Sb. Erenburg et al., Thermally and optically induced spin transition effect on the structure ofiron(II) polymeric complexes, J SYNCHROTR, 6, 1999, pp. 576-578
Polymeric iron(II) complexes of the composition Fe(atrz)(3)A(2), where atrz
= 4-amino-1,2,4-triazole, A = anions, have been synthesized and characteri
zed. The compounds exhibit an abrupt thermally driven spin transition (S=0
- S=2) at temperatures varying from 175 K to 400 K depend on composition. X
AFS measurements were performed at the VEPP-3 storage ring at the Budker In
stitute of Nuclear Physics in Novosibirsk. In all studied compounds the Fe-
N and Fe-C interatomic distances increase upon the thermally induced transi
tion to the high spin (HS) state by amounts from 0.12 Angstrom to 0.24 Angs
trom. The existence of long-life optically excited metastable HS states was
established for the Fe(atrz)(3)(ClO4)(2) at 4.2 K. The changes in structur
e upon the transition to a metastable HS state differ from those in the the
rmally induced spin transition.