Structural Aspects and Spectroscopic Characterization of a Mn(II) Complex with Unsymmetrical NNO-Donor Hydrazone Ligand

Abstract

The manganese(II) complex, Mn[C5H4N–C(CH3)=N–N=C(O)–C6H5]2 (1) containing N,N,O-donor hydrazone ligand is characterized by X-ray diffraction study. The ligand is the 1:1 condensation product of benzhydrazide and 2-acetylpyridine. The spectral, cyclic voltammetric and room-temperature magnetic moment data are used to establish structure and electronic structure of the compound. Structural investigation shows that 1 crystallizes to a monoclinic system, space group C2/c, a = 22.8367(13), b = 10.1523(6), c = 12.0736(7) A, α = γ = 90°, β = 116.5930(10)°, and Z = 4. The central manganese atom is in an N4O2 coordination sphere constituted by the NNO donor sets of the two independently hydrazone ligands. The Mn–N1, Mn–N2 and Mn–O1 bond distances are 2.3255(15), 2.1854(13) and 2.1361(13) A, respectively. The effective magnetic moment (μeff) value of 1 is found to be 5.92 B.M. at 300 K. Cyclic voltammetry shows Mn(III)/Mn(II) couple at 0.9 V and imine reductions at −0.68 and at −1.3 V. Mn(II) complex of N,N,O-donor hydrazone ligand, Mn[C5H4N–C(CH3)=N–N=C(O)–C6H5]2 is characterized by single crystal X-ray diffraction technique, cyclic voltammetry and room-temperature magnetic moment data. Mn(II) is in an N4O2 coordination sphere, μeff is 5.92 BM and Mn(III)/Mn(II) couple appears at 0.68 V and imine reductions at −0.68 and at −1.3 V.