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Thermal‐ and Light‐Induced Spin Crossover in a Guest‐Dependent Dinuclear Iron(II) System
Author(s) -
Amoore Jarrod J. M.,
Neville Suzanne M.,
Moubaraki Boujemaa,
Iremonger Simon S.,
Murray Keith S.,
Létard JeanFrançois,
Kepert Cameron J.
Publication year - 2010
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.200901809
Subject(s) - spin crossover , monoclinic crystal system , chemistry , dichloromethane , chloroform , crystallography , pyridine , molecule , spin transition , crystal structure , crystal (programming language) , stereochemistry , medicinal chemistry , solvent , organic chemistry , computer science , programming language
We previously reported the dinuclear material [Fe II 2 (ddpp) 2 (NCS) 4 ] ⋅ 4 CH 2 Cl 2 ( 1⋅ 4 CH 2 Cl 2 ; ddpp=2,5‐di(2′,2′′‐dipyridylamino)pyridine) and its partially desolvated analogue ( 1⋅ CH 2 Cl 2 ), which undergo two‐ and one‐step spin‐crossover (SCO) transitions, respectively. Here, we manipulate the type and degree of solvation in this system and find that either a one‐ or two‐step spin transition can be specifically targeted. The chloroform clathrate 1⋅ 4 CHCl 3 undergoes a relatively abrupt one‐step SCO, in which the two equivalent Fe II sites within the dinuclear molecule crossover simultaneously. Partial desolvation of 1⋅ 4 CHCl 3 to form 1⋅ 3 CHCl 3 and 1⋅ CHCl 3 occurs through single‐crystal‐to‐single‐crystal processes (monoclinic C 2/ c to P 2 1 / n to P 2 1 / n ) in which the two equivalent Fe II sites become inequivalent sites within the dinuclear molecule of each phase. Both 1⋅ 3 CHCl 3 and 1⋅ CHCl 3 undergo one‐step spin transitions, with the former having a significantly higher SCO temperature than 1⋅ 4 CHCl 3 and the latter, and each has a broader SCO transition than 1⋅ 4 CHCl 3 , attributable to the overlap of two SCO steps in each case. Further magnetic manipulation can be carried out on these materials through reversibly resolvating the partially desolvated material with chloroform to produce the original one‐step SCO, or with dichloromethane to produce a two‐step SCO reminiscent of that seen for 1⋅ 4 CH 2 Cl 2 . Furthermore, we investigate the light‐induced excited spin state trapping (LIESST) effect on 1⋅ 4 CH 2 Cl 2 and 1⋅ CH 2 Cl 2 and observe partial LIESST activity for the former and no activity for the latter.