Structural Characteristics and Decomposition Mechanism of 1,1''-Dimethyl-5,5''-Azotetrazole

The geometry and the potential curve of thermal decomposition for 1, 1' dimethyl-5, 5'-azotetraol (1-DMAT) are calculated by ab initio quantum chemistry method. The structural characteristics and decomposition mechanism are carefully studied. It is found that the terrazzo ring satisfies 4n 2 rule and it is a conjugated π-system for 1-DMAT. The azotetrazol has aromatic characteristic and its thermal decomposition can proceed in two steps: ring opening and separation N2. The activation energies of the two steps are 243.5 kJ/mol and 64.01 kJ/mol, respectively. The ring opening is the rate-controlling step.     

Structural Characteristics and Decomposition Mechanism of 2,2′-Dimethyl-5,5′-Azotetrazole

The geometry and the potential curve of thermal decomposition for 2,2′dimethyl-5,5′-azotetraol (2-DMAT) are calculated by ab initio quantum chemistry method. The structural characteristics and decomposition mechanism are carefully studied. It is found that the terrazzo ring satisfies 4n+2 rule and it is a conjugated π-systems for 2-DMAT. The azotetrazol has aromaic characteristic and its thermal decomposition can proceed in two steps: ring opening and N2 separation. The activation energies of the two steps are 152.3kJ/mol and 44.67kJ/mol respectively. The ring opening is the rate-controlling step.     

Structural Characteristics and Decomposition Mechanism of 2, 2＂-Dimethyl-5, 5＇-Azotetrazole

The geometry and the potential curve of thermal decomposition for 2, 2＇ dimethyl-5, 5＇-azotetraol （2-DMAT） are calculated by ab initio quantum chemistry method. The structural characteristics and decomposition mechanism are carefully studied. It is found that the terrazzo ring satisfies 4n ＋ 2 rule and it is a conjugated π-systems for 2 DMAT, The azotetrazol has aromaic characteristic and its thermal decomposition can proceed in two steps： ring opening and N2 separation, The activation energies of the two steps are 152.3 kJ/mol and 44.67 kJ/mol respectively. The ring opening is the rate-controlling step.     

1,1′-DM-5,5′-AT和2,2′-DM-5,5′-AT热分解机理的量子化学研究

采用量子化学从头算方法全优化计算了1,1′-二甲基-5,5′-偶氮四唑(1,1′-DM-5,5′-AT)和2,2′-二甲基-5,5′-偶氮四唑(2,2′-DM-5,5′-AT)热分解反应位能曲线,探讨了它们的热分解机理.研究发现热分解按开环和脱氮两步完成,推测的机理可由取代四唑的热分解实验和理论研究所支持.计算得到1,1′-DM-5,5′-AT两步反应的活化能分别为243.5、64.01 kJ/mol;2,2′-DM-5,5′-AT两步反应的活化能分别为152.3、44.67 kJ/mol. 二者的热分解活化能都表明开环反应是速度控制步骤.前者的两步反应的活化能均大于后者的活化能.从动力学性质显示前者比后者有更好的稳定性.     

1，1＇-DM-5，5＇-AT和2，2＇-DM-5，5＇-AT热分解机理的量子化学研究

采用量子化学从头算方法全优化计算了1，1＇-二甲基-5，5’-偶氮四唑（1，1＇-DM-5，5’-AT）和2，2’-二甲基-5，5’-偶氮四唑（2，2’-DM-5，5’-AT）热分解反应位能曲线，探讨了它们的热分解机理。研究发现热分解按开环和脱氮两步完成，推测的机理可由取代四唑的热分解实验和理论研究所支持。计算得到1，1’-DM-5，5’-AT两步反应的活化能分别为243．5、64．01kJ／mol；2，2’-DM-5，5’-AT两步反应的活化能分别为152．3、44．67kJ／mol,二者的热分解活化能都表明开环反应是速度控制步骤。前者的两步反应的活化能均大于后者的活化能。从动力学性质显示前者比后者有更好的稳定性。     

均四嗪热分解机理的从头算分子动力学模拟及密度泛涵理论研究

运用从头算分子动力学(AIMD)方法对均四嗪分子的热分解轨迹进行了模拟,用密度泛涵理论在B3LYP/6-311G(d,p)水平下计算了极小点和过渡态的几何结构和能量性质。然后在多种理论水平下(包括B3LYP/6-311 G(2df,2p)、G3MP2B3、G3B3、CCSD(T)/6-311G(d,p)、CCSD(T)/6-311 G(2df,2p))计算了反应物、产物和过渡态的单点能,并运用微正则变分过渡态理论(μVT)计算了均四嗪的热分解反应速率常数,得到较为准确可靠的反应信息。研究结果表明:均四嗪分子的热分解机理为协同的三键断裂,生成1个N2和2个HCN,此机理与均四嗪的光分解机理一致。     

［Mg(H2O)6］(NTO)2·2H2O的热分解机理及量子化学研究（英）

用碱式碳酸镁与3-硝基-1,2,4-三唑-5-酮(NTO)在水中合成了[Mg(H2O)6](NTO)2·2H2O.用DSC,TG/DTG和IR研究了它的热分解机理.以晶体实验构型为初始值对配合物用6-31 G基组在B3LYP水平下进行量子化学计算.结果表明Mg原子与配位水分子之间的配位键具有共价键性质.NTO环上的成环氮原子都带负电荷,而硝基上(-NO2)的氮原子带有正电荷,说明标题配合物在加热至一定温度时,-NO2将首先离去,这与热分解实验结果一致.