DFT Studies on Structures, Stabilities, and Electron Affinities of closo-Supercarboranes C2Bn鈥?Hn (n = 13鈥?0)

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• 作者：Jiji Zhang ; Zhenyang Lin ; Zuowei Xie
• 刊名：Organometallics
• 出版年：2015
• 出版时间：December 14, 2015
• 年：2015
• 卷：34
• 期：23
• 页码：5576-5588
• 全文大小：1174K
• ISSN：1520-6041

文摘

Structures, stabilities, and electron affinities of closo-supercarboranes C₂B_n鈥?H_n (n = 13鈥?0) were studied with the aid of DFT calculations. The results regarding the relative stability of positional isomers for each closo-supercarborane can be well understood with the qualitative rules established on the basis of early studies on 5- to 12-vertex carboranes C₂B_n鈥?H_n (n = 5鈥?2). The calculated cumulative BH addition energies for the most stable CAd (CAd = carbon-atoms-adjacent) and CAp (CAp = carbon-atoms-apart) positional isomers (using the equation 1,2-C₂B₁₀H₁₂ + (n 鈥?12) BH_inc 鈫?C₂B_n鈥?H_n (n = 13鈥?0), where BH_inc is set as the energy difference between B₆H₁₀ and B₅H₉) suggest that the thermodynamic stability should not be the reason for nonobservation of 15-vertex CAp closo-carborane and other larger closo-supercarboranes C₂B_n鈥?H_n (n = 16鈥?0), and effort toward their synthesis is worth spending. The calculated HOMO鈥揕UMO energy gaps show the relatively low chemical stability of 15-vertex closo-carboranes, explaining the difficulty of their experimental synthesis. Among these closo-supercarboranes studied, the 17-vertex carborane is predicted to be the most stable one, thus the most plausible target for experimental synthesis.