Guest‐, Light‐ and Thermally‐Modulated Spin Crossover in [FeII2] Supramolecular Helicates |
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| Authors: | Mohanad Darawsheh Dr. Leoni A. Barrios Dr. Olivier Roubeau Dr. Simon J. Teat 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;3. Advanced Light Source, Berkeley Laboratory, Berkeley, California, USA |
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| Abstract: | A new bis(pyrazolylpyridine) ligand (H2L) has been prepared to form functional [Fe2(H2L)3]4+ metallohelicates. Changes to the synthesis yield six derivatives, X@[Fe2(H2L)3]X(PF6)2?xCH3OH ( 1 , x=5.7 and X=Cl; 2 , x=4 and X=Br), X@[Fe2(H2L)3]X(PF6)2?yCH3OH?H2O ( 1 a , y=3 and X=Cl; 2 a , y=1 and X=Br) and X@[Fe2(H2L)3](I3)2?3 Et2O ( 1 b , X=Cl; 2 b , X=Br). Their structure and functional properties are described in detail by single‐crystal X‐ray diffraction experiments at several temperatures. Helicates 1 a and 2 a are obtained from 1 and 2 , respectively, by a single‐crystal‐to‐single‐crystal mechanism. The three possible magnetic states, [LS–LS], [LS–HS], and [HS–HS] can be accessed over large temperature ranges as a result of the structural nonequivalence of the FeII centers. The nature of the guest (Cl? vs. Br?) shifts the spin crossover (SCO) temperature by roughly 40 K. Also, metastable [LS–HS] or [HS–HS] states are generated through irradiation. All helicates (X@[Fe2(H2L)3])3+ persist in solution. |
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| Keywords: | coordination chemistry crystallography iron(II) helicates spin crossover supramolecular chemistry |
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