EFFECT OF POWDER DISPERSION ON THE (1)A(1)REVERSIBLE-ARROW-T-5(2) SPIN TRANSITION IN FE(II) COMPLEXES WITH 4-AMINO-1,2,4-TRIAZOLE

A series of Fe(II) complexes with 4-amino-1,2,4-triazole ground in an agate mortar for 10 min is studied by Mossbauer spectroscopy. Strong e ffects of powder dispersion both on the (1)A(1) reversible arrow T-5(2 ) spin transition and on the structure dynamic characteristics of the complexes are found. Thus at 295 K the high-spin form of Fe(II) appear s in the samples or its fraction increases; the ionicity of Fe-N bonds and the extent of distortion of the octahedral environment of iron at oms for the low-spin phases of the complexes also increase. It is esta blished that powder dispersion markedly affects the probability of the Mossbauer effect and the vibrational spectrum of the lattice of coord ination compounds. For both the low- and high-spirt phases of the comp lexes, it is reported that the vibrational spectrum is ''softened.'' T he main reason for these effects is supposed to be defectiveness rathe r than the size of the particles due to mechanical activation of the p owder.