Ferromagnetic Dinuclear Mixed-Valence Mn(II)/Mn(III) Complexes: Building Blocks for the Higher Nuclearity Complexes. Structure, Magnetic Properties, and Density Functional Theory Calculations

Abstract

A series of six mixed-valence Mn(II)/Mn(III) dinuclear complexes were synthesized and characterized by X-ray diffraction. The reactivity of the complexes was surveyed, and structures of three additional trinuclear mixed-valence Mn(III)/Mn(II)/Mn(III) species were resolved. The magnetic properties of the complexes were studied in detail both experimentally and theoretically. All dinuclear complexes show ferromagnetic intramolecular interactions, which were justified on the basis of the electronic structures of the Mn(II) and Mn(III) ions. The large Mn(II)-O-Mn(III) bond angle and small distortion of the Mn(II) cation from the ideal square pyramidal geometry were shown to enhance the ferromagnetic interactions since these geometrical conditions seem to favor the orthogonal arrangement of the magnetic orbitals.

Experimental and Computational Study of Unique Tetranuclear µ3‐Chloride and µ‐Phenoxo/Chloro‐Bridged Defective Dicubane Cobalt(II) Clusters

“…The coordination mode of the ligands L1 and L2 in 1 and 2 resembles those previously observed by us in mixed‐valence manganese species [Mn II Mn III (µ‐L)(µ‐OR)Cl 2 D] (L = L1 or L2 , R = Me or Et, and D = MeOH or EtOH) 8b. In these complexes, the diaminobisphenolates act as bridging ligands between metal centers, but produce dinuclear complexes instead of tetranuclear ones.…”

“…All syntheses were performed under the ambient laboratory atmosphere. Ligands H 2 L1 and H 2 L2 were synthesized according to the literature 22. Elemental analyses were carried out by using a Vario El III elemental analyzer.…”

A New Mixed-Valence Mn(II)Mn(III) Compound With Catalase and Superoxide Dismutase Activities

“…The very weak ferromagnetic coupling ( J 2 ) is attributed to exchange via the di-OR bridge. The Mn-OR-Mn angles were found to be 97.84° and 103.21°, with a Mn-O-O-Mn torsion angle of 156.56°, which is consistent with ferromagnetic exchange (Gelasco et al, 1997 ; Wittick et al, 2004 ; Naiya et al, 2012 ; Hänninen et al, 2013 ). Similar structural features have also been observed in a set of di- and trinuclear mixed valence manganese complexes (Hänninen et al, 2013 ).…”

“…The Mn-OR-Mn angles were found to be 97.84° and 103.21°, with a Mn-O-O-Mn torsion angle of 156.56°, which is consistent with ferromagnetic exchange (Gelasco et al, 1997 ; Wittick et al, 2004 ; Naiya et al, 2012 ; Hänninen et al, 2013 ). Similar structural features have also been observed in a set of di- and trinuclear mixed valence manganese complexes (Hänninen et al, 2013 ). The ferromagnetic coupling constants of the dinuclear complexes were found in the range of +2.15(6) to +7.9(7) cm −1 , whereas a much smaller coupling constant of +0.04(7) cm −1 was observed in the case of one of the trinuclear complexes.…”

Two C3‐Symmetric Dy3III Complexes with Triple Di‐μ‐methoxo‐μ‐phenoxo Bridges, Magnetic Ground State, and Single‐Molecule Magnetic Behavior

“…Dy(NO 3 ) 3 ⋅ 6 H 2 O was precipitated from the solution during the cooling in a refrigerator. Ligand H 2 L was synthesized according to the literature 28…”