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Rapid Cooling Experiments and Use of an Anionic Nuclear Probe to Sense the Spin Transition of the 1D Coordination Polymers [Fe(NH 2 trz) 3 ]SnF 6 ⋅ n H 2 O (NH 2 trz=4‐amino‐1,2,4‐triazole)
Author(s) -
Garcia Yann,
Ksenofontov Vadim,
Mentior Sophie,
Dîrtu Marinela M.,
Gieck Christine,
Bhatthacharjee Ashis,
Gütlich Philipp
Publication year - 2008
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.200701305
Subject(s) - spin crossover , thermal hysteresis , spin transition , ion , hysteresis , mössbauer spectroscopy , spin (aerodynamics) , crystallography , chemistry , jahn–teller effect , materials science , condensed matter physics , phase transition , physics , thermodynamics , organic chemistry
[Fe(NH 2 trz) 3 ]SnF 6 ⋅ n H 2 O (NH 2 trz=4‐amino‐1,2,4‐triazole; n =1 ( 1 ), n =0.5 ( 2 )) are new 1D spin‐crossover coordination polymers. Compound 2 exhibits an incomplete spin transition centred at around 210 K with a thermal hysteresis loop approximately 16 K wide. The spin transition of 2 was detected by the Mössbauer resonance of the 119 Sn atom in the SnF 6 2− anion primarily on the basis of the evolution of its local distortion. Rapid‐cooling 57 Fe Mössbauer and superconducting quantum interference device experiments allow dramatic widening of the hysteresis width of 2 from 16 K up to 82 K and also shift the spin‐transition curve into the room temperature region. This unusual behaviour of quenched samples on warming is attributed to activation of the molecular motion of the anions from a frozen distorted form towards a regular form at temperatures well above approximately 210 K. Potential applications of this new family of materials are discussed.