New trinuclear Schiff base complexes, Co–M–Co (M = Mn, Co), as molecular precursors for mixed oxides

Three new trinuclear symmetric derivatives of formula [Co2M(μ-salenph)2(μ-X)2] (salenph: N,N′-phenylenebis(salicylideniminato); 1, M = Mn, X = CH3COO−; 2, M = Mn, X = Cl−; 3, M = Co, X = CH3COO−), have been obtained by solvothermal reaction between [Co(salenph)] and the corresponding cobalt(II) or manganese(II) salts in ethanol. The complexes have been characterized by X-ray crystallography and magnetic susceptibility measurements. Complexes 1 and 3 are isomorphous and they show the X ligands bridging in opposite sides of the molecule having a trans coordination to the middle metal atom. On the contrary, compound 2 shows an unusual cis coordination of the chloride groups around the central manganese atom. The potential of the new complexes to act as single-source molecular precursors for mixed oxides is considered. The thermal decomposition of the three complexes indicates that they are completely converted to the crystalline spinel like oxides, Co3O4 and Co2MnO4. Magnetic properties of the obtained oxides have been investigated.

New heteronucleartrinuclear symmetric derivatives of formula [Co2Mn(m–salenph)2(m–X)2] have been obtained by solvothermal methods. The three metal atoms are collinear and they are bridged by the salen oxygen donor atoms and by the X ligands, giving rise to the presence of ferromagnetic interactions in the molecule. The ability of these species to act as single source precursors for mixed oxides has been studied and the formation of small size particles of the spinel type CoMn2O4 has been observed.Figure optionsDownload as PowerPoint slide