源自经典N-杂环卡宾的凯库勒双自由基类似物。
Kekulé diradicaloids derived from a classical N-heterocyclic carbene.
作者信息
Rottschäfer Dennis, Neumann Beate, Stammler Hans-Georg, Andrada Diego M, Ghadwal Rajendra S
机构信息
Anorganische Molekülchemie und Katalyse , Lehrstuhl für Anorganische Chemie und Strukturchemie , Centrum für Molekulare Materialien , Fakultät für Chemie , Universität Bielefeld , Universitätsstr. 25 , D-33615 Bielefeld , Germany . Email:
Allgemeine und Anorganische Chemie , Universität des Saarlandes , Campus C4.1 , D-66123 Saarbrücken , Germany.
出版信息
Chem Sci. 2018 Apr 24;9(22):4970-4976. doi: 10.1039/c8sc01209a. eCollection 2018 Jun 14.
The direct double carbenylation of 1,4-diiodobenzene and 4,4'-dibromobiphenyl with a classical N-heterocyclic carbene, SIPr () (SIPr = :C{(2,6-iPrCH)}CHCH), by means of nickel catalysis gives rise to 1,3-imidazolinium salts (SIPr)(CH)(SIPr) () and (SIPr)(CH)(SIPr) () as off-white solids. Two-electron reduction of and with KC cleanly yields Kekulé diradicaloid compounds [(SIPr)(CH)(SIPr)] () and [(SIPr)(CH)(SIPr)] (), respectively, as crystalline solids. Structural parameters and DFT as well as CASSCF calculations suggest the closed-shell singlet ground state for and . Calculations reveal a very low singlet-triplet energy gap Δ for (10.7 kcal mol), while Δ for (29.1 kcal mol) is rather large.
通过镍催化，使1,4 - 二碘苯和4,4'-二溴联苯与经典的N - 杂环卡宾SIPr（SIPr = :C{(2,6 - iPr₂C₆H₃)}CHCH）直接进行双羰基化反应，生成灰白色固体的1,3 - 咪唑鎓盐(SIPr)(CH)(SIPr) ()和(SIPr)(CH)(SIPr) ()。用KC对 和 进行双电子还原，分别得到结晶固体的凯库勒双自由基化合物[(SIPr)(CH)(SIPr)] ()和[(SIPr)(CH)(SIPr)] ()。结构参数、密度泛函理论（DFT）以及完全活性空间自洽场（CASSCF）计算表明， 和 具有闭壳层单重态基态。计算结果显示， 的单重态 - 三重态能隙Δ非常小（10.7 kcal mol），而 的Δ（29.1 kcal mol）相当大。
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