Cyanoform and Its Isomers. Relative Stabilities, Spectroscopic Features, and Rearrangements by Coupled Cluster and MCSCF-Based Methods

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• 作者：Marek Szczepaniak ; Jerzy Moc
• 刊名：Journal of Physical Chemistry A
• 出版年：2017
• 出版时间：February 16, 2017
• 年：2017
• 卷：121
• 期：6
• 页码：1319-1327
• 全文大小：505K
• ISSN：1520-5215

文摘

Although an isolation of elusive tricyanomethane HC(CN)₃ was recently reported, the existence of other HC₄N₃ species has yet to be confirmed. In this work, the relative stabilities, spectroscopic features, and rearrangements of tricyanomethane and its four isomers are examined using single- (CCSD(T), CCSD(T)-F12) and multireference (MCSCF, MRPT2) methods. Tricyanomethane and dicyanoketenimine (NC)₂CCNH, which are found to be the two most stable HC₄N₃ isomers lying within 9 kcal/mol, can be discriminated by their spectroscopic parameters. The predicted stepwise interconversion path relating HC(CN)₃ and (NC)₂CCNH features the HC₄N₃ species comprising the C–C–N ring moiety, with the largest barrier being associated with the initial H migration to one of the CN carbons. Adding a water molecule reduces the H migration barrier strongly and makes it possible to interconvert tricyanomethane to dicyanoketenimine in a “concerted” way.