A theoretical study of intramolecular H-bonding and metal-ligand interactions in some complexes with bicyclic guanidine ligands

作者：Chahkandi Mohammad^*; Khoshbakht Behnaz Madani; Mirzaei Masoud^*

来源：Computational and Theoretical Chemistry, 2016, 1095: 36-43.

DOI：10.1016/j.comptc.2016.09.014

• Intramolecular hydrogen bond
• hppH
• NBO
• Charge transfer
• TD-DFT

The reported complexes formulated as [MnCl2(hppH)(2)] (1), [FeCl2(hppH)(2)],(2), and [NiCl2(hppH)(2)] (3) and a new theoretically designed example, [CuCl2(hppH)(2)] (4), have been used for calculations at the B3LYP/ LANL2DZ/6-311G (d, p) level of density functional theory (DFT). The intramolecular hydrogen bonds (HB) N-H center dot center dot center dot Cl could followed through their physicochemical properties such as, vibrational frequency, electronic transmission in UV-Visible spectroscopy, metal-ligand donor-acceptor interactions in NBO analysis, total energy and frontier molecular orbital energy. These properties influenced by the relationship of structure and metal-ligand electron density exchange will be discussed. The computations revealed that the stronger N-H center dot center dot center dot Cl HB exists in complexes with longer M-Cl and M-N-imine bonds and shorter H center dot center dot center dot Cl bond, and vice versa that confirms the shortest and longest HBs in 4 and 3, respectively. These results agree with the second-order perturbation energies obtained by NBO analysis within charge transfer from the proton-acceptor chlorine to the p* orbital of the N atom. The calculated electronic absorption spectra by TD-DFT calculations show the larger Cl- to M2+ donation in 2 and 3 in comparison with I and 4 that confirms the stronger HB in 1 and 4 compared to 2 and 3. In order to find the basis set effect on the structure, vibrational frequencies, and electronic transitions, we use another basis set def2-TZVP includes polarization function for Mn element in complex 1. The obtained test results showed unremarkable differences between two basis sets LANL2DZ and def2-TZVP (cf. Figs. S2, S3 and Tables S1 and S2 in Supplementary Materials).

• 出版日期2016-11-1