EXAFS study on the spin-crossover system, [Fe(4-NH2trz)3](R-SO3)2

Fe K-edge XAFS spectra of one-dimensional chain Fe(II) complexes [Fe(4-NH2trz)3](R-SO3)2 · 2H2O (4-NH2trz=4-amino-1,2,4-triazole, R=CmH2m+1, p-CH3C6H4) were investigated to obtain the local structural information on the spin-crossover phase transition. The distances of the first nearest neighbor Fe-N were almost the same in each sample. The distance of the nearest neighbor Fe-Fe became shorter with increasing the length of alkyl chain of counter-ion.