3,3'-DIHYDROXY-4,4'-[1,2-CYCLOHEXANEDIYL BIS(NITRILOMETHYLIDYNE)]-BIS-PHENOL SCHIFF-BASE AND ITS Mn(II) COMPLEX: SYNTHESIS, EXPERIMENTAL AND THEORETICAL CHARACTERIZATION
H. Eshtiagh-Hosseini1, S.A. Beyramabadi2, M. Mirzaei1, A. Morsali2, A.R. Salimi1, M.A. Naseri3
1Ferdowsi University of Mashhad, Mashhad, Iran
2Mashhad branch, Islamic Azad University, Mashhad, Iran
3Birjand University, Birjand, Iran
Keywords: Schiff base, salen, Mn, DFT, IR assignment, NMR, cyclohexanediyl
Abstract
In this work, a 3,3'-dihydroxy-4,4'-[1,2-cyclohexanediyl bis (nitrilomethylidyne)]-bis-phenol [=H2L] Schiff-base ligand and its Mn(II) complex [Mn(L)(H2O)2] are newly synthesized and characterized by elemental analysis, IR and NMR spectroscopies. Also the geometry optimizations, assignment of the IR bands and NMR chemical shifts are computed using the density functional theory (DFT) method. The DFT optimized geometry of the ligand is not planar; each of the cyclohexane and two benzene rings are located in separate planes. The phenolic protons are engaged in the intramolecular-hydrogen-bonding interactions with azomethine nitrogen atoms. In the optimized geometry of the octahedral Mn2+ complex, the dianionic L2– acts as a tetradentate ligand in the N, N, O–, O– manner, where the coordinating atoms occupy the four equatorial positions. The two axial positions are occupied by two H2O ligands. The theoretical and experimental results are in good agreement, confirming the validity of the optimized geometries for the H2L ligand and its Mn complex.
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