Polyiron(III)-Alkoxo Clusters: a Novel Trinuclear Complex and Its Relevance to the Extended Lattices of Iron Oxides and Hydroxides

Abstract

The solid-state molecular structure of I consists of a triangular array of iron(III) ions connected by a triply bridging methoxide and three /^-methoxide ligands. The oxygen donors of a monodentate methoxide and of a chelating dbm ligand complete the coordination sphere of each metal ion. The resulting mononegative Fe3(/i3-OCH3)(,M2-OCH3)3(OCH3)3(<ibm)3 moiety coordinates the K counterion through the oxygens of the /z2-OCH3 ligands. The oxygen atoms in the core of I are arranged in two essentially parallel layers and display a closest-packing which is found in iron oxides and hydroxides. The highspin iron(III) ions are antiferromagnetically coupled with an S = '/2 spin ground state. Assumption of a C2i point-group symmetry for the cluster leads to a satisfactory reproduction of the observed magnetic behavior with g = 2.0 and either J = 10.6(1),/= 15.3(2) cm-1 or J= 12.9(2), J' = 9.7(1) cm-1, where the spin-only Heisenberg Hamiltonian is defined as H = and / is the unique coupling constant. The relative contributions of geometrical distortions and of antisymmetric exchange to the splitting of the 4-fold 2E electronic ground state of an idealized system with trigonal symmetry have been estimated from X-band EPR spectra recorded on powdered samples.

High-Nuclearity Manganese and Iron Complexes with the Anionic Ligand Methyl Salicylimidate

“…13 Structurally, the [Fe 10 O 18 ] cores of these molecules can be considered as fragments of an iron oxide (wustite) or hydroxide (lepidocrocite) phase: the oxygen atoms of the cores are arranged in cubic close-packed layers with the iron atoms occupying the octahedral interstices. 48 Another complex worth mentioning here is a Ti 10 O 32 cluster that is analogous to 5. 49 Magnetism.…”

Group 10 Metal Aminopyridinato Complexes: Synthesis, Structure, and Application as Aryl-Cl Activation and Hydrosilane Polymerization Catalysts

“…Such mixed alkaline metal transition metal quarters are known for Zn, 26 Tc, 27 Mo, 28 Cr, 29 and Fe. 30 We propose ether cleavage in the course (5), Ni1-N2 2.093(6), Ni1-O1 2.018(4), Ni1-O3 2.026(4), Ni1-O4 2.045(5), Ni2-O2 2.013(4), Ni2-O3 2.011(5), Ni2-O4 2.049(6), Ni2-N3 2.011(5), Ni2-N4 2.071(6), Ni3-O1 2.018(5), Ni3-O2 2.028(4), Ni3-O4 2.054(5), Ni3-N5 2.001(5), Ni3-N6 2.077(5), O1-Li 1.908(13), O2-Li 1.918(13), O3-Li 1.897 (12); O1-Li-O2 93.2(5), O1-Ni3-O2 86.75 (18), Ni1-O4-Ni2 97.7(2), Ni1-O1-Ni3 99.59 (19), O3-Ni1-O4 80.9(2), N1-Ni1-N2 65.9(2). of the synthesis of 6 and 7 and a protonation of some of the lithiated aminopyridinato ligands.…”

Diffusion inélastique des neutrons sur les aimants moléculaires

“…Un travail récent de "fonctionalisation" de ces matériaux moléculaires a été entrepris notamment sur des surfaces [34,70,100], ou par organisation en films de LangmuirBlodgett [45,46,102]. En parallèle les aimants moléculaires sont des systèmes modèles pour l'étude de certaines fonctions biologiques (transport d'oxygène [19,25,56,93], activité enzymatique [43,126,127]). Le champ d'intervention des agrégats moléculaires est donc large : de systèmes modèles pour le magnétisme quantique ou certaines fonctions biologiques aux développements de l'électronique moléculaire.…”