Effect of the metal dilution on the thermal and light-induced spin transition in [FexMn1−x(bpp)2](NCSe)2: When T(LIESST) reaches T1/2

• Published in: Inorganica Chimica Acta 2008-09, Vol.361 (12-13), p.3529-3533
• Main Authors: Baldé, C., Desplanches, C., Gütlich, P., Freysz, E., Létard, J.F.
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Material chemistry
• ISSN: 0020-1693; 0020-1693
• DOI: 10.1016/j.ica.2008.03.124

The thermal and light-induced spin transition in [FexMn1−x(bpp)2](NCSe)2 (bpp = 2,6-bis(pyrazol-3-yl)pyridine) has been investigated by magnetic susceptibility, photomagnetism and diffuse reflectivity measurements. These complexes display a thermal spin transition and exhibit the light-induced excited spin state trapping (LIESST) effect at low temperature. For each mixed-crystal system, the thermal spin transition temperature, T1/2, and the relaxation temperature of the photo-induced high-spin state, T(LIESST), have been systematically determined. It appears that T1/2 decreases with the metal dilution while T(LIESST) remains unchanged, suggesting that the two interconversion processes are controlled by different factors; i.e. the photomagnetic properties are governed at the molecular scale and the thermal spin crossover regime is affected by both the ligand field and crystal packing effects. For highly metal-diluted complex with x < 0.2, it is found that when T1/2 reaches the T(LIESST), the complex remains HS on the whole range of temperature.