How long a C–C bond can be? An example of extraordinary long C–C single bond in 1,2-diarylamino-o-carborane  

作　　者：Yile Wu Jie Zhang Zuowei Xie 

机构地区：[1]Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong

出　　处：《Chinese Chemical Letters》2019年第8期1530-1532,共3页中国化学快报（英文版）

基　　金：supported by a grant from the Research Grants Council of the Hong Kong Special Administration Region (No. 14305918)

摘　　要：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)?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 emptyσ^*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.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) ? 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.

关 键 词：O-CARBORANE C–C single BOND HYPERCONJUGATION AMINE X-ray structure 

分 类 号：O64[理学—物理化学]