Galadzhun, I orcid.org/0000-0002-0512-3830, Kulmaczewski, R orcid.org/0000-0002-3855-4530, Cespedes, O orcid.org/0000-0002-5249-9523 et al. (4 more authors) (2018) 2,6-Di(pyrazol-1-yl)pyridine-4-carboxylate Esters with Alkyl Chain Substituents, and their Iron(II) Complexes. Inorganic Chemistry, 57 (21). pp. 13047-14012. ISSN 0020-1669
Abstract
Two series of 4-(alkoxyphenyl) 2,6-bis{pyrazol-1-yl}pyridine-4-carboxyate (L3R) or alkyl 2,6-bis{pyrazol-1-yl}pyridine-4-carboxyate (L4R) esters have been synthesized and complexed to iron(II), where R = CnH2n+1 (n = 6, 12, 14, 16, 18); two other derivatives related to L3R are also reported. While the solid [Fe(L4R)2][BF4]2 compounds are isostructural by powder diffraction and show similar spin state behaviors, the [Fe(L3R)2][BF4]2 series shows more varied structures and magnetic properties. This was confirmed by solvated crystal structures of [Fe(L3R)2][BF4]2 with n = 6, 14, 16, which all adopt the P1̅ space group but show significantly different side-chain conformations and/or crystal packing. The solid complexes are mostly low spin at room temperature, with many exhibiting the onset of thermal spin crossover (SCO) upon warming. Heating the complexes with n ≥ 14 significantly above their SCO temperature transforms them irreversibly into a predominantly high spin state, which is accompanied by structure changes and loss of crystallinity by powder diffraction. These transformations do not coincide with lattice solvent loss and may reflect melting and refreezing of their alkyl chain conformations during the thermal cycle. Four of the complexes exhibit SCO in CD3CN solution with T1/2 = 273–277 K, which is apparently unaffected by their alkyl chain substituents.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.inorgchem.8b02289. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemistry (Leeds) > Inorganic Chemistry (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Condensed Matter (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) |
Funding Information: | Funder Grant number EPSRC EP/K012568/1 EPSRC EP/K00512X/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 16 Oct 2018 10:35 |
Last Modified: | 19 Dec 2024 09:07 |
Status: | Published |
Publisher: | American Chemical Society |
Identification Number: | 10.1021/acs.inorgchem.8b02289 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:137202 |