理论研究F2BN3多聚体的结构特色和热力学稳定性

在密度泛函理论（DFT）B3LYP/6-311+G*水平上计算研究了叠氮二氟硼多聚体(F2BN3)n (n=1-4)，获得了它们的结构和热力学性质，讨论了几何参数随聚合度的变化趋势。多聚体(F2BN3)2-4的优化构型均为由不同子体系的叠氮基α−N和B原子相连形成的环状结构。三聚体的船扭式构象比椅式构象的结合能低10.54 kJ•mol-1；四个新获得的四聚体的结合能差异较大，大小为3.1~45.65 kJ•mol-1。由焓变可知，单体形成二聚体在热力学上是不利的，而形成三聚体和四聚体在高达1200 K的温度下是有利的，同时分析比较了后续反应的热力学参数。

Theoretical Studies on Structural Feature and Thermodynamic Stability of F2BN3 Oligomers

Density functional theory (DFT) was employed to study on (F2BN3)n (n=1～4) clusters at the B3LYP/6-311+G* level. A set of the structural and thermodynamic properties have been obtained. Trends in structural parameters with oligomerization degree n are discussed. The optimized clusters (F2BN3)2-4 all possess cyclic structure formed by B atoms bridged by the α-nitrogen of the azide groups. The boat-twisting conformation lies 10.54 kJ*mol-1 lower in binding energies than the chair isomer for the trimers. The four tetramers newly gained show greatly binding energy differences in range of 3.1～45.65 kJ*mol-1. The dimerization is thermodynamically unfavorable by the enthalpy. However, the formations of trimers and tetramers are very favorable thermodynamically even at high (1200 K) temperatures. Comparisons of the thermodynamic parameters of subsequent oligomerization are also given.