Potentially hexadentate N2O4 donor Schiff base ligands N,N'-bis(3-ethoxysalicylidenimino)-1,2-diaminoethane ((LH2)-H-1) and N,N'-bis(3-methoxysalicylidenimino)-1,3-diaminopropane ((LH2)-H-2) have been used to synthesize two manganese(III) compounds [MnL1(SCN)(H2O)].[MnL1(H2O)(2])(ClO4)center dot CH3CN (1) and MnL2(SCN)(H2O)] (2). All the ligands and the complexes have been characterized by microanalytical and spectroscopic techniques. The X-ray structural characterization of all the complexes shows a tetragonally elongated octahedral geometry for the manganese coordination sphere. The octahedron entities are further connected in pairs through intermolecular hydrogen bonding to form mu-aquo dimers, which are further stabilized by pi-pi interactions occurring between the aryl rings of the Schiff base ligands. These noncovalent interactions have been investigated in terms of energies and geometries using theoretical calculations. The catalytic activity of compounds 1 and 2 on the oxidation of 3,5-di-tert-butylcatechol was determined spectrophotometrically by monitoring the increase of the 3,5-di-tert-butyl-o-benzoquinone characteristic absorption band at about 400 nm over time in methanol saturated with O-2. The complexes were able to oxidize 3,5-di-tert-butylcatechol to the corresponding o-quinone with distinct catalytic activity. (C) 2014 Elsevier Ltd. All rights reserved.