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Structural Insights into Hysteretic Spin‐Crossover in a Set of Iron(II)‐2,6‐bis(1 H ‐Pyrazol‐1‐yl)Pyridine) Complexes
Author(s) -
Suryadevara Nithin,
Mizuno Asato,
Spieker Lea,
Salamon Soma,
Sleziona Stephan,
Maas André,
Pollmann Erik,
Heinrich Benoît,
Schleberger Marika,
Wende Heiko,
Kuppusamy Senthil Kumar,
Ruben Mario
Publication year - 2022
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.202103853
Subject(s) - spin crossover , bistability , pyridine , spin transition , crystallography , molecule , chemistry , substituent , molecular switch , thermal hysteresis , spin states , hysteresis , solvent , stereochemistry , materials science , condensed matter physics , inorganic chemistry , physics , medicinal chemistry , phase transition , organic chemistry , optoelectronics
Abstract Bistable spin‐crossover (SCO) complexes that undergo abrupt and hysteretic (Δ T 1/2 ) spin‐state switching are desirable for molecule‐based switching and memory applications. In this study, we report on structural facets governing hysteretic SCO in a set of iron(II)‐2,6‐bis(1 H ‐pyrazol‐1‐yl)pyridine) (bpp) complexes – [Fe(bpp−COOEt) 2 ](X) 2 ⋅ CH 3 NO 2 (X=ClO 4 , 1 ; X=BF 4 , 2 ). Stable spin‐state switching – T 1/2 =288 K; Δ T 1/2 =62 K – is observed for 1 , whereas 2 undergoes above‐room‐temperature lattice‐solvent content‐dependent SCO – T 1/2 =331 K; Δ T 1/2 =43 K. Variable‐temperature single‐crystal X‐ray diffraction studies of the complexes revealed pronounced molecular reorganizations – from the Jahn‐Teller‐distorted HS state to the less distorted LS state – and conformation switching of the ethyl group of the COOEt substituent upon SCO. Consequently, we propose that the large structural reorganizations rendered SCO hysteretic in 1 and 2 . Such insights shedding light on the molecular origin of thermal hysteresis might enable the design of technologically relevant molecule‐based switching and memory elements.