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Unusual Magneto‐Structural Features of the Halo‐Substituted Materials [Fe III (5‐X‐salMeen) 2 ]Y: a Cooperative [HS‐HS]↔[HS‐LS] Spin Transition
Author(s) -
AlAzzani Mariam A.,
AlMjeni Faizah,
Mitsuhashi Ryoji,
Mikuriya Masahiro,
AlOmari Imaddin A.,
Robertson Craig C.,
Bill Eckhard,
Shongwe Musa S.
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904744
Subject(s) - crystallography , chemistry , perchlorate , spin crossover , crystal structure , spin transition , halogen , transition metal , ion , alkyl , biochemistry , organic chemistry , catalysis
X‐ray structures of the halo‐substituted complexes [Fe III (5‐X‐salMeen) 2 ]ClO 4 (X=F, Cl, Br, I) [salMeen= N ‐methyl‐ N ‐(2‐aminoethyl)salicylaldiminate]at RT have revealed the presence of two discrete HS complex cations in the crystallographic asymmetric unit with two perchlorate counter ions linking them by N−H amine ⋅⋅⋅O perchlorate interactions. At 90 K, the two complex cations are distinctly HS and LS, a rare crystallographic observation of this coexistence in the Fe III ‐salRen (R=alkyl) spin‐crossover (SCO) system. At both temperatures, crystal packing shows dimerization through C−H imine ⋅⋅⋅O phenolate interactions, a key feature for SCO cooperativity. Moreover, there are noncovalent contacts between the complex cations through type‐II halogen‐halogen bonds, which are novel in this system. The magnetic profiles and Mössbauer spectra concur with the structural analyses and reveal 50 % SCO of the type [HS‐HS]↔[HS‐LS] with a broad plateau. In contrast, [Fe III (5‐Cl‐salMeen) 2 ]BPh 4 ⋅2MeOH is LS and exhibits a temperature‐dependent crystallographic phase transition, exemplifying the influence of lattice solvents and counter ions on SCO.