Crystallographic and computational electron density of d_x2-y2 orbitals of azo-schiff base metal complexes using conventional programs

The crystal structures of two azobenzene derivative Schiff base metal complexes (new C₄₄ H₄₀ CuN₆ O₂ of P-1 and known C₄₄ H₃₈ MnN₆ O₇ of P2₁ /c abbreviated as Cu and Mn, respectively) were (re-)determined experimentally using conventional X-ray analysis to obtain electron density using a PLATON program. Cu affords a four-coordinated square planar geometry, while Mn affords a hexa-coordinated distorted octahedral geometry whose apical sites are occupied by an acetate ion and water ligands, which are associated with hydrogen bonds. The π-π or CH-π and hydrogen bonding intermolecular interactions were found in both crystals, which were also analyzed using a Hirshfeld surface analysis program. To compare these results with experimental results, a density functional theory (DFT) calculation was also carried out based on the crystal structures to obtain calculated electron density using a conventional Gaussian program. These results revealed that the axial Mn-O coordination bonds of Mn were relatively weaker than the in-plane M-N or M-O coordination bonds.