10.1021/ic403035u.s002
Irene Bräunlich
Irene
Bräunlich
Antoni Sánchez-Ferrer
Antoni
Sánchez-Ferrer
Matthias Bauer
Matthias
Bauer
Rahel Schepper
Rahel
Schepper
Philippe Knüsel
Philippe
Knüsel
Julia Dshemuchadse
Julia
Dshemuchadse
Raffaele Mezzenga
Raffaele
Mezzenga
Walter Caseri
Walter
Caseri
Polynuclear Iron(II)–Aminotriazole Spincrossover
Complexes (Polymers) In Solution
American Chemical Society
2014
EXAFS
molar NH 2trz ratio
DMF
SCO
SAXS
NH 2trz
polynuclear species
UV
Fe
equilibrium
XANES
2014-04-07 00:00:00
Dataset
https://acs.figshare.com/articles/dataset/Polynuclear_Iron_II_Aminotriazole_Spincrossover_Complexes_Polymers_In_Solution/2308357
Polynuclear spincrossover (SCO) complexes
prepared by the combination of [Fe(DMF)<sub>6</sub>]<sup>2+</sup> and
NH<sub>2</sub>trz (NH<sub>2</sub>trz = 4-amino-1,2,4-triazole) were
studied (2ns<sup>–</sup> = counterion 2-naphthalenesulfonate).
It is demonstrated that these [Fe(NH<sub>2</sub>trz)<sub>3</sub>](2ns)<sub>2</sub> complexes can be dissolvedcontrary to common reported
experiencein <i>N</i>,<i>N</i>-dimethylformamide
(DMF) and, therefore, can be conveniently processed by simple means.
The resulting solutions were examined with UV/vis and X-ray absorption
spectroscopy (XANES and EXAFS) as well as with small-angle X-ray scattering
(SAXS). At a molar NH<sub>2</sub>trz/Fe<sup>2+</sup> ratio of 3/1,
corresponding to the stoichiometric ratio of the ideal coordination
compound, [Fe(NH<sub>2</sub>trz)<sub>3</sub>]<sup>2+</sup> in the
low-spin state was found to be in equilibrium with polynuclear species
in the high-spin state. The equilibrium can be shifted virtually completely
to the side of low-spin Fe<sup>2+</sup> by an excess of the ligand.
The polymer therewith formed contains 100 or more Fe<sup>2+</sup> ions
and is of a pronounced rigid-rod structure, with Fe–Fe distances
around 3.32 Å (in comparison to 3.94 Å of the polynuclear
species in the high-spin state). Reversible spin crossover takes place
in solution upon a temperature increase to around 60 °C; this
process is associated with a shift in equilibrium toward species shorter
than the initial polynuclear species.