Theoretical study of geometry and nucleophilicity of the exocyclic methylene in five-membered ring cyclic ketene acetals, neutral and protonated, containing pnictogen and chalcogen heteroatoms

详细信息    查看全文

• 作者：Adam E. Catoire (1)
  Debbie J. Beard (1)
  Svein Saebo (1)
  
• 关键词：MP2 ; Proton affinities ; Nucleophilicity ; Cyclic ketene acetals
• 刊名：Structural Chemistry
• 出版年：2014
• 出版时间：February 2014
• 年：2014
• 卷：25
• 期：1
• 页码：371-376
• 全文大小：286 KB
• 作者单位：Adam E. Catoire (1)
  Debbie J. Beard (1)
  Svein Saebo (1)
  
  1. Department of Chemistry, Mississippi State University, P.O. Box 9573, Mississippi State, MS, 3975, USA
  
• ISSN：1572-9001

文摘

A series of neutral and protonated five-membered ring cyclic ketene acetals have been examined computationally for any trends in nucleophilicity in the exocyclic methylene and for their ground state geometries. A total of 58 different species were examined, 29 neutral molecules and the corresponding 29 protonated species. The heteroatoms that were used in the heterocyclic ring were a combination of nitrogen, phosphorus, and arsenic from the pnictogen family and oxygen, sulfur, and selenium from the chalcogen family. All geometries were initially optimized at using density functional theory and all stationary points were confirmed to be either minima or transition states through vibrational analysis. All the geometries were consequentially optimized using M?ller–Plesset second order perturbation theory with a polarized triple zeta basis set. The main focus of the study was the nucleophilicity of the exocyclic methylene carbon atom and its dependence on heteroatom substitution. As probes for nucleophilicity, the proton affinities of the neutral species, the bond lengths of the exocyclic double bond, and atomic charges were used. The study also resulted in some interesting molecular geometries.