Register      Login
Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
RESEARCH ARTICLE

Cooperative Spin Transitions in Iron(II) Derivatives of 1,2,4-Triazole

KH Sugiyarto and HA Goodwin

Australian Journal of Chemistry 47(2) 263 - 277
Published: 1994

Abstract

Complexes of stoichiometry Fe( trzH )2( trz )X, where trzH is 1,2,4-triazole and X = BF4, ClO4, PF6, have been prepared. All three salts display temperature-induced singlet (1A1) ↔ quintet (5T2) transitions which are generally discontinuous and associated with a broad hysteresis loop. The salts are strongly thermochromic, being white above and pink-lilac below the transition region. Several samples of each salt were obtained and the detailed behaviour varied somewhat from one sample to another. For the fluoroborate and perchlorate salts the transition is centred above room temperature while for the hexafluorophosphate salt it occurs below room temperature. The perchlorate salt was also isolated in a form which showed a continuous transition but the nature of its electronic properties changed as the sample aged. In one form of the hexafluorophosphate salt the hysteresis loop spans room temperature and it has been possible to characterize both the singlet and the quintet state species at that temperature. For all three salts the transition has been characterized by measurement of the temperature dependence of the magnetism and Mossbauer and electronic spectra. These measurements establish that the complexes all contain an FeN6 coordination core and this must be achieved through bridging of the triazole units.

https://doi.org/10.1071/CH9940263

© CSIRO 1994

Committee on Publication Ethics


Export Citation Get Permission

View Dimensions