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Structural and Magnetic Resolution of a Two‐Step Full Spin‐Crossover Transition in a Dinuclear Iron(II) Pyridyl‐Bridged Compound
Author(s) -
Amoore Jarrod J. M.,
Kepert Cameron J.,
Cashion John D.,
Moubaraki Boujemaa,
Neville Suzanne M.,
Murray Keith S.
Publication year - 2006
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.200601069
Subject(s) - spin crossover , spin transition , crystallography , chemistry , molecule , spin states , transition metal , pyridine , ligand (biochemistry) , mössbauer spectroscopy , crystal structure , inorganic chemistry , organic chemistry , catalysis , biochemistry , receptor
A dinuclear iron(II) complex containing the new pyridyl bridging ligand, 2,5‐di(2′,2′′‐dipyridylamino)pyridine (ddpp) has been synthesised and characterised by single‐crystal X‐ray diffraction, magnetic susceptibility and Mössbauer spectral methods. This compound, [Fe 2 (ddpp) 2 (NCS) 4 ] ⋅ 4 CH 2 Cl 2 , undergoes a two‐step full spin crossover. Structural analysis at each of the three plateau temperatures has revealed a dinuclear molecule with spin states HS–HS, HS–LS and LS–LS (HS: high spin, LS: low spin) for the two iron(II) centres. This is the first time that resolution of the metal centres in a HS–LS ordered state has been achieved in a two‐step dinuclear iron(II) spin‐crossover compound. Thermogravimetric data show that the dichloromethane solvate molecules can be removed in two distinct steps at 120 °C and 200 °C. The partially de‐solvated clathrate, [Fe 2 (ddpp) 2 (NCS) 4 ] ⋅ CH 2 Cl 2 , undergoes a one‐step transition with an increased transition temperature with respect to the as synthesised material. Structural characterisation of this material reveals subtle changes to the coordination geometries at each of the iron(II) centres and striking changes to the local environment of the dinuclear complex. The fully de‐solvated material remains high spin over all temperatures. Interestingly, the solvent can be re‐introduced into the monosolvated solid to achieve complete conversion back to the original two‐step crossover material, [Fe 2 (ddpp) 2 (NCS) 4 ] ⋅ 4 CH 2 Cl 2 .