Preparation and characterization of different two types of di-mu-oxo dimanganese(IV) complexes with tetradentate Schiff bases

Novel di-mu-oxo dimanganese(IV) complexes with a series of tetradentate Schiff base ligands have been prepared and characterized by spectroscopy, magnetic susceptibility, electrochemical measurements and X-ray crystallography. The di-mu-oxo dimanganese(IV) complexes, [Mn-IV(mu-salophen)(mu-O)], 1 (salophen H-2 = N,N'-disalicylidene-1,2-diaminobenzene), [Mn(mu-salen)(mu-O)](2), 2 (salenH(2) = N,N'-disalicylidene-1,2-diaminoethane), [Mn(salen)(mu-O)](2), 3, [Mn(salipn)(mu-O)](2), 4 (salipnH(2) = N,N'-disalicylidene-1,2-diaminopropane) and [Mn(salbn)(mu-O)](2), 5 (salbnH(2) = N,N'-disalicylidene-1,4-diaminobutane), have been found to be obtained by the reaction of the tetradentate Schiff base ligands and potassium permanganate (KMnO4) in MeCN with stirring at room temperature. X-ray analysis revealed that these complexes are classified by two different types of di-mu-oxo manganese(IV) complexes in the coordination features of the ligands: one of them (1 and 2) has a structure in which salophen or salen ligands are coordinated to two manganese ions as a bridging bidentate ligand, whereas the other (3, 4 and 5) has a structure in which salen, salipn or salbn ligands are coordinated to each manganese ion as a tetradentate ligand. These types were characterized from their IR spectra around 650 cm(-1), UV-vis spectra and electrochemical properties. (C) 1997 Elsevier Science Ltd.