In this project, coordination compounds containing two categories of pincer ligand of pyridine-2,6-dicarboxylic acid (pydc) and pyridine-2,6-dicarboxamide, with capability of chelating tridentate mode were investigated. In the first section, the structural chemistry of the large society of 736 coordination compounds containing pydc was investigated. The various parameters were used for investigation of this huge category of compounds which include the kind of metal center, oxidation state of metal ion, coordination number, coordination mode of pydc ligand, auxiliary ligand (coligand) and counterion species, and type of complex structures (e.g. monomer, dimmer,…). The systematic classification (taxonomy) of the diverse variety of these compounds to five classes based on the homo or heteroleptic coordination sphere and the charge of complexes was performed. The general statistical results presented as the following points: the kind of metal ion (55 cases), coordination mode of pydc (44 cases), coordination number of metal (4 to10), structure type (monomer to polymer), classes (I-V) and coligand and/or counter ions (182 cases). The results indicated special structural features of each class, which led to the regular chemical rules for synthesized compounds.
In the second section, seven metal complexes with pyridine–2,6–dicarboxylate ligand were prepared with various cations or coligands. These compounds were characterized by infra red, CHN microanalysis and X-ray structural studies along with a detailed analysis of Hirshfeld surface and 2D fingerprint plot as an assisting tool for decoding of the intermolecular interactions. Also, in order to get deeper understanding within coordination environment of Cu complexes, bond order indexes were utilized by DFT method.
In the third part, based on the design by modifying the functional group of carboxylic acid to carboxamide, the syntheses and characterizations of three pyridine-2,6-dicarboxamide ligands with 2-mainopyrimidine (L1H2), 2-amino-4-methylpyrimidine(L2H2) and 2-amino-4,6-dimethyl pyrimidine (L3H2) were performed. The effect of functional group type and addition of methyl substituent in three dicarboxamide ligands were considered in the molecular and crystal structures. Coordination behavior of these ligands in neutral and anionic forms were studied on the seven metal complexes of Cu(II), Ni(II), Co(II) and Hg(II) metal centers. Global and local reactivity indexes such as Fukui functions related to anionic, neutral ligands and copper coordination compounds were computed by conceptual DFT method (CDFT). The theoretical results on the reactivity of ligands were in good agreement with the experimental data. |
