On the Photomagnetic Properties of the Binuclear Spin Crossover Complexes {[Fe(bt)(NCSe)2]2(bpym)} and {[Fe(bpym)(NCSe)2]2(bpym)}

Abstract

Infrared and visible light irradiation effects on the spin state of iron(II) ions have been investigated in the binuclear molecules {[Fe(bt)(NCSe)2]2(bpym)} (4) and {[Fe(bpym)(NCSe)2]2(bpym)} (2). For compound 2 we could observe LIESST and partial reverse-LIESST effects under visible and infrared light irradiation, respectively. Compound 4 exhibits a wavelength-selective photoconversion at 10 K from the low spin (LS–LS) ground state of the binuclear molecule to the metastable high spin (HS–HS) state under visible (785 or 532 nm) light irradiation or to the metastable HS–LS state under infrared (1,342 nm) light irradiation. In addition we also observed the reverse (HS–HS → HS–LS) and the cascade (LS–LS → HS–LS → HS–HS) photoconversions as well. These phenomena lead to complex and original photomagnetic behaviour due to the intramolecular magnetic coupling.