Synthesis and Characterization of a New Family of Bi-, Tri-, Tetra-, and
Pentanuclear Ferric Complexes
Colette Boskovic
Andreas Sieber
Grégory Chaboussant
Hans U. Güdel
Jürgen Ensling
Wolfgang Wernsdorfer
Antonia Neels
Gael Labat
Helen Stoeckli-Evans
Stefan Janssen
10.1021/ic049600f.s001
https://acs.figshare.com/articles/dataset/Synthesis_and_Characterization_of_a_New_Family_of_Bi_Tri_Tetra_and_Pentanuclear_Ferric_Complexes/3329425
Nine members of a new family of polynuclear ferric complexes have been synthesized and characterized. The
reaction of Fe(O<sub>2</sub>CMe)<sub>2</sub> with polydentate Schiff base proligands (H<sub>2</sub>L) derived from salicylidene-2-ethanolamine,
followed in some cases by reaction with carboxylic acids, has afforded new complexes of general formulas [Fe<sub>2</sub>(pic)<sub>2</sub>(L)<sub>2</sub>] (where pic<sup>-</sup> is the anion of 2-picolinic acid), [Fe<sub>3</sub>(O<sub>2</sub>CMe)<sub>3</sub>(L)<sub>3</sub>], [Fe<sub>4</sub>(OR)<sub>2</sub>(O<sub>2</sub>CMe)<sub>2</sub>(L)<sub>4</sub>], and [Fe<sub>5</sub>O(OH)(O<sub>2</sub>CR)<sub>4</sub>(L)<sub>4</sub>]. The tri-, tetra-, and pentanuclear complexes all possess unusual structures and novel core topologies.
Mössbauer spectroscopy confirms the presence of high-spin ferric centers in the tri- and pentanuclear complexes.
Variable-temperature magnetic measurements suggest spin ground states of <i>S</i> = 0, 1/2, 0, and 5/2 for the bi-, tri-,
tetra-, and pentanuclear complexes, respectively. Fits of the magnetic susceptibility data have provided the magnitude
of the exclusively antiferromagnetic exchange interactions. In addition, an easy-axis-type magnetic anisotropy has
been observed for the pentanuclear complexes, with <i>D</i> values of approximately −0.4 cm<sup>-1</sup> determined from modeling
the low-temperature magnetization data. A low-temperature micro-SQUID study of one of the pentanuclear complexes
reveals magnetization hysteresis at nonzero field. This is attributed to an anisotropy-induced energy barrier to
magnetization reversal that is of molecular origin. Finally, an inelastic neutron scattering study of one of the trinuclear
complexes has revealed that the magnetic behavior arises from two distinct species.
2004-08-09 00:00:00
magnetization
antiferromagnetic exchange interactions
m össbauer spectroscopy
tri
polynuclear ferric complexes
pentanuclear complexes
O 2 CMe
H 2 L
CR
Pentanuclear Ferric Complexes
novel core topologies
polydentate Schiff base proligands