Two‐fold C−C cross‐coupling of N‐heterocyclic carbenes [NHCs; SIPr=C(NArCH₂)₂, 1; IPr=C(NArCH)₂, 2; Me‐IPr=C(NArCMe)₂, 3; Ar=2,6‐iPr₂C₆H₃] with 4,4′′‐diiodo‐p‐terphenyl under Ni catalysis furnished [(SIPr)(C₆H₄)₃(SIPr)](I)₂ (4), [(IPr)(C₆H₄)₃(IPr)](I)₂ (5), and [(Me‐IPr)(C₆H₄)₃(Me‐IPr)](I)₂ (6). Two‐electron reduction of 4–6 with KC₈ readily afforded NHC analogues of Müller's hydrocarbon (MH), [(SIPr)(C₆H₄)₃(SIPr)] (7), [(IPr)(C₆H₄)₃(IPr)] (8), and [(Me‐IPr)(C₆H₄)₃(Me‐IPr)] (9), respectively, as highly colored crystalline solids. Quantum chemical calculations suggested that the singlet ground state for 7–9 possesses a vertical singlet–triplet energy gap ΔE_S‐T of −7.24 to −7.60 kcal mol⁻¹, which is significantly lower compared to that of the NHC analogues of Thiele's (TH) and Chichibabin's (CH) (18–38 kcal mol⁻¹) hydrocarbons. Importantly, the calculated diradical character (y) of 7–9 (y≈0.6) is considerably higher compared to that of the related TH and CH (y=0.1–0.4), suggesting the open‐shell singlet character of 7–9.

中文翻译：

---

通过间距增强双基性：Müller烃的N-杂环碳类似物

N-杂环卡宾[NHCs]的两倍CC交叉偶联。SIPR = C（NArCH ₂）₂，1 ; IPR = C（NArCH）₂，2 ; ME-IPR = C（NArCMe）₂，3 ; 在Ni催化下，Ar = _2,6 - i Pr ₂ C ₆ H ₃ ]与4,4'-二碘对苯并三苯基提供[（SIPr）（C ₆ H ₄）₃（SIPr）]（I）₂（4），[（IPr）（C ₆ H ₄）₃（IPr）]（I）₂（5）和[（Me-IPr）（C₆ H ₄）₃（Me-IPr）] [I）₂（6）。用KC ₈将4 – 6进行两电子还原，很容易得到Müller烃（MH），[（SIPr）（C ₆ H ₄）₃（SIPr）]（7），[（IPr）（C ₆ H ₄）₃（IPr）]（8）和[（Me-IPr）（C ₆ H ₄）₃（Me-IPr）]（9）分别为高度着色的结晶固体。量子化学计算表明，单重态的基态为7 – 9的垂直单重态-三重态能隙ΔE _S-T为-7.24至-7.60 kcal mol ^-1，比Thiele（TH）和Chichibabin（CH）的NHC类似物要低得多（18 –38 kcal mol ^-1）碳氢化合物。重要的是，所计算出的二价基团字符（ÿ的）7 - 9（Ý ≈0.6）是相当高的相比，相关的TH和CH（的Ý = 0.1-0.4），表明的开壳层单字符7 - 9。