One-dimensional manganese(II) complex with only end-to-end azide ligands: Crystal structure and magnetic characterization

Effective catalytic disproportionation of aqueous H2O2 with di- and mono-nuclear manganese(II) complexes containing pyridine alcohol ligands

The two novel manganese(II) complexes with 2-hydroxymethylpyridine (2-CH2OHpy) {[Mn2(μ-Cl)2(2-CH2OHpy)4]Cl2·2H2O (1)} and 2-hydroxyethylpyridine (2-(CH2)2OHpy) {[Mn(2-(CH2)2OHpy)2(NCS)2] (2)} were synthesized and characterized by means of X-ray diffraction, IR, EPR, HF EPR spectroscopy, magnetic and TG/DTG data. The complexes show catalase-like activity in neutral aqueous solution since they were able to disproportionate H2O2 to harmless H2O and O2. Both complexes act as true catalysts since they reverted to their original form after depleting all the H2O2, as suggested by the operando resonant inelastic X-ray spectroscopy (RIXS) measurements.

Eight- and six-coordinated Mn(II) complexes of heteroaromatic alcohol and aldehyde: crystal structure, spectral, magnetic, thermal and antibacterial activity studies

Crystal, molecular and electronic structure of new manganese(II) compounds: [Mn(2-CH2OHpy)2(NO3)2] (1), [Mn(4-CHO-5-MeIm)2(NO3)2] (2) and [Mn(4-CHO-5-MeIm)2Cl2] (3), where 2-hydroxymethylpyridine (2-CH2OHpy) and 5(4)-carbaldehyde-4(5)-methylimidazole (5(4)-CHO-4(5)-MeIm), have been characterised using X-ray, spectroscopic, magnetic and TG/DTG data. In compounds 1 and 2, the Mn(II) ion is eight-coordinated forming distorted pseudo-dodecahedron, that is rather unusual for the manganese(II) complexes, whereas in 3 the Mn(II) ion environment is a distorted octahedron. The high coordination number (CN=8) of 1 and 2 results from bidentate character of the nitrate ligands. The X-band EPR spectra of compounds 2 and 3 exhibit fine structure signals resulting from zero-field splitting (ZFS) of the spin states for high spin d(5) Mn(II), whereas for 1 the broad isotropic signals were observed. The estimation of ZFS for individual Mn(II) ions was carried out for all compounds using DFT calculations. The free ligands and their manganese(II) complexes have been tested in vitro against gram-positive and gram-negative bacteria in order to assess their antimicrobial properties.

A novel single-site manganese(II) complex of a pyridine derivative as a catalase mimetic for disproportionation of H2O2 in water

A novel single site Mn(II) complex was successfully synthesized and tested in the aqueous disproportionation of hydrogen peroxide. The complex was found to be stable (HR-XAS) and exhibits catalase-like activity in neutral pH. Theoretical calculations suggested a reaction mechanism involving two complexes, changes in metal oxidation state and proton shuttling.