Synthesis, crystal structures, and magnetic properties of methoxido-bridged dinuclear MnIII complexes derived from tri-dentate chelating ligands

Two new doubly methoxido-bridged Mn-III dinuclear complexes, [Mn-III(mphp)(-OCH3)(CH3OH)](2)2CH(3)OH (1) and ([Mn-III(ahbz)(-OCH3)(CH3OH)](2)2CH(3)OH (2), have been synthesized by using the tridentate ligands H(2)mphp (H(2)mphp=2-methyl-6-(pyrimidin-2-yl-hydrazonomethyl)-phenol) and H(2)ahbz (H(2)ahbz=N-(2-amino-propyl)-2-hydroxy-benzamide). The complexes have been characterized by single-crystal X-ray diffraction analysis and magnetic measurements. Complexes 1 and 2 have a similar dimeric molecular structure. Two [Mn(L)(CH3OH)](+) moieties (L2-=mphp(2-) or ahbz(2-)) are bridged by two -OCH3- groups in the axial-equatorial asymmetric manner. The coordination geometry of Mn-III is an axially elongated octahedron with two oxygens of a methanol ligand and a methoxido ligand situated at the axial positions. Magnetic measurements indicate that 1 and 2 exhibit antiferromagnetic behavior with the fitting parameter of J=-1.49(3)cm(-1), D=-1.3(1)cm(-1), g=1.98(1) and zJ=-0.18(4)cm(-1) for 1, and J=-1.6(2)cm(-1), D=4.5(3)cm(-1), g=2.06(1) and zJ=1.4(1)cm(-1) for 2 on the basis of the spin Hamiltonian =-2JS(Mn1)S(Mn2).