Sun Yu-Wang, Wang Hai-Yan, Ding Yi-Hong
Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University Changchun 130023 P. R. China
College of Computer Science and Technology, Changchun University Changchun 130023 P. R. China.
RSC Adv. 2019 Dec 9;9(69):40772-40780. doi: 10.1039/c9ra08943h. eCollection 2019 Dec 3.
Metal cyanide/isocyanide and hydrometal cyanide/isocyanide compounds are key metal-carriers in interstellar space. Lighter group 14 elements (X = C/Si/Ge) cyanides/isocyanides and hydrocyanides/hydroisocyanides have been studied theoretically and experimentally. However, no reports are available on the analogues of tin (Sn) and lead (Pb). In this work, we carried out the first theoretical study on the structures and stabilities of [X,C,N] and [H,X,C,N] (X = Sn/Pb) at the CCSD(T)/def2-QZVPP//B3LYP/def2-QZVPP level. Comparisons were made with the lower analogues (X = C/Si/Ge) concerning the structural, energetic and bonding properties. Significantly different from that of c-CN, a dative-bonded valence structure of c-XCN for heavier X was revealed for the first time, which can account for the rather worse kinetic stability of cyclic [X,C,N] for heavier X = Si/Ge. A unique kind of agostic bonding was found within three isomers of [H,Pb,C,N], whereas it is absent for X = C/Si/Ge/Sn. The computed structural and spectroscopic data could aid future laboratory and astrophysical detection of the [X,C,N] and [H,X,C,N] (X = Sn/Pb) isomers.
金属氰化物/异氰化物和氢金属氰化物/异氰化物化合物是星际空间中的关键金属载体。较轻的第14族元素（X = C/Si/Ge）的氰化物/异氰化物以及氢氰化物/氢异氰化物已在理论和实验上进行了研究。然而，关于锡（Sn）和铅（Pb）的类似物尚无相关报道。在这项工作中，我们首次在CCSD(T)/def2-QZVPP//B3LYP/def2-QZVPP水平上对[X,C,N]和[H,X,C,N]（X = Sn/Pb）的结构和稳定性进行了理论研究。并与较轻的类似物（X = C/Si/Ge）在结构、能量和键合性质方面进行了比较。首次揭示了对于较重的X，c-XCN的配位键合价结构与c-CN的显著不同，这可以解释对于较重的X = Si/Ge，环状[X,C,N]的动力学稳定性较差的原因。在[H,Pb,C,N]的三种异构体中发现了一种独特的agostic键，而对于X = C/Si/Ge/Sn则不存在。计算得到的结构和光谱数据有助于未来在实验室和天体物理中对[X,C,N]和[H,X,C,N]（X = Sn/Pb）异构体进行检测。
