热平衡的、垂直扭曲的烯烃三重态自由基。
A Thermally Populated, Perpendicularly Twisted Alkene Triplet Diradical.
机构信息
School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.
Anorganisch-Chemisches Institut and IWR, Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
出版信息
Angew Chem Int Ed Engl. 2016 Nov 14;55(47):14600-14605. doi: 10.1002/anie.201607415. Epub 2016 Oct 20.
Variable-temperature NMR and ESR spectroscopic studies reveal that bis(dibenzo[a,i]fluorenylidene) 1 possesses a singlet ground state, 1(S ), while the 90° twisted triplet 1(T ) is populated to a small extent already at room temperature. Analysis of the increasing amount of paramagnetic 1(T ) at temperatures between 300 and 500 K yields the exchange interaction J /h c=3351 cm and a singlet-triplet energy splitting of 9.6 kcal mol , which is in excellent agreement with calculations (9.3 kcal mol at the UKS BP86/B3LYP/revPBE level of theory). In contrast, the zero-field splitting parameter D is very small (calculated value -0.018 cm ) and unmeasurable.
变温 NMR 和 ESR 光谱研究表明，双（二苯并[a，i]芴基）1 具有单线态基态 1(S)，而 90°扭曲三重态 1(T) 已经在室温下以较小的程度存在。在 300 至 500 K 之间的温度下，对顺磁 1(T) 含量的增加进行分析，得出交换相互作用 J / hc=3351 cm 和单线态-三重态能分裂为 9.6 kcal/mol，这与计算结果（UK S BP86/B3LYP/revPBE 理论水平的 9.3 kcal/mol）非常吻合。相比之下，零场分裂参数 D 非常小（计算值-0.018 cm）且无法测量。
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