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

Two neutral complexes [(L₆³4M)Fe₂Cl ₄]·2H₂O·2CHCl₃ (1) and [(L ₆³4M)Mn₂Cl₄]·CH ₃CN (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 CH ₂Cl₂, whereas only 2 is stable in CH₃CN. On the contrary, 1 is in equilibrium with another Fe^II species in CH ₃CN. 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 Fe^III 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.