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Structural Diversity in Cyclometalated Diiridium(III) Complexes with Bridging syn and anti μ2‐Oxamidato and μ2‐Dithioxamidato Ligands

M'hamedi, Ahmed; Batsanov, Andrei S.; Fox, Mark A.; Aguilar, Juan A.; Bryce, Martin R.

Structural Diversity in Cyclometalated Diiridium(III) Complexes with Bridging syn and anti μ2‐Oxamidato and μ2‐Dithioxamidato Ligands Thumbnail


Authors

Ahmed M'hamedi

Andrei S. Batsanov



Abstract

Six new diiridium complexes containing 2-methyl-6-phenylpyridyl as the cyclometalating ligand with a μ2-oxamidato or a μ2-dithioxamidato ligand as the bridge have been synthesized in 60–73 % yields. These complexes were revealed by multinuclear NMR spectroscopy to contain inseparable mixtures of diastereomers (rac, ΔΔ/ΛΛ and meso, ΔΛ) with bridges in anti and syn configurations. The remarkable variety of isomers present was confirmed by X-ray crystallography on single crystals grown from mixtures of each complex. In one complex with a N,N’-bis(4-trifluoromethylphenyl)-μ2-oxamidato bridge, two single crystals of anti and syn isomers were structurally determined. Two single crystals of the μ2-dithioxamidato bridge complex were found to contain rac and meso forms of the syn isomer. Hybrid DFT computations on the four isomers of each diiridium complex revealed negligible energetic preferences for one isomer despite the methyl groups in the 2-methyl-6-phenylpyridyl cyclometalating ligands being close to the neighboring methyl groups and the bridge, thus supporting the experimental findings of isomer mixtures. Two distinct broad emissions with maxima at 522–529 nm and at 689–701 nm observed in these complexes in dichloromethane are attributed to mixed metal-ligand to ligand charge transfer (MLLCT) excited states involving the pyridyl and bridge moieties respectively with the aid of electronic structure computations.

Citation

M'hamedi, A., Batsanov, A. S., Fox, M. A., Aguilar, J. A., & Bryce, M. R. (2023). Structural Diversity in Cyclometalated Diiridium(III) Complexes with Bridging syn and anti μ2‐Oxamidato and μ2‐Dithioxamidato Ligands. European Journal of Inorganic Chemistry, https://doi.org/10.1002/ejic.202300423

Journal Article Type Article
Acceptance Date Sep 15, 2023
Online Publication Date Oct 4, 2023
Publication Date 2023
Deposit Date Nov 1, 2023
Publicly Available Date Nov 1, 2023
Journal European Journal of Inorganic Chemistry
Print ISSN 1434-1948
Electronic ISSN 1099-0682
Publisher Wiley-VCH Verlag
Peer Reviewed Peer Reviewed
DOI https://doi.org/10.1002/ejic.202300423
Keywords Inorganic Chemistry
Public URL https://durham-repository.worktribe.com/output/1874020

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Copyright Statement
© 2023 The Authors. European Journal of Inorganic Chemistry published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.




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