Synthesis, crystal structure, and properties of a seven-coordinate manganese(II) complex formed with the tripodal tetradentate ligand tris (N -methylbenzimidazol-2-ylmethyl)amine and salicylate

Abstract

A seven-coordinate manganese(II) complex with the tripod tetradentate ligand tris(N-methylbenzimidazol-2-ylmethyl)amine (Mentb), [Mn(Mentb)(salicylate)(DMF)](ClO₄) ⋅ (DMF), was synthesized and characterized by elemental, electrical conductivity, infrared, and UV-Vis spectral measurements. The crystal structure of the complex has been determined by single-crystal X-ray diffraction. Mn^II is bonded to a Mentb, a salicylate and dimethylformamide through four nitrogens and three oxygens, resulting in seven-coordination. Cyclic voltammograms of the complex indicate a quasi-reversible Mn³⁺/Mn²⁺ couple. The X-band electron paramagnetic resonance spectrum exhibits a six-line manganese hyperfine pattern with g = 2, A = 93, confirming that the material is high-spin Mn(II).

Keywords:

• Manganese(II) complex
• Crystal structure
• Cyclic voltammetry
• EPR
• tris(N-methylbenzimidazol-2-ylmethyl)amine

Acknowledgments

The authors acknowledge the financial support and grant from “Qing Lan” Talent Engineering Funds and Students’ Science and Technology Innovation Funds (grant no. DXS2010-040) by Lanzhou Jiaotong University. The grant from “Long Yuan Qing Nian” of Gansu Province also is acknowledged. This study was also supported by the open foundation of key laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Northwest University.