Synthesis, Characterization and Catalytic Features and Crystal Structure of Mn(II) Complex With a tetradentate Salen ligand

The Schiff bases and their complexes have played an important role in the development of coordination chemistry biological and material science. Schiff base ligands stabilize different metal ions to yield metal complexes with a variety of properties and applications. For instance, the chelating salen, is known by the ability to significantly decrease the redox potentials, and the resulting complexes constitute suitable systems to catalyse multiple redox reactions such as asymmetric epoxidation of unfunctionalized olefins, catalase reaction [1,2], water photolysis[3],Diels-Alder cycloaddition, enantioselective cyclopropanation of styrene and ring opening of epoxides [4-7]. In this work, we describe the synthesis of a new mononuclear complex of manganese (II),viz,[MnL(OAc)2].3H2O containing the corresponding N-donor Schiff base ligand. A mononuclear Mn (II) Complex, [MnL(OAc)2].3H2O has been derived tetra dentate salen, N,N’-bis(phenyl(pyridine-2-yl)methylene)ethane-1,2-diamine (L) . The molecule was characterized by elemental analysis, FT-IR, and single-crystal X-ray crystallography. The complex crystallized in the monoclinic space group C2/c with unit cell dimensions a=24.4771(6) Å, b=8.0621(2) Å, c=30.5018(8) Å, α = 90̊ , β =97.437(2) ̊, γ =90̊ ,V= 5968.5(3) Å3, Z = 8, R1 = 0.0336, and wR2 =0.0404. In the crystal structure of complex the Mn (II) with four coordinated nitrogen atoms and two acetate ions has a distorted cubic geometry. Three water molecule are also incorporated in the crystal network. Several hydrogen bonds present in the crystal structure. Oxidation reactions carried out on styrene and revealed that the complex compound was good and effective catalyst for styrene oxidation. Comparison between neat and complex catalyzed reactions proves that the oxidation reactions using catalysts give higher conversions than their corresponding neat reactions.