Abstract
The crystal structures of two azobenzene derivative Schiff base metal complexes (new C44H40CuN6O2 of P-1 and known C44H38MnN6O7 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.
Highlights
Molecules 2021, 26, 551. https://X-ray crystal structure analysis is powerful as a means of determination of structures as well as a means of measurement of charge density for chemical substances in the solid state
In X-ray crystal structure analysis, in principle, atoms are located and assigned in the places indicating high electron densities from the Fourier transferred data obtained by experiments to build and refine structural models [3], which results in empirical evaluation of bond lengths and intermolecular interactions [4]
In the electron density distribution map from the crystal structures, the shape of the orbital of the central metal cannot be seen, and a specialized program is required, but valence electrons and d-orbitals can be displayed by performing quantum chemistry calculations
Summary
X-ray crystal structure analysis is powerful as a means of determination of structures as well as a means of measurement of charge density for chemical substances in the solid state. From the obtained electron density, the state of the covalent bonds and coordinate bonds and the characteristics of intramolecular/intermolecular interactions can be clearly estimated. High-resolution structural analysis has been employed for valence electrons and charge transfer around metal sites in these proteins [1,2]. In X-ray crystal structure analysis, in principle, atoms are located and assigned in the places indicating high electron densities from the Fourier transferred data obtained by experiments to build and refine structural models [3], which results in empirical evaluation of bond lengths and intermolecular interactions [4]. With the development of Hirshfeld surface analysis, it is possible to know the breakdown of intermolecular interactions in a crystal packing [5] especially for crystalline organic compounds [6] using freely available programs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
