Insights into reaction mechanisms of phosphenium cation and methyleneimine: a theoretical study

Abstract

The mechanism of cycloaddition reaction between phosphenium cation and phosphindene with methyleneimine has been systematically investigated at the B3LYP/6-311++G(d,p) level of theory in order to better understand the reactivity for the valence isoelectronic of carbene. Phosphenium cation acts as an electrophilic reagent and accepts σ electrons of methyleneimine to form a complex in the first addition step. The greater the positive charge at phosphorus atom in phosphenium cation, the more stable the formed complex is. Introduction of substituents will decrease positive charge on phosphorus atom in phosphenium cation. The order of positive charge on phosphorus atom is HP⁺-F > HP⁺-OH > HP⁺-NH₂, which is consistent with their Lewis acidities. The complex transforms to a three-membered ring product via a transition state in the second cyclization step. The product is less stable than the complex due to its tension of small ring.

Graphical Abstract

Keywords:

• Phosphenium cation
• phosphindene
• reaction mechanism
• cycloaddition reaction

Disclosure Statement

No potential conflict of interest was reported by the author.

Additional information

Funding

This work was supported by the Nature Science Foundation of Shandong Province (ZR2020MC004), Focus on Research and Development Plan in Shandong Province (2019JZZY011116), the Science and Technology Project of University of Jinan (XKY2030), and the Project of Research Leader Studio of University Funding 20 items in Jinan (2019GXRC058).