Iron(II) spin transition 1,2,4-triazole chain compounds with novel inorganic fluorinated counteranions

New one-dimensional spin transition coordination polymers of formula [Fe(NH2trz)3](AF6) · nH2O (A = Ti, Zr, Sn; NH2trz = 4-amino-1,2,4-triazole) have been synthesized in MeOH and EtOH media. These materials display an abrupt and hysteretic spin transition around 200 K as well as a reversible thermochromic effect on cooling. A preliminary evaluation of the lattice dynamics in the high-spin and low-spin states is presented.

χMT versus T on cooling and warming modes for [Fe(NH2trz)3]TiF6 · nH2O (n = 0.5 (
• ); n = 1 (∘)) and [Fe(NH2trz)3]SnF6 · 0.5H2O (■).Figure optionsDownload as PowerPoint slide