A REKS assessment of the face-diagonal bond in 1,3-didehydrocubane and a comparison with benzyne biradicals
A REKS assessment of the face-diagonal bond in 1,3-didehydrocubane and a comparison with benzyne biradicals
复制标题
DOI：
10.1002/ejoc.200300201
复制
发表时间：
2003-10-31
影响因子：
2.8
通讯作者：
Shaik, S
中科院分区：
文献类型：
--
作者：
de Visser, SP;Filatov, M;Shaik, S
在 B3LYP/6-31G(d) 理论水平上，使用自旋限制系综参考 Kohn-Sham (REKS) 密度泛函计算研究了三种异构立方烷双自由基。最稳定的双自由基是邻立方烯，间立方烯和对立方烯双自由基的能量分别高出4.7 kcal mol(-1) 和17.8 kcal mol(-1)。单重态基态与其最低的三重态完全分开。这些单重态-三重态能量差异主要源自邻位和间位异构体的空间相互作用，而对位异构体的这些相互作用相当弱。与对苯炔相比，对苯炔也被考虑与不饱和体系进行比较，对古巴二基中的单重态-三重态能隙仍然很大，这主要是由于其更强的键合相互作用。 （(C) Wiley-VCH Verlag GmbH & Co. KGaA，69451 Weinheim，德国，2003 年）。
The three isomeric cubane biradicals were studied using spin-restricted ensemble-referenced Kohn-Sham (REKS) density functional calculations at the B3LYP/6-31G(d) level of theory. The most stable biradical was found to be ortho-cubene with the meta-cubene and para-cubene biradicals 4.7 kcal mol(-1) and 17.8 kcal mol(-1) higher in energy, respectively. The singlet ground states are well separated from their lowest lying triplet states. These singlet-triplet energy differences mostly originate from through-space interactions for the ortho and meta isomers, whereas these interactions are rather weak for the para isomer. In contrast to para-benzyne, which was also considered for comparison with an unsaturated system, the singlet-triplet energy gap remains large in para-cubadiyl, mainly as a result of its much stronger through-bond interactions. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).