Metal Complexes With Tetrazole-containing Ligands: Synthesis, Structures And Properties

The rational design of metal-organic coordination architectures with desired functions are one of the most active fields in current coordination chemistry, due to their intriguing structures and potential applications. However, the theoretical forecasting of the structures and functions of such complexes is still difficult because their structures might be influenced by many factors. Therefore, it is still necessary to study the synthesis and structures of complexes by design and selection of suitable ligands, anions and other factors, as well as the relationships among them.The ligands containing tetrazolate groups have been demonstrated to be good bridging ligands due to their diverse coordination modes. In this dissertation, eight tetrazole-containing ligands and their thirty-one complexes with various structures have been synthesized and characterized. Several factors, such as the nature of metal ions, the properties of ligands, reaction conditions and other factors were found to greatly influence the structures of the complexes. Furthermore, luminescent, magnetic and solid-state circular dichroism (CD) properties of some complexes have also been studied. The main contents are summarized as follows:1. The 5-aminotetrazolate (5-HATZ) ligand and its seven d¹⁰ metal complexes have been synthesized and structurally characterized. The influences of the metal ions, the reaction conditions and the second ligands on the formation of coordination frameworks are discussed. The 5-aminotetrazolate (5-HATZ) bonds to metal ions inμ₃ andμ₄ coordination modes in these complexes. In addition, luminescent properties of some complexes have also been studied.2. Two tetrazole-containing ligands have been designed and synthesized, and their ten complexes have been synthesized and structurally characterized. The analysis of the structures of these complexes shows that the tetrazolate rings of the ligands bond to metal ions inμ₂ andμ₃ coordination modes. In addition, luminescent, magnetic and the solid-state circular dichroism (CD) spectral properties of some complexes have also been studied. 3. Four structure related flexible di-tetrazole ligands with different spacers and five complexes with d¹⁰ metal ions have been synthesized and characterized. The effects of some factors such as the properties of ligands, the nature of metal ions as well as the reaction conditions on the structures of the complexes have been discussed, and the luminescent properties of ligands and complexes were investigated. The results indicate that the tetrazolate rings of the ligands could act as either monodentate or multidentate ligands when bonding to metal ions under different conditions, and the ligands are deprotonated to form bivalent anionic derivatives in the obtained complexes. The ligands and their complexes exhibit fluorescence emissions.4. Two thiother ligands with tetrazole-containing group and their nine complexes were synthesized and characterized. The influences of the non-coordination groups of the ligands, the metal ions, the anions and the solvents on the coordination structures are discussed. The weak interactions such as C-H…N and C-H…Cl in these complexes greatly affect the packing modes of the molecules in the crystal, and stabilize the solid structures of these complexes. In addition, luminescent properties of some complexes have also been studied.