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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Exploration of C_6H_6 Potential Energy Surface:A Computational Effort to Unravel the Relative Stabilities and Synthetic Feasibility of New Benzene Isomers
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Exploration of C_6H_6 Potential Energy Surface:A Computational Effort to Unravel the Relative Stabilities and Synthetic Feasibility of New Benzene Isomers

机译：C_6H_6势能面的探索：为阐明新的苯异构体的相对稳定性和合成可行性而进行的计算

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Ab initio(MP2,CCSD(T))and hybrid density functional theory(B3LYP)calculations with up to triple-zeta basis set were done to locate all possible minima,where each carbon in the molecule is tetracoordinate,on the C_6H_6 potential energy surface.The search was initiated with a total of 218 structures,and in few cases,geometrical and stereoisomers were considered.The exhaustive study on all these topological structures resulted in a total of 263 stationary points on the C_6H_6 potential energy surface.The B3LYP level characterizes 209 as minima,31 as transition states,8 as second-order,7 as third-order,and 1 as fourth-order saddle points.The remaining 7 structures could be located as stationary points only at the MP2 level.The molecules were classified into acyclic,monocyclic,bicyclic,tricyclic,and tetracyclic.The acyclic isomers fall within a range of 60-80 kcal/mol higher in energy compared to benzene.Among the cyclic structures,the range of relative stabilities of minima is larger,viz.,monocyclic(31-146 kcal/mol),bicyclic(72-159 kcal/mol),tricyclic(72-300 kcal/mol),and tetracyclic(102-156 kcal/mol).Strain due to small three and four membered rings and constrained double and triple bonds control the relative stabilities of these isomers.The computed isomers exhibit various novel bonding modes for carbon,namely,planar tetracoordinate,hypervalent,pyramidal,bent/ twisted double bonds,vicinal dicarbenes,nonlinear triple bonds,and so forth.Absolute chemical hardness values have no correlation with the relative stabilities,and about 45 molecules have higher hardness values than that of benzene.
机译：进行了从头算（MP2，CCSD（T））和杂化密度泛函理论（B3LYP）的计算，直到三重Zeta基集，以将所有可能的最小值定位在C_6H_6势能面上，其中分子中的每个碳原子都是四配位的搜索开始时共有218个结构，在少数情况下考虑了几何异构体和立体异构体。对所有这些拓扑结构的详尽研究导致C_6H_6势能表面上共有263个固定点.B3LYP能级最小值为209，过渡态为31，二阶为8，三阶为7，四阶鞍点为1。其余7个结构仅在MP2水平上可以定位为固定点。无环异构体的能量范围比苯高60-80 kcal / mol。在环状结构中，最小相对稳定性的范围较大，即。 ，单环（31-146 kcal / mol），双环（72-159 kcal / mol），三环（72-300 kcal / mol）和四环（102-156 kcal / mol）。三元环和四元环的小应变计算的异构体表现出各种新颖的碳键模式，即平面四配位，高价，金字塔形，弯曲/扭曲双键，邻二碳烯，非线性三键等。化学绝对值与相对稳定性无关，约45个分子的硬度值比苯高。

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