Kazan Department of Joint Supercomputer Center of Russian Academy of Sciences-Branch of Federal Scientific Center "Scientific Research Institute for System Analysis of the RAS", Lobachevskii Street 2/31, 420111 Kazan, Russia.
Analytical Chemistry, Certification and Quality Management Department, Kazan National Research Technological University, K. Marx Street 68, 420015 Kazan, Russia.
Int J Mol Sci. 2021 Nov 8;22(21):12067. doi: 10.3390/ijms222112067.
Quantum-chemical calculation of most important parameters of molecular and electronic structures of octa-carbon C having cubic form (bond lengths, bond and torsion angles) using CCSD(T)/QZVP and DFT B3PW91/QZVP methods, has been carried out. NBO analysis data and HOMO/LUMO images for this compound are presented, too. Good agreement was found between the structural data obtained using the above two quantum-chemical methods and, also, with corresponding experimental data. Also, the standard thermodynamic parameters of formation of cubic C considered here, and namely standard enthalpy Δ(298K), entropy S(298K) and Gibbs' energy Δ(298K) of formation for this compound were calculated. By using this data, a theoretically possible variant of the synthesis of this compound by dehydrogenation of cubane CH is considered, and the thermodynamic characteristics of each of the four stages of this process have been calculated. It is noted that each of the four stages of this process is characterized by a very high (about 500 kJ/mol) enthalpy of activation, as a result of that, for their realization within a sufficiently short time, the use of appropriate catalysts is necessary.
使用 CCSD(T)/QZVP 和 DFT B3PW91/QZVP 方法，对具有立方形式的八碳 C（键长、键和扭转角）的分子和电子结构的最重要参数进行了量子化学计算。还给出了该化合物的 NBO 分析数据和 HOMO/LUMO 图像。发现使用上述两种量子化学方法获得的结构数据与相应的实验数据之间存在良好的一致性。此外，还计算了这里考虑的立方 C 的标准生成热力学参数，即该化合物的标准焓变Δ(298K)、熵 S(298K)和吉布斯自由能Δ(298K)生成。利用这些数据，考虑了通过脱氢立方烷 CH 合成这种化合物的理论上可能的方案，并计算了该过程四个阶段中每一个阶段的热力学特性。需要注意的是，该过程的四个阶段中的每一个阶段都具有非常高的（约 500 kJ/mol）活化焓，因此，为了在足够短的时间内实现它们，需要使用适当的催化剂。
