Odd-numbered Fe(III) complexes: synthesis, molecular structure, reactivity, and magnetic properties.
Three isostructural disklike heptanuclear FeIII compounds of the general formula [FeIII7(mu3-O)3(L)3(mu-O2CCMe3)6(eta1-O2CCMe3)3(H2O)3], where L represents a di- or triethanolamine moiety, display a three-blade propeller topology, with the central Fe atom representing the axle or axis of the propeller. This motif corresponds to the theoretical model of a frustrated Heisenberg star, which is one of the very few solvable models in the area of frustrated quantum-spin systems and can, furthermore, be converted to an octanuclear cage for the case where L is triethanolamine to give [FeIII8(mu4O)3(mu4-tea)(teaH)3(O2CCMe3)6(N3)3].1/2MeCN.1/2H2O or [FeIII8(mu4O)3(mu4-tea)(teaH)3(O2CCMe3)6(SCN)3].2MeCN when treated with excess NaN3 or NH4SCN, respectively. The core structure is formally derived from that of the heptanuclear compounds by the replacement of the three aqua ligands by an {Fe(tea)} moiety, so that the 3-fold axis of the propeller is now defined by two central FeIII atoms. Magnetic studies on two of the heptanulcear compounds established unequivocally S = 5/2 spin ground state for these complexes, consistent with overall antiferromagnetic interactions between the constituent FeIII ions.
Ako
Ayuk M
AM
Institut für Anorganische Chemie der Universität Karlsruhe, Engesserstrasse Geb. 30.45, D-76128 Karlsruhe, Germany.
Waldmann
Oliver
O
Mereacre
Valeriu
V
Klöwer
Frederik
F
Hewitt
Ian J
IJ
Anson
Christopher E
CE
Güdel
Hans U
HU
Powell
Annie K
AK
D005290:Ferric Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D008280:Magnetics; D015394:Molecular Structure; D011789:Quantum Theory; D013329:Structure-Activity Relationship
D005290:Ferric Compounds; D046911:Macromolecular Substances