Synthesis, Characterization And Properties Of Transition Metals And Rare Earth Complexes With C₄H₉N₁₁O Ligand

Tetrazole compounds are a series of important high-nitrogen energetic compounds and used as gas generating agent, energetic binder in solid propellants and low sensitivity initiating explosives. Additionally, they are able to participate in multi-coordination modes with metal ions in the complexes through some nitrogens processing lone electron pair. So we can obtain some complexes with excellent properties. Bis(1-methyl-tetrazol-5-yl)-triazene monohydrate (C₄H₇N₁₁·H₂O) was choosed as ligand and applied to synthesize its transition metal and rare earth complexes. Meanwhile, properties of transition metals and rare earth Complexes with C4H9N11O ligand ware carried on preliminary discussion.The main work is as follows:According to the reference, bis(1-methyl-tetrazol-5-yl)-triazene monohydrate was synthesized and characterized by melting test, elemental analysis and IR spectroscopy to prove the success of the experiment.Twelve transition metal and rare earth bis(1-methyl-tetrazol-5-yl)-triazenate complexes were prepared by the reaction of sodium bis(1-methyl-tetrazol-5-yl)-triazenate with transition metal and rare earth nitrate. Their structures were determined by elemental analysis, IR, UV-Vis and thermal analysis. The molecular structural formulas of the complexes can be described as Cu(C₄H₆N₁₁)₂(H₂O)₂, [Mn(H₂O)₆](C₄H₆N₁₁)₂·2H₂O, Zn(C₄H₆N₁₁)₂(H₂O)₂, Co(C₄H₆N₁₁)₂, Ni(C₄H₆N₁₁)₂, Pb(C₄H₆N₁₁)₂ and RE(C₄H₆N₁₁)₃(H₂O)₂·4H₂O (RE = La,Ce,Pr,Nd,Sm and Eu), respectively.The single crystals of copper and manganese complexes were obtained from the solvent evaporation method. Their structure were confirmed by X-ray single-crystal diffraction. Copper complex is a mononuclear complex that the central ion Cu(II) is coordinated with two N atoms from two bis(1-methyl-tetrazol-5-yl)-triazenate anion and two O atoms from two water. Bis(1-methyl-tetrazol-5-yl)-triazenate anion acts as monodentate ligand. Manganese complex is also mononuclear complex that the central ion Mn(II) is coordinated with six O atoms from six H2O. Whereas bis(1-methyl-tetrazol-5-yl)-triazenate anion only acts as external anion.The thermogravimetric analysis was carried out to assess their thermal stability for twelve complexes at heating rates of 5℃/min, 10℃/min and 15℃/min, respectively. Meanwhile, the kinetic parameters of their main thermal decomposition stage were calculated using the Kissinger method and Ozawa method. The results showed that apparent activation energies of transition metal complexes have erratic relation to atomic number. However, the relationship between apparent activation energies of rare earth complexes and atomic number of rare earth is consistent with tetrad effect of rare earth. Based on TG-DTG and DSC curves, the lead complex has the best thermal stability among transition metal complexes. Thermal stabilities of rare earth complexes, which are similar, are improved compared with those of transition metal complexes.