Halogen Substitution Effects on N2O Schiff Base Ligands in Unprecedented Abrupt Fe-II Spin Crossover Complexes
Wasinee Phonsri, David S Macedo, Kuduva R Vignesh, Gopalan Rajaraman, Casey G Davies, Guy NL Jameson, Boujemaa Moubaraki, Jas S Ward, Paul E Kruger, Guillaume Chastanet, Keith S Murray
CHEMISTRY-A EUROPEAN JOURNAL | WILEY-V C H VERLAG GMBH | Published : 2017
A family of halogen-substituted Schiff base iron(II) complexes, [FeII (qsal-X)2 ], (qsal-X=5-X-N-(8-quinolyl)salicylaldimines)) in which X=F (1), Cl (2), Br (3) or I (4) has been investigated in detail. Compound 1 shows a temperature invariant high spin state, whereas the others all show abrupt spin transitions, at or above room temperature, namely, 295 K (X=I) up to 342 K (X=Br), these being some of the highest T1/2 values obtained, to date, for FeII N/O species. We have recently reported subtle symmetry breaking in [FeII (qsal-Cl)2 ] 2 with two spin transition steps occurring at 308 and 316 K. A photomagnetic study reveals almost full HS conversion of [FeII (qsal-I)2 ] 4 at low temperature..View full abstract
This work was supported by an Australian Research Council Discovery grant (to K.S.M.). Access to the Australian Synchrotron is gratefully acknowledged. P.E.K. gratefully acknowledges the Royal Society of New Zealand Marsden Fund for financial support. We thank Prof. D. Harding (Walailak University) for valuable discussions, Dr. S.-X. Guo for help with electrochemistry studies and S.S. Volaric (Melbourne University) for EPR assistance.