediate-spin Co(III) states, a scenario that we have been able to experimentally corroborate with temperature-dependent EPR studies. Our findings add to the growing body of evidence for noninnocent electronic structures among first-row transition metal corrole derivatives.

1089-5639
9589-9598
Ganguly, Sumit
0e87078e-c576-4b20-a10d-dafd6288f8b2
Conradie, Jeanet
814b9b0c-ae44-4f35-b80b-4d27bd575030
Bendix, Jesper
3be042eb-7569-4efb-b02d-54923499f4e8
Gagnon, Kevin J.
5535af49-cc12-48b8-b007-28bb1f1b070c
McCormick, Laura J.
f1c2f8cd-adcc-4bbf-9289-0b33a006d2bb
Ghosh, Abhik
01a311da-a139-43f0-ae29-0efa0e8788f7
Ganguly, Sumit
0e87078e-c576-4b20-a10d-dafd6288f8b2
Conradie, Jeanet
814b9b0c-ae44-4f35-b80b-4d27bd575030
Bendix, Jesper
3be042eb-7569-4efb-b02d-54923499f4e8
Gagnon, Kevin J.
5535af49-cc12-48b8-b007-28bb1f1b070c
McCormick, Laura J.
f1c2f8cd-adcc-4bbf-9289-0b33a006d2bb
Ghosh, Abhik
01a311da-a139-43f0-ae29-0efa0e8788f7

Ganguly, Sumit, Conradie, Jeanet, Bendix, Jesper, Gagnon, Kevin J., McCormick, Laura J. and Ghosh, Abhik (2017) Electronic structure of cobalt-corrole-pyridine complexes: noninnocent five-coordinate Co(II) corrole-radical states. Journal of Physical Chemistry A, 121 (50), 9589-9598. (doi:10.1021/acs.jpca.7b09440).

Record type: Article

Abstract

Two sets of complexes of Co-triarylcorrole-bispyridine complexes, Co[TpXPC](py)2 and Co[Br8TpXPC](py)2 have been synthesized, where TpXPC refers to a meso-tris(para-X-phenyl)corrole ligand with X = CF3, H, Me, and OMe and Br8TpXPC to the corresponding β-octabrominated ligand. The axial pyridines in these complexes were found to be labile and, in dilute solutions in dichloromethane, the complexes dissociate almost completely to the five-coordinate monopyridine complexes. Upon addition of a small quantity of pyridine, the complexes revert back to the six-coordinate forms. These transformations are accompanied by dramatic changes in color and optical spectra. 1H NMR spectroscopy and X-ray crystallography have confirmed that the bispyridine complexes are authentic low-spin Co(III) species. Strong substituent effects on the Soret maxima and broken-symmetry DFT calculations, however, indicate a CoII-corrole2- formulation for the five-coordinate Co[TpXPC](py) series. The calculations implicate a Co(dz2)-corrole("a2u") orbital interaction as responsible for the metal-ligand antiferromagnetic coupling that leads to the open-shell singlet ground state of these species. Furthermore, the calculations predict two low-energy S = 1 intermediate-spin Co(III) states, a scenario that we have been able to experimentally corroborate with temperature-dependent EPR studies. Our findings add to the growing body of evidence for noninnocent electronic structures among first-row transition metal corrole derivatives.

This record has no associated files available for download.

More information

e-pub ahead of print date: 11 December 2017
Published date: 21 December 2017

Identifiers

Local EPrints ID: 439006
URI: http://eprints.soton.ac.uk/id/eprint/439006
ISSN: 1089-5639
PURE UUID: 981ec0c7-5f05-43b0-93a4-032ac28d8ec2
ORCID for Laura J. McCormick: ORCID iD orcid.org/0000-0002-6634-4717

Catalogue record

Date deposited: 31 Mar 2020 16:31
Last modified: 16 Sep 2021 11:14

Export record

Altmetrics

Contributors

Author: Sumit Ganguly
Author: Jeanet Conradie
Author: Jesper Bendix
Author: Kevin J. Gagnon
Author: Abhik Ghosh

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×