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An Incomplete Spin Transition Associated with a Z ′=1→ Z ′=24 Crystallographic Symmetry Breaking
Author(s) -
Capel Berdiell Izar,
Kulmaczewski Rafal,
Cespedes Oscar,
Halcrow Malcolm A.
Publication year - 2018
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.201704896
Subject(s) - crystallography , spin crossover , phase transition , spin transition , intermolecular force , perchlorate , phase (matter) , chemistry , crystal structure , crystal (programming language) , acetamide , spin (aerodynamics) , molecule , stereochemistry , condensed matter physics , physics , thermodynamics , ion , organic chemistry , computer science , programming language
Crystalline [Fe L 2 ][BF 4 ] 2 ⋅ Me 2 CO ( L=N ‐[2,6‐di{pyrazol‐1‐yl}pyrid‐4‐yl]acetamide) is high‐spin at room temperature, and undergoes an abrupt, hysteretic spin‐crossover at T1 / 2 =137 K (Δ T1 / 2 =14 K) that proceeds to about 50 % completeness. This is associated with a crystallographic phase transition, from phase 1 ( P 2 1 / c , Z= 4) to phase 2 ( P 2 1 , Z= 48). The cations associate into chains in the crystal through weak intermolecular π⋅⋅⋅π interactions. Phase 2 contains a mixture of high‐spin and low‐spin molecules, which are grouped into triads along these chains. The perchlorate salt [Fe L 2 ][ClO 4 ] 2 ⋅ Me 2 CO also adopts phase 1 at room temperature but undergoes a different phase transition near 135 K to phase 3 ( P 2 1 / c , Z= 8) without a change in spin state.