Formation of Novel 1‐D Chains by μ‐Amido Bridging of Dinuclear Manganese(III)‐Schiff Base Complexes

Abstract

Three novel neutral manganese(III) complexes of stoichiometry Mn(R-amsal-3,5-di-tBu)(H 2 O) n [H 3 -R-amsal-3,5-ditBu = 3-aza-4-(2-hydroxyphenyl)-N-(2-hydroxyphenyl)but-3-enamide; (R = H, 4-Me, 5-tBu)] have been synthesised using potentially trianionic and pentadentate Schiff-base ligands containing an amide group. Complexes were thoroughly characterised by elemental analysis, FAB mass spectrometry, infrared spectroscopy, magnetic susceptibility measurements and molar conductivities. Recrystallisation of these complexes from methanol yielded single crystals of [Mn 2 (amsal-3,5-di-tBu) 2 (MeOH) 2 ] n 1, [Mn 2 (4-Me-amsal-3,5-di-tBu) 2 -

Synthesis, characterization and antioxidant activity of water soluble MnIII complexes of sulphonato-substituted Schiff base ligands

“…1 H NMR spectra of tetragonal mononuclear Mn complexes with tetradentate Schiff base ligands symmetrically arranged in the equatorial plane show two up-field resonances around À20 to À25 ppm assigned to H4/ H4 0 and H5/H5 0 protons of the phenolato rings [44,[48][49][50]. A more complex pattern is observed in the 1 H NMR spectra of Mn complexes in which the ligand is not symmetrically arranged around the Mn ion because the different extent of charge transfer for protons of the phenolato trans to different groups results in the magnetic nonequivalence of protons of the two phenolato rings [44,51].…”

Self‐Assembly of Dimeric MnIII–Schiff‐Base Complexes Tuned by Perchlorate Anions

“…Main bond lengths and angles are listed in Table 3. [9,10,29] occupying the equatorial positions and giving rise to two six-membered chelate rings (which are nearly planar) and an additional five-membered chelate ring. The coordination sphere around each manganese centre is then completed by capping water molecules.…”

“…The interpretation of the data was based on previous findings for manganese(III) complexes with related Schiff-base ligands. [9,24] The spectra contain proton resonances that lie outside the diamagnetic region (δ = 0-14 ppm) due to the well-known isotropically shifting of the ligand protons for high-spin Mn III Crystals of H 4 L 10 suitable for X-ray studies were obtained by slow evaporation of a methanol solution of the ligand. The crystal structure, with the numbering scheme, is shown in Figure 1.…”

“…[9][10][11] The coordination chemistry of this species has been extensively studied [12,13] due to its rich redox behaviour, where manganese(III) complexes are the active sites of numerous [ the inner compartment of the Schiff base to the equatorial plane of the octahedron and by the binding of two water molecules in the axial positions. The octahedron entities are linked in pairs by µ-aquo bridges between neighbouring axial water molecules and also by π-π stacking interactions, establishing dimeric structures.…”

Novel peroxidase mimics: μ-Aqua manganese–Schiff base dimers

“…The interpretation of the data was based on previous findings for manganese(III) complexes with related Schiff base ligands [22,31,32]. The spectra contain between four and five proton resonances that lie outside the diamagnetic region (d = 0-14) due to the well-known isotropically shifting of the ligand protons for high-spin Mn(III) complexes in an octahedral field.…”