A Sequential Method to Prepare Polymorphs and Solvatomorphs of [Fe(1,3‐bpp)2](ClO4)2⋅nH2O (n=0, 1, 2) with Varying Spin‐Crossover Behaviour |
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| Authors: | Dr. Carlos Bartual‐Murgui Carlota Codina Dr. Olivier Roubeau Dr. Guillem Aromí |
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| Affiliation: | 1. Departement de Inorgánica, Universitat de Barcelona, Barcelona, Spain;2. Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC and, Universidad de Zaragoza, Zaragoza, Spain |
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| Abstract: | Two polymorphs of the spin crossover (SCO) compound [Fe(1,3‐bpp)2](ClO4)2 ( 1 and 2 ; 1,3‐bpp=2‐(pyrazol‐1‐yl)‐6‐(pyrazol‐3‐yl)pyridine) were prepared using a novel, stepwise procedure. Crystals of 1 deposit from dry solvents, while 2 is obtained from a solid‐state procedure, by sequentially removing lattice H2O molecules from the solvatomorph [Fe(1,3‐bpp)2](ClO4)2?2 H2O ( 2 ?2 H2O), using single‐crystal‐to‐single‐crystal (SCSC) transformations. Hydrate 2 ?2 H2O is obtained through the same reaction as 1 , now with 2.5 % of water added. Compounds 2 and 2 ?2 H2O are unstable in the atmosphere and absorb or lose one equivalent of water, respectively, to both yield the stable solvatomorph [Fe(1,3‐bpp)2](ClO4)2?H2O ( 2 ?H2O), also following SCSC processes. The four derivatives have been characterised by single‐crystal X‐ray diffraction (SCXRD). Furthermore, the homogeneity of the various compounds as well as their SCSC interconversions have been confirmed by powder X‐ray diffraction (PXRD). Polymorphs 1 and 2 exhibit abrupt SCO behaviour near room temperature with T1/2↑=279/316 K and T1/2↓=276/314 K (near 40 K of shift) and different cooperativity. |
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| Keywords: | iron polymorphism single-crystal-to-single-crystal solvatomorphs spin crossover |
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