Kh. Sugiyarto et al., STRUCTURAL, MAGNETIC AND MOSSBAUER STUDIES OF BIS(2,6-BIS(PYRAZOL-3-YL)PYRIDINE)IRON(II) TRIFLATE AND ITS HYDRATES, Australian Journal of Chemistry, 50(9), 1997, pp. 869-873
The electronic properties of bis(2,6-bis(pyrazol-3-yl)pyridine)iron(I
triflate depend markedly on the extent of hydration. The trihydrate is
low spin while the monohydrate is high spin at room temperature but u
ndergoes a discontinuous transition to low spin at low temperatures. I
n the anhydrous complex magnetic and Mossbauer spectral data indicate
that there is a minor fraction of low-spin species at room temperature
and this fraction increases at low temperatures. The spin transition
in the anhydrous salt is continuous and incomplete at 80 K. The struct
ure of the trihydrate reveals an extensive hydrogen-bonding network wh
ich involves the uncoordinated >NH groups of the pyrazolyl groups in t
he ligands, the water molecules and the anions. The disruption of this
network on loss of water is believed to be responsible for the change
in electronic properties. Bis(2,6-bis(pyrazol-3-yl)pyridine)iron(II)
triflate trihydrate: triclinic, space group P (1) over bar, a 11.490(5
), b 12.218(6), c 13.666(6) Angstrom, alpha 104.67(2), beta 104.58(2),
gamma 104.35(2)degrees, Z 2.