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| How long a C–C bond can be? An example of extraordinary long C-C single bond in 1,2-diarylamino-o-carborane |
| Yile Wu, Jie Zhang, Zuowei Xie |
| Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Hong Kong, China |
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| Guide The longest C-C single bond of 1.990(4) Å known thus far is observed in the single crystal X-ray structure of 1,2-(NHMes)2-o-carborane (Mes = 2,4,6-trimethylphenyl), which is readily synthesized via a one-pot process. |
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Abstract How long a C-C bond can be? A question has long fascinated chemists. This work reports an example of extraordinary long C-C bond distance of 1.990(4) Å observed in single-crystal X-ray structure of 1,2-(NHMes)2-o-carborane (2; Mes=2,4,6-trimethylphenyl). DFT calculations show that hyperconjugation of lone pairs of the nitrogen atoms into the empty σ* orbital of the cage C-C bond is the origin of the bond elongation. Such hyperconjugation can be suppressed if the two nitrogen atoms in 2 are linked to a Lewis acidic germanium (Ⅱ) center.
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Received: 15 February 2019
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| Fund:This work was supported by a grant from the Research Grants Council of the Hong Kong Special Administration Region (No. 14305918). |
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Corresponding Authors:
Zuowei Xie
E-mail: zxie@cuhk.edu.hk
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