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A Sequential Method to Prepare Polymorphs and Solvatomorphs of [Fe(1,3‐bpp) 2 ](ClO 4 ) 2 ⋅ n H 2 O ( n =0, 1, 2) with Varying Spin‐Crossover Behaviour
Author(s) -
BartualMurgui Carlos,
Codina Carlota,
Roubeau Olivier,
Aromí Guillem
Publication year - 2016
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.201601843
Subject(s) - crystallography , hydrate , powder diffraction , single crystal , spin crossover , chemistry , molecule , x ray crystallography , crystal structure , pyridine , diffraction , materials science , organic chemistry , physics , optics
Two polymorphs of the spin crossover (SCO) compound [Fe(1,3‐bpp) 2 ](ClO 4 ) 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 H 2 O molecules from the solvatomorph [Fe(1,3‐bpp) 2 ](ClO 4 ) 2 ⋅2 H 2 O ( 2 ⋅2 H 2 O), using single‐crystal‐to‐single‐crystal (SCSC) transformations. Hydrate 2 ⋅2 H 2 O is obtained through the same reaction as 1 , now with 2.5 % of water added. Compounds 2 and 2 ⋅2 H 2 O 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 ](ClO 4 ) 2 ⋅H 2 O ( 2 ⋅H 2 O), 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 T 1/2↑ =279/316 K and T 1/2↓ =276/314 K (near 40 K of shift) and different cooperativity.