Tian Han-Rui, Chen Miao-Miao, Wang Kai, Chen Zuo-Chang, Fu Chao-Yong, Zhang Qianyan, Li Shu-Hui, Deng Shun-Liu, Yao Yang-Rong, Xie Su-Yuan, Huang Rong-Bin, Zheng Lan-Sun
State Key Lab for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , China.
J Am Chem Soc. 2019 Apr 24;141(16):6651-6657. doi: 10.1021/jacs.9b01638. Epub 2019 Mar 26.
The combustion has long been applied for industrial synthesis of carbon materials such as fullerenes as well as carbon particles (known as carbon black), but the components and structures of the carbon soot are far from being clarified. Herein, we retrieve an unprecedented hydrofullerene CH from a soot of a low-pressure combustion of benzene-acetylene-oxygen. Unambiguously characterized by single-crystal X-ray diffraction, the CH renders a nonclassical geometry incorporating two heptagons and two pairs of fused pentagons in a C symmetry. The common vertexes of the fused pentagons are bonded with four hydrogen atoms to convert the hydrogen-linking carbon atoms from sp to sp hybridization, which together with the adjacent heptagons essentially releases the sp-bond strains on the abutting-pentagon sites of the diheptagonal fused pentagon C (dihept-C). DFT computations suggest the possibility for an in situ hydrogenation process leading to stabilization of the dihept-C. In addition, the experiments have been carried out to study heptagon-dependent properties of dihept-CH, indicating the key responsibility of the heptagon for changing hydrocarbon activity and electronic properties. The present work with the unprecedented double-heptagon-containing hydrofullerene successfully isolated and identified as one of the low-pressure combustion products shows that the heptagon is a new building block for constructing fullerene products in addition to pentagons and hexagons in low-pressure combustion systems.
燃烧长期以来一直应用于富勒烯等碳材料以及碳颗粒（即炭黑）的工业合成，但碳烟的成分和结构远未得到阐明。在此，我们从苯 - 乙炔 - 氧气低压燃烧产生的碳烟中提取出了一种前所未有的氢化富勒烯CH。通过单晶X射线衍射明确表征，CH呈现出一种非经典几何结构，在C对称性中包含两个七边形和两对稠合五边形。稠合五边形的公共顶点与四个氢原子相连，使氢连接的碳原子从sp杂化转变为sp杂化，这与相邻的七边形一起基本上释放了二角形稠合五边形C（dihept - C）邻接五边形位点上的sp键应变。密度泛函理论计算表明存在原位氢化过程导致dihept - C稳定的可能性。此外，已经开展实验研究dihept - CH的七边形依赖性性质，表明七边形对改变烃类活性和电子性质起着关键作用。这项成功分离并鉴定出前所未有的含双七边形氢化富勒烯作为低压燃烧产物之一的工作表明，在低压燃烧系统中，除了五边形和六边形外，七边形是构建富勒烯产物的一种新的结构单元。
