四乙酰基二硝基六氮杂异伍兹烷分子结构研究

四乙酰基二硝基六氮杂异伍兹烷(TADNIW)是合成六硝基六氮杂异伍兹烷(HNIW)的中间体。该文用Gaussian 98软件包,采用密度泛函理论B3LYP和标准基组6-31G对所选构型进行了全优化计算,在结构上对TADNIW的键长、键角、二面角、Mu lliken电荷及集居数进行了理论分析,发现笼形化合物的六元环成船式构象,硝基处于桥头,骨架以亚稳态存在。结构分析表明,六元环上N—NO2键相对较稳定,采用一般的硝解条件反应不能进行,作者提出了新的反应机理,即水解-硝化假设:含有酰胺基团的一类化合物在含水的硝化介质中首先发生水解生成相应的仲胺,碱性较强的仲胺再在氮硝化催化剂的作用下,迅速硝化成硝胺。计算得到TADNIW分子总能量为-1 583.375 682 a.u.,前线轨道能量差ΔE(ELUMO-EHOMO)为4.123 eV。计算IR谱图与实验IR谱图对比,误差小于20 cm-1。

Theoretical Study of the Structure of TADNIW

Tetraacetyl-dinitro-hexaazaisowurtzitane(TADNIW) is an intermediate in the preparation of hexanitrohexaazaisowartzitane(HNIW).In this article,Gaussian 98 software package is used.At the level of B3LYP/6-31G,the structure of TADNIW is optimized,and the analysis of the structure of TADNIW,such as bond length,bond angle,dihedral angle,Mulliken charge and population,is available to the reaction characters of the caged compound.The six-membered ring of the caged compound presents a ship-like conformation and the nitryl is on the bridge head.The framework is in the sub-steady state.Judging from the structure analysis,the bond N—NO_2 is comparatively steady,but the reaction cannot carry out with conventional nitrating agent.Therefore new understanding of reaction mechanism is coming into being.The hypothesis of hydrolyzation-nitration is put forward,that compounds containing acylamide group are hydrolyzed into secondary amines firstly in the nitrating agent containing water,and then nitrated rapidly into nitro compounds with the help of N-nitration catalyst.This conforms well with the experiments.The total energy of TADNIW is(-1 583.375 682) a.u.and the difference of the energies of frontier molecular orbitals is 4.123 eV.The calculated IR spectrum is compared with the experimental IR spectrum,and the error is less than 20 cm~(-1).