RDX和HMX的二氟氨基衍生物结构与性能的密度泛函理论研究

DFT Study on the Structures and Properties of Difluoramino Derivatives of RDX and HMX

应用密度泛函理论(DFT)B3LYP/6-31G^**方法对设计的RDX和HMX的—NF2衍生物进行了理论研究;设计等键反应并根据Hess定律预测了固态生成焓;应用Politzer校正方法计算了密度ρ;由K-J方程估算了爆热(Q)、爆速(D)和爆压(p),讨论了—NF2对HOF、ρ、Q、D和p的影响;由键离解能(BDE)和撞击感度(H50)评价了化合物的稳定性,并探讨了可能的热分解引发机理。结果表明,—NF2取代会降低生成焓;化合物的密度范围为1.96~2.34g/cm^3,均高于RDX和HMX的密度;所有衍生物的D均在8.85~9.98km/s,p均在35.07~50.99GPa范围,绝大部分化合物的D和p优于RDX和HMX,—NF2对D和p的贡献较大;所有化合物的BDE均在90~160kJ/mol,均满足高能材料稳定性的要求,预测的H50值的大小顺序基本上与BDE结果相一致,化合物中引入更多的—NF2通常会降低其稳定性。因此,大多数RDX和HMX的—NF2衍生物具有很好的爆轰性能与稳定性,为潜在的高能量密度材料。

The -NF 2 substitution derivatives of RDX and HMX were studied at the B3LYP/6-31G^** level of density functional theory.The condensed-phase heats of formation(HOF) were predicted with isodesmic reactions and Hess law.The density (ρ) was calculated by the Politzer method.The heat of explosion( Q ), detonation velocity ( D ), and detonation pressure ( p ) were estimated by the K-J equation.The effects of -NF 2 on HOF,ρ, Q, D, and p were discussed.The stability of compounds was evaluated using bond dissociation energies (BDE) and impact sensitivities ( H 50 ).The possible initiation mechanism of thermal decomposition was discussed.The results show that -NF 2 substitution can reduce the heats of formation.The ρ of the compounds ranges from 1.96 to 2.34 g/cm 3, which is higher than that of RDX and HMX.The D of all derivatives is 8.85- 9.98 km/s, and the p is in the range of 35.07-50.99 GPa.Most compounds have better D and p than RDX and HMX, and -NF 2 contributes a lot to D and p .The BDE of all compounds is in the range of 90-160 kJ/mol, which meets the requirements of high-energy material stability.The sequence of the predicted H 50 values is basically consistent with the BDE results .The introduction of more -NF 2 groups in the compounds usually reduces the stability.Therefore, most of the -NF 2 derivatives of RDX and HMX have good detonation performance and stability and can be promising candidates of high energy density compounds.