An unprecedented square planar Fe(III) complex exhibiting spin crossover between the spin-admixed states

The presence of strong spin-orbit coupling, which is comparable to the crystal field in certain ferric-porphyrin/phthalocyanine derivatives, results in a spin-admixed state between the high-spin (HS; S = 5/2) and intermediate-spin (IS; S = 3/2) states. However, there are no literature precedents for...

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Hauptverfasser: Ansari, Kamal (Verfasst von) , Borah, Dipanti (Verfasst von) , Spillecke, Lena (Verfasst von) , Thangavel, Kavipriya (Verfasst von) , Kumar, Pardeep (Verfasst von) , Dua, Purva (Verfasst von) , Dey, Sourav (Verfasst von) , Klingeler, Rüdiger (Verfasst von) , Clémancey, Martin (Verfasst von) , Rasamsetty, Amaleswari (Verfasst von) , Hill, Stephen (Verfasst von) , Blondin, Geneviève (Verfasst von) , Rajaraman, Gopalan (Verfasst von) , Shanmugam, Maheswaran (Verfasst von)
Dokumenttyp: Article (Journal)
Sprache:Englisch
Veröffentlicht: 2026
In: Chemistry - a European journal
Year: 2026, Pages: 1-9
ISSN:1521-3765
DOI:10.1002/chem.70994
Online-Zugang:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1002/chem.70994
Verlag, lizenzpflichtig, Volltext: https://onlinelibrary.wiley.com/doi/abs/10.1002/chem.70994
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Verfasserangaben:Kamal Uddin Ansari, Dipanti Borah, Lena Spillecke, Kavipriya Thangavel, Pardeep Kumar, Purva Dua, Sourav Dey, Rüdiger Klingeler, Martin Clémancey, Amaleswari Rasamsetty, Stephen Hill, Geneviève Blondin, Gopalan Rajaraman, Maheswaran Shanmugam
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Zusammenfassung:The presence of strong spin-orbit coupling, which is comparable to the crystal field in certain ferric-porphyrin/phthalocyanine derivatives, results in a spin-admixed state between the high-spin (HS; S = 5/2) and intermediate-spin (IS; S = 3/2) states. However, there are no literature precedents for spin admixing between the IS (S = 3/2) and low-spin (LS; S = 1/2) states, which are purely governed by axial ligation. It is also true that systems showing spin-admixed behavior do not exhibit thermal equilibrium between the spin states, that is, spin crossover (SCO). In this article, we report a unique and rare square planar ferric ion complex, [Na(DME)3][Fe(L12−)2] (1), which exhibits two different physical phenomena: SCO is observed between the spin-admixed states, a phenomenon unprecedented in this context. Field- and temperature-dependent Mössbauer spectra, variable temperature X-band EPR spectra, multifrequency EPR (MF-EPR), and temperature-dependent magnetic susceptibility measurements reveal that the spin-admixed state has contributions from IS (S = 3/2) and LS (S = 1/2), unlike other reports in the literature. The detailed electronic structure of 1, along with the rationale for quantum spin admixing and SCO, is well supported by theoretical calculations.
Beschreibung:Gesehen am 12.06.2026
Beschreibung:Online Resource
ISSN:1521-3765
DOI:10.1002/chem.70994