title: σ Aromaticity Dominates in the Unsaturated Three-Membered Ring of Cyclopropametallapentalenes from Groups 7-9: A DFT Study.
abstract: Aromaticity, an old but still fantastic topic, has long attracted considerable interest of chemists. Generally, π aromaticity is described by π-electron delocalization in closed circuits of unsaturated compounds whereas σ-electron delocalization in saturated rings leads to σ aromaticity. Interestingly, our recent study shows that σ aromaticity can be dominating in an unsaturated three-membered ring (3MR) of cyclopropaosmapentalene. An interesting question is raised: Can the σ aromaticity, which is dominant in the unsaturated 3MR, be extended to other cyclopropametallapentalenes? If so, how could the metal centers, ligands, and substituents affect the σ aromaticity? Here, we report a thorough theoretical study on these issues. The nucleus-independent chemical shift calculations and the anisotropy of the current-induced density plots reveal the dominant σ aromaticity in these unsaturated 3MRs. In addition, our calculations show that substituents on the 3MRs have significant effects on the σ aromaticity, whereas the ligand effect is particularly small.
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (P. R. China) http://junzhu.chem8.org.
authors.forename: Yulei
authors.initials: Y
authors.lastname: Hao
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (P. R. China) http://junzhu.chem8.org.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (P. R. China) http://junzhu.chem8.org. jun.zhu@xmu.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
keywords: aromaticity; density functional calculations; metallaaromatics; unsaturated compounds