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

Abstract : Two neutral complexes [(L634M)Fe2Cl4]*2H2O*2CHCl3 (1) and [(L634M)Mn2Cl4]*CH3CN (2) have been synthesized {L634M = 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, 1 is in equilibrium with another FeII species in CH3CN. When this last solution is aerated, monocrystals of the neutral linear tetranuclear complex [(L634M)Fe4(μ-O)3Cl6]*2CH3CN (3) can be isolated. Its structure is unusual with two FeIII ions pentacoordinate 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. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)