对一些叠氮化合物的叠氮自由基键离解能的计算

用4个高精度的完全基组CBS(CBS-Q,CBS-QB3,CBS-Lq和CBS-4M),B3LYP/6-311G,B3LYP/6-311 G和MP2配合6-311G与6-31 G等多个不同大小的基组的计算方法,对HN3、CH3N3、C2H5N3、NCN3、C2H3N3和NH2CH2N3中离解掉叠氮自由基(·N3)时的键离解能进行计算.将计算的键离解能与实验值进行比较,发现B3LYP和4种完全基组计算方法都不能为这些叠氮化合物计算出满意的键离解能,而MP2方法,尤其配合6-31 G基组时,能够计算出与实验值吻合得很好的R—N3键离解能.因此,当计算这些中小型叠氮化合物中离解掉叠氮基的键离解能时,用MP2/6-31 G是一种可靠的计算方法.

The Calculation of Bond Dissociation Energies for Azide Group in Some Azido Compounds

Bond dissociation energies (BDEs) for removal of the azide group in HN3, CH3N3, C2H5N3, NCN3, C2H3N3 and NH2CH2N3 are calculated by the four different highly accurate complete basis sets (CBS-Q, CBS-QB3, CBS-Lq and CBS-4M), B3LYP with 6-311G** and 6-311 G** basis sets, and MP2 with 6-311G** and 6-311 G** etc.By comparing the computed energies and experimental results, it is found that both B3LYP and all four complete basis set (CBS) methods are unable to predict the satisfactory results of bond dissociation energy, however, the bond dissociation energies computed at MP2 method are in better agreement with the experimental values for these azido compounds, especially with 6-31 G** basis set.Therefore, for small- and medium-sized molecular system of azido compounds with removing azide groups, MP2/6-31 G** method well be a reliable method to calculate the BDEs.