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Spin Crossover in a 3,5‐Bis(2‐pyridyl)‐1,2,4‐triazolate‐Bridged Dinuclear Iron(II) Complex [{Fe(NCBH 3 )(py)} 2 (μ‐L 1 ) 2 ] – Powder versus Single Crystal Study
Author(s) -
Schneider Caspar J.,
Cashion John D.,
Chilton Nicholas F.,
Etrillard Céline,
Fuentealba Mauricio,
Howard Judith A. K.,
Létard JeanFrançois,
Milsmann Carsten,
Moubaraki Boujemaa,
Sparkes Hazel A.,
Batten Stuart R.,
Murray Keith S.
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201201075
Subject(s) - spin crossover , chemistry , spin transition , crystallography , raman spectroscopy , spin states , mössbauer spectroscopy , single crystal , excited state , inorganic chemistry , atomic physics , physics , optics
The structural characteristics and physical properties of the 3,5‐bis(2‐pyridyl)‐1,2,4‐triazolate ( L 1 ) bridged dinuclear iron(II) spin‐crossover complex [{Fe(NCBH 3 )(py)} 2 (μ‐ L 1 ) 2 ] ( 1 ) in both powder ( 1p ) and single crystal ( 1c ) forms have been investigated. Both forms of [{Fe(NCBH 3 )(py)} 2 (μ‐ L 1 ) 2 ] display a thermally induced spin transition; however, the transitions have different T 1/2 values and different degrees of spin conversion. Both forms display the photomagnetic light‐induced excited spin‐state trapping (LIESST) effect as well as reverse LIESST and have been compared by Raman spectral and powder X‐ray diffraction methods, which indicate that they are polymorphs. The single crystal form 1c shows a “half” spin transition and has been further characterised at temperatures above and below the spin transition by low temperature crystallographic methods including single crystal LIESST experiments (at 40 K) and by Mössbauer spectroscopy; thus, the nature of the [HS‐LS] form and the different spin isomers were revealed. To complement the experimental results, compound 1 and several other related Fe II dinuclear spin‐crossover compounds have been evaluated by quantum‐chemical DFT calculations. Additionally, the susceptibilities for the powder form 1p , which displays a complete two‐step spin‐crossover, were also fitted to a phenomenological model for dinuclear spin‐crossover complexes.