Abstract
2,6-dipyrazolyl pyridine (bpp) skeleton is a good building unit for iron(II) spin crossover research. Various functional groups can be appended on pyrazolyl and pyridine rings thereby modifying potentially the spin state properties of [Fe(bpp)2]2+ derivatives. In this work, we have worked on substituted pyrazole by grafting an ester function as an electro-attractor group and a methyl substituent as an electro-donating group in 3 and 5 positions, respectively. Mössbauer analyses of the mononuclear complex 1 [FeL2](ClO4)2 (L= diethyl-1,1'-(pyridine-2,6-diyl)bis(5-methyl-1H-pyrazole-3-carboxylate) revealed high-spin iron(II) ions at room temperature. On cooling down to liquid helium temperature, magnetic susceptibility measurements confirmed a paramagnetic state, suggesting that the steric influence of the pyrazole substituents was to great to allow a thermally induced spin crossover to occur.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Wild, A., Winter, A., Schlütter, F., Schubert, U.S.: Advances in the field of π-conjugated 2,2:6,2″-terpyridines. Chem. Soc. Rev. 40, 1459 (2011)
Shunmugam, R., Gabriel, G.J., Aamer, K.A., Tew, G.N.: Metal–Ligand-Containing Polymers: Terpyridine as the Supramolecular Unit. Macromol. Rapid Commun. 31, 784–793 (2010)
Nishihara, H., Kanaizuka, K., Nishimori, Y., Yamanoi, Y.: Construction of redox- and photo-functional molecular systems on electrode surface for application to molecular devices. Coord. Chem. Rev. 251, 2674–2687 (2007)
Boca, M., Jameson, R.F., Linert, W.: Fascinating variability in the chemistry and properties of 2,6-bis-(benzimidazol-2-yl)-pyridine and 2,6-bis-(benzthiazol-2-yl)-pyridine and their complexes. Coord. Chem. Rev. 255, 290–317 (2011)
Halcrow, M.A.: Iron(II) complexes of 2,6-di(pyrazol-1-yl)pyridines—A versatile system for spin-crossover research. Coord. Chem. Rev. 253, 2493–2514 (2009)
Kershaw Cook, L.J., Mohammed, R., Sherborne, G., Roberts, T.D., Alvarez, S., Halcrow, M.A.: Spin state behaviour of iron(II)/dipyrazolylpyridine complexes. New insights from crystallographic and solution measurements. Coord. Chem. Rev. 289–290, 2–12 (2015)
Roberts, T.D., Halcrow, M.A.: Polyhedron. 64, 4–12 (2013)
Olguin, J., Brooker, D.S.: Spin crossover active iron(II) complexes of selected pyrazole pyridine / pyrazine ligands. Coord. Chem. Rev. 255, 203–240 (2011)
Abhervé, A., Recio-Carretero, M.J., López-Jordà, M., Clemente-Juan, J.M., Canet-Ferrer, J., Cantarero, A., Clemente-León, M., Coronado, E.: Nonanuclear spin-crossover complex containing iron(II) and iron(III) based on a 2,6-bis(pyrazol-1-yl)pyridine ligand functionalized with a carboxylate group. Inorg. Chem. 55, 9361–9367 (2016)
Oulmidi, A., Radi S., Idir A., Zyad A., Kabach I., Nhiri M., Robeyns K., Rotaru A., Garcia Y., Synthesis and Cytotoxicity against Tumor Cells of Pincer N-heterocyclic Ligands and their Transition Metal complexes , RSC Adv (2021, submitted).
Lagarec, K., Rancourt, D. G. Recoil, Mössbauer Spectral Analysis software for Windows 1.0; Department of Physics, University of Ottawa Ottawa, ON (1998)
Kulmaczewski, R., Shepherd, H.J., Cespedes, O., Halcrow, M.A.: A Homologous Series of [Fe(H2Bpz2)2(L)] Spin-Crossover Complexes with Annelated Bipyridyl Co-Ligands. Inorg. Chem. 53(18), 9809–9817 (2014)
Halcrow, M.A.: The synthesis and coordination chemistry of 2,6-bis(pyrazolyl)pyridines and related ligands — Versatile terpyridine analogues. Coord. Chem. Rev. 249, 2880 (2005)
Naik, A.D., Garcia, Y.: 57Fe Mössbauer probe of spin crossover thin films on a bio-membrane. Hyperfine Interact. 206, 7–11 (2012)
Naik, A.D., Dîrtu, M.M., Garcia, Y.: Neutral and anionic duality of 1,2,4-triazole α-amino acid scaffold in 1D coordination polymers. Hyperfine Interact. 205, 57–61 (2012)
Roberts, T.D., Little, M.A., Kershaw Cook, L.J., Barrett, S.A., Tuna, F., Halcrow, M.A.: Iron(II) complexes of 2,6-di(1-alkylpyrazol-3-yl)pyridine derivatives – The influence of distal substituents on the spin state of the iron centre. Polyhedron. 64, 4–12 (2013)
Acknowledgements
This research was supported by a bilateral WBI-Morocco grant (COP 22 Program 2018–2022), the Fonds de La Recherche Scientifique—FNRS (CDR 33694457, PDR T.0095.21), PPR2-MESRSFC-CNRST-P10 project (Morocco), CCCDI - UEFISCDI, project number PN-III-CEI-BIM-PBE-2020-0042/8 BM / 2021, Ministère de l’Education et de la Recherche de Roumanie and WBI. We thank CNRST Morocco and WBI-Morocco for an excellence PhD stipendium, UCLouvain international action committee for a PhD scholarship allocated to A.O and GFSM for supporting participation of A.O to ICAME 2021.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
This article is part of the Topical Collection on Proceedings of the International Conference on the Applications of the Mössbauer Effect (ICAME 2021), 5-10 September 2021, Brasov, Romania
Edited by Victor Kuncser
Rights and permissions
About this article
Cite this article
Oulmidi, A., Rotaru, A., Radi, S. et al. Pyrazole's substituents effect on the spin state of [Fe(bpp)2]2+complexes. Hyperfine Interact 242, 8 (2021). https://doi.org/10.1007/s10751-021-01730-w
Accepted:
Published:
DOI: https://doi.org/10.1007/s10751-021-01730-w