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

Abstract

Two new doubly methoxido-bridged MnIII dinuclear complexes, [MnIII(mphp)(μ-OCH3)(CH3OH)]2·2CH3OH (1) and ([MnIII(ahbz)(μ-OCH3)(CH3OH)]2·2CH3OH (2), have been synthesized by using the tridentate ligands H2mphp (H2mphp = 2-methyl-6-(pyrimidin-2-yl-hydrazonomethyl)-phenol) and H2ahbz (H2ahbz = 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− = mphp2− or ahbz2−) are bridged by two μ-OCH3− groups in the axial-equatorial asymmetric manner. The coordination geometry of MnIII 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 Ĥ = −2JŜMn1ŜMn2.