H＋NF_2→NF（α）＋HF反应的从头算研究  

Ab Initio study of H+HF2→NF(α)+HF Reaction

作　　者：郭敬忠[1] 邓从豪[1] 

机构地区：[1]山东大学理论化学研究室

出　　处：《高等学校化学学报》1996年第12期1904-1908,共5页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金

摘　　要：本文用量子化学从头算法对Ｈ＋ＮＦ_２→ＮＦ（α）＋ＨＦ反应进行了理论研究，采用ＭＰ_２（ＦＵＬＬ）／６－３１Ｇ（ｄ）方法计算了反应物、产物、中间体和过渡态的构型参数和振动频率，然后用Ｇａｕｓｓｉａｎ－２理论计算了各物种的精确能量，计算结果表明：反应在单重态势能面上进行，电子激发态ＮＦ（α）通过复合－消除机理产生，用Ｇ２理论计算２９８Ｋ下反应的焓变为－１１９．４ｋＪ／ｍｏｌ，过渡态比反应物能量低９８．４ｋＪ／ｍｏｌ．中间体ＨＮＦ２是势能面的最低点，比反应物的能量低３１３．５ｋＪ／ｍｏｌ．The reaction of H+NF_2→NF(α)+HF was studied by using ab initio methods.The geometries and frequencies for all species were calculated at MP2(FULL) / 6-31G(d)level of theory.The energies of all species were further calculated using Gaussian 2 theory.The result implies that the reaction proceeds via an addition-elimination mechanism on the lowest singlet potential surface.The addition processes form HNF2 molecules as the intermediates without barriers,The metastable radical NF(α)is formed by unimolecular HF elimination reactions via three-centered transition state.The best estimation of the heat of reaction is -119.4kJ/mol at 298 K. The energy of the transition state forming NF(α) is 98.4 kJ/mol lower than the reactants,The intermediate HNF_2 with an energy of 313.5kJ/mol lower than the reactants is the lowest point on the potential surface,Since the overall activation energy is negative,the title reaction is expected to be a good chemical source of NF(α)radical which was found experimentally.

关 键 词：从头算法 反应机理 G2理论 NF 自由基 

分 类 号：O621.146[理学—有机化学]