氮氟化合物生成焓的理论预测
左怀远;孔璐璐;俞帅;刘恩良;杜洪臣
【摘 要】利用原子化反应法和生成反应法在 G3、G3X （X＝B3，MP2，MP2B3）、B3LYP/CC-PVTZ 和 CBS-4M 水平下对 NF3、NF5、NFO、NFO2、NF3 O、N2 F2、N2 F4、N3 F、NF3 BF3、NFOBF3、NFO2 BF3和 NF3 OBF3的生成焓进行了量子化学计算，在 G3水平下计算了这些物质的热力学性质。结果表明，G3方法结合生成反应法能准确预测此类物质的生成焓，热力学性质计算值与实验值均非常接近，证明 G3方法适用于计算此类物质的热力学性质。%The heats of formation of NF3 ,NF5 ,NFO,NFO2 ,NF3 O,N2 F2 ,N2 F4 ,N3 F,NF3 BF3 ,NFOBF3 ,NFO2 BF3 and NF3 OBF3 were calculated using atomization reaction (AR),formation reaction (FR)at the G3,G3 (X)(X = B3,MP2 and MP2B3),B3LYP/CC-PVTZ and CBS-4M levels,and the thermodynamic functions of these compounds were calculated under G3 level.Results show that FR in conjunction with the G3 theory can accurately evaluate the heats of formation of these compounds. The results agree well with the experimental data,showing that G3 is suitable for calculating the thermodynamic functions of these compounds.
【期刊名称】《火学报》
【年(卷),期】2014(000)004
【总页数】5页(P30-34)
react to中文
【关键词】物理化学;量子化学;氮氟化物;密度泛函理论;完全基组;生成焓
【作 者】左怀远;孔璐璐;俞帅;刘恩良;杜洪臣
【作者单位】浙江农林大学理学院，浙江省林业生物质化学利用重点实验室，浙江 杭州 311300;浙江农林大学工程学院，浙江 杭州 311300;浙江农林大学工程学院，浙江 杭州 311300;内蒙动力机械研究所，内蒙古 呼和浩特 010010;浙江农林大学理学院，浙江省林业生物质化学利用重点实验室，浙江 杭州 311300
【正文语种】中 文
【中图分类】TJ55;O645
Inorganic compounds containing N-F bonds are important in technological applications，among these compounds，nitrogen trifluoride（NF3），tetrafluorohydrazine（N2F4），difluoramine（NF2H），nitrosyl fluoride（NOF），nitryl fluoride（NO2F），and trifluoroamine oxide（NF3O）are the common known compounds.Although the nitrogen fluorides have been known for hundreds of years［1-6］，the chemical properties of these compounds have not been studied in detail.For a long time after their discovery，they remained only academic curiosities.It was not until the potential of these compounds as rocket propellants had been recognized at about 1960 that a systematic study of the oxyfluorides was initiated.The study of liquid and solid rocket propellants has stimulated widespread interest in compounds containing N-F bonds.The reasons for this interest are as follows：First，the N-F bond is of low energy and easily broken；secondly，nitrogen fluorine compounds provide an alternative source of fluorine［7］.
Nitrogen fluorine compounds exhibit strong oxidizing properties.Certain nitrogen fluorine compounds react with organic compounds to form numerous organic substances containing the－NF2or－NONF groups.One characteristic feature of nitrogen fluorine comp
ounds is that，they can form adducts with strong Lewis acids［8］（i.e.BF3，Br F3，AsF5，Sb F5）.
Since these compounds possess high energies，this type of substance are widely used in explosive industry.Compared with their structures，the studies on their thermodynamic properties are scarce，it is necessary to study thermodynamic properties，i.e.heat of formation（HOF）.
As is known，with the development of computer technology and quantum chemistry methods，theoretical prediction of thermodynamic properties has become a realistic tool and has arisen a lot of interest［9-12］.In 2012，DU［13］et al calculated the chlorine fluorides heat of formation using Gaussian-3（G3）methods，the results showed that the G3 theory are better than the G3X theories.
In this study，the heats of formation of nitrogen fluorides（NF3，NF5，NFO，NFO2，NF3O，N2F2，N2F4，N3F）were calculated using the atomization reaction and formation reaction under theG3，G3B3，G3MP2，G3MP2B3，CBS-4M，and B3LYP／CC-PVTZ le
vels.In order to check the accuracy of the calculated results，the calculated values were then compared with the experimental values［14］.The heats of formation of the adducts NF3BF3，NFO BF3，NFO2BF3and NF3O BF3were estimated using formation reaction（abbreviated as FR）method.
The title compounds are optimized at the above methods and the harmonic vibrational frequencies and corresponding zero point vibrational energies were calculated in all of the optimized geometries，and real frequencies were obtained in all of the cases with Gaussian 03 program［15］.
In the formation reactions（e.g.0.5N2＋1.5F2＝NF3），N2，O2，or F2are designated as the reactants，and the atomization reaction（AR，e.g.NF3＝N＋3F）are employed to derive the heat of formation of the title compounds according to the Hess law.
For the formation reactions，the heat of reactionat 298 K can be calculated from the following equation（1）：
Whereandare the sum of the heats of formation of the reactants and the products at 298 K，respectively；ΔE0is the change in total energy between the products and the reactants at 0 K；ΔEZPEis the difference between the zero-point energy（ZPE）of the products and the reactants；ΔH0T is the thermal correction from 0 to 298 K；ΔnRT is the work term，since the experimental heat of formation of the reactants（N2，F2and O2）are aero，the heats of formation of the title compounds can be obtained with the calculated
For the atomic reactions（abbreviated as AR），i e，NF3＝N＋ 3F，the heat of reactionat 298 K can also be calculated from the equation（1）：
The experimental heat of formation of the atom N，F and O are 472.68，79.38 and 249.18 kJ·mol－1，respectively［16］.The heat of formation of the title compounds can be estimated using the experimental heat of formation of the atoms and the heat of reaction of equation（1）.

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