NMR and UV spectroscopic characterization on the solution behavior of heterotrinuclear transition-metal complexes [(Fe2MO)-M-II-O-I(OOC2H5)(6)L-3] (M= Co, Ni, Mn; L = C5H5N, H2O)

A series of new heterotrinuclear transition-metal complexes [(Fe2MO)-M-I-O- I(OOCC2H5)(6)L-3] (M = Co, Ni, Mn; L = C5H5N, H2O) were synthesized and cha racterized. Their structures and dynamics in different solutions and temper atures were investigated by NMR and UV. Assignments of the H-1 NMR spectra were made on the basis of relative intensities, broadening, substitution wi th appropriate ligands and spin-lattice relaxation. Experimental results sh ows that there is antiferromagnetic exchange interaction among the three me tal ions within M3O core. It is found that these complexes in DMSO, CD3CN, CDl(3) and CD3COCD3 solvents are stable at room temperature and their struc tures in solution are the same as their crystal ones. However, the complexe s decomposed into carboxylic acid, pyridin and metal ions in water. The res ults may be helpful in guiding synthesis of similar complexes.