| Autor: |
Eugenio Coronado, M. Carmen Giménez-López, Saket Asthana, Cédric Desplanches, Jean-François Létard |
| Předmět: |
|
| Zdroj: |
Dalton Transactions: An International Journal of Inorganic Chemistry; Oct2009, Vol. 2009 Issue 38, p8087-8095, 9p |
| Abstrakt: |
This paper is divided into two parts: in the first part, the influence of solvate molecules on the magnetic properties of spin crossover salts of [Fe(bpp)2][Cr(L)(ox)2]ClO4·nS (bpp = 2,6-bis(pyrazol-3yl)pyridine; L = 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen); ox = oxalate dianion; S = solvent) is analyzed. The second part is devoted to the photomagnetic properties of the previously reported [Fe(bpp)2][Cr(L)(ox)2]2family of compounds. The study describes the crystal structure, differential scanning calorimetry (DSC) and magnetic properties of [Fe(bpp)2][Cr(bpy)(ox)2]ClO4·EtOH·4H2O (1) and [Fe(bpp)2][Cr(phen)(ox)2]ClO4·1.5EtOH·4H2O (2). Both salts are high-spin (HS) compounds. Desolvation of 1yields a material exhibiting a gradual spin crossover that involves 50% of the Fe2+cations. Rehydration of this desolvated salt induces a significant increase in the low-spin (LS) population. Desolvation of 2affords a material showing a more abrupt spin crossover with thermal hysteresis (T1/2↑ = 286 K and T1/2↓ = 273 K). This material is not very sensitive to rehydration. The anhydrous compounds [Fe(bpp)2][Cr(bpy)(ox)2]2(3) and [Fe(bpp)2][Cr(phen)(ox)2]2(4) display some quantitative photomagnetic conversion with T(LIESST) values of 41 and 51 K, respectively. Kinetic parameters governing the photo-induced HS–LS relaxation process have been determined and used to reproduce the T(LIESST) curves. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
