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五唑离子化合物是当前新型含能材料的一个研究热点，其制备通常以五唑共价化合物为前体实现。多数情况下，五唑共价化合物的稳定性对能否成功制备五唑离子化合物有很大影响。采用密度泛函理论B3LYP/6-31G**方法重点研究了18个直链取代五唑共价化合物（R—N5或N5—R—N5）的侧链化学键的解离能EBD和N5环的分解能垒Ea，分析了侧链对其稳定性和热解机理的影响。发现当R为羟基或氨基时，侧链容易断裂，N5环也容易破裂，难以得到N5-；当R为烷基时，N5环裂解的Ea相对较大，更可能得到N5-，且侧链C—N键和N5环的稳定性受烷基链长短影响不大；在双环分子中，两个N5环的裂解是先后发生的，后一个环的裂解能垒比前者高，裂解生成氮气和叠氮化物；分子侧链上的C—C键会先于C—N键断裂，从而可能使C—N键的EBD明显降低而对N5环的Ea影响不大，因此，在由五唑共价化合物制备五唑盐的过程中，先切断C—C键可能更利于得到N5-。“,”The study of polynitrogen pentazolate salts， which are usually achieved from the precursors of N5 covalent compounds， is the hotspot of research in the field of new energetic materials. In most cases， the stability of N5 covalent compounds will significantly affect the possibility of successful preparations of pentazolate salts. Herein， the calculations of dissociation energy （EBD） of the bonds in the straight side chain and activation energy （Ea） of the N5 ring were carried out for the selected eighteen non‑aryl substituted N5 compounds （R—N5 or N5—R—N5） by using the B3LYP/6-31G** method of density functional theory， and meanwhile the influence of the side chain on their stabilities and pyrolysis mechanism were investigated. When R is the hydroxyl or amino group， the side chain and the N5 ring are more prone to break， making it difficult to obtain the N5- ring. When R is alkyl， the Ea of the N5 ring cleavage is relatively larger， making it more likely to produce the N5- ring， and the stability of the side chain′s C—N bond as well as the N5 ring will be little affected by the length of the alkyl chain. The sequential cleavage of two N5 rings occurs in the bicyclic molecular structures and the energy barrier of the second ring is higher than that of the first one， resulting in the formation of N2 and azide. The C—C bond on the side chain of the molecule will be broken before the break of C—N bond， which may significantly reduce the EBD of the C—N bond but have little effect on the Ea of the N5 ring. Therefore， for the preparations of pentazolate salts from covalent pentazoles， cutting off the C—C bond first may be more conducive to obtaining N5- ring.