[Zurück]

M. Tafili-Kryeziu, M. Weil, T. Muranaka, A. Bousseksou, M. Hasegawa, A. Jun, W. Linert:
"Effect of the Counter-anion on the Spin-Transition Properties of a Family of Fe(II) tetrazole complexes, [Fe(i4tz)6]X2 (X = ClO4-, PF6-, SbF6-, BF4-)";
Dalton Transactions, 42 (2013), 44; S. 15796 - 15804.

The monodentate ligand 1-isobutyl-1H-tetrazole (i4tz) was used to synthesize a series of iron(II) spin-crossover (SCO) complexes with general formula [Fe(i4tz)6]X2, where X= ClO4ˉ (1) , PF6ˉ (2), SbF6ˉ (3), BF4ˉ(4). Upon cooling, magnetic susceptibility measurements of compounds 1, 2 and 3 show a reversible one-step spin crossover (SCO) behaviour between HS (S = 2) and LS (S = 0) states without hysteresis. The ClO4ˉ compound shows a gradual spin transition at T1/2 = 208 K at considerably higher temperature than the other compounds. The larger anions PF6ˉ (T1/2 = 114 K) and SbF6ˉ (T1/2 = 116 K) show more gradual transitions, and a "frozen-in effect" was observed after fast cooling. The crystal structure of [Fe(i4tz)6](SbF6)2 (3) was determined at 296, 200 and 100 K, revealing a reversible first-order phase transition between 200 and 100 K, accompanied with a triplication of the unit cell volume at 100 K. Temperature-dependent vibration and electronic spectroscopic measurements of compound 1 were compared with the magnetic susceptibility measurements.

spin-crossover, iron(III) complexes, Tetrazoles

http://dx.doi.org/10.1039/C3DT52339J