Synthesis, structure and characterizations in solid state and solution of dinuclear pentacoordinated FeII and MnII complexes and of a linear tetranuclear FeIII complex obtained with the ligand N,N,N′,N′-tetrakis-[(6-methyl-2-pyridyl)methyl]propane-1,3-diamine

Two neutral complexes [(L(6)(3)4M)Fe2Cl4].2H(2)O.2CHCl(3) (1) and [(L(6)(3)4M)Mn2Cl4].CH3CN (2) have been synthesized [L(6)(3)4M = N,N,N',N'-tetrakis[(6-methyl-2-pyridyl)methyl]propane-1,3-diamine] and their molecular structures established by X-ray crystallography. Both structures are similar, with each metal center in a trigonal-bipyramidal environment. No magnetic coupling is observed between the metal centers. UV/Vis spectra and cyclic voltammograms were recorded in CH2Cl2 and CH3CN solutions. Both complexes are stable in CH2Cl2, whereas only 2 is stable in CH3CN. On the contrary, I is in equilibrium with another Fen species in CH3CN. When this last solution is aerated, monocrystals of the neutral linear tetranuclear complex [(L(6)(3)4M)Fe-4(mu-O)(3)Cl-6].2CH(3)CN (3) can be isolated. Its structure is unusual with two Fen, ions penta-coordinate and the two others tetracoordinate with only chloro ligands and oxo bridges. The magnetic properties reveal that two consecutive metal centers are strongly antiferromagnetically coupled. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.