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<p>In this study, the [2 + 2] cycloaddition reaction between ethylene <b>1</b> and ketene <b>2</b>, along with its chalcogen-substituted derivatives <b>3</b>–<b>5</b>, leading to the formation of four-membered rings, was investigated within the framework of Molecular Electron Density Theory (MEDT) at the B3LYP-D3/6–311 + + G(d,p) level of theory. The dimerization of ethylene exhibits a high activation Gibbs free energy (ΔG<sup>≠</sup> = 88.0&#xa0;kcal&#xa0;mol<sup>−1</sup>), reflecting the nonpolar nature of this reaction, which follows a one-step asynchronous mechanism. The incorporation of chalcogen atoms into the ethylene framework leads to a moderate reduction in activation energy, following the trend ketene (<b>2</b>, X = O) &gt; thioketene (<b>3</b>, X = S) &gt; selenoketene (<b>4</b>, X = Se) &gt; telluroketene (<b>5</b>, X = Te). This decrease in activation energy is accompanied by an increase in the reaction’s polarity, as evidenced by the electrophilicity difference between the reactants and the Global Electron Density Transfer (GEDT) at the transition state. Furthermore, the Bonding Evolution Theory (BET) analysis reveals that the introduction of chalcogen atoms alters the reaction mechanism, shifting from a one-step synchronous to a one-step asynchronous pathway. In this revised mechanism, the C–C bond directly attached to the chalcogen atom forms first, underscoring the significant influence of chalcogen substitution on the electronic and structural evolution of the reaction.</p>

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Mechanistic study of the [2 + 2] cycloaddition of ethylene with ketene derivatives via MEDT

  • 期刊论文

  • 发表日期：

    2025年5月27日

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  • Mohamed Chellegui,
  • Ines Salhi,
  • Ali Ben Ahmed,
  • Sofiane Benmetir,
  • Raad Nasrullah Salih,
  • Haydar A. Mohammad-Salim,
  • Jesus Vicente de Julián-Ortiz

摘要

In this study, the [2 + 2] cycloaddition reaction between ethylene 1 and ketene 2, along with its chalcogen-substituted derivatives 3–5, leading to the formation of four-membered rings, was investigated within the framework of Molecular Electron Density Theory (MEDT) at the B3LYP-D3/6–311 + + G(d,p) level of theory. The dimerization of ethylene exhibits a high activation Gibbs free energy (ΔG≠ = 88.0 kcal mol−1), reflecting the nonpolar nature of this reaction, which follows a one-step asynchronous mechanism. The incorporation of chalcogen atoms into the ethylene framework leads to a moderate reduction in activation energy, following the trend ketene (2, X = O) > thioketene (3, X = S) > selenoketene (4, X = Se) > telluroketene (5, X = Te). This decrease in activation energy is accompanied by an increase in the reaction’s polarity, as evidenced by the electrophilicity difference between the reactants and the Global Electron Density Transfer (GEDT) at the transition state. Furthermore, the Bonding Evolution Theory (BET) analysis reveals that the introduction of chalcogen atoms alters the reaction mechanism, shifting from a one-step synchronous to a one-step asynchronous pathway. In this revised mechanism, the C–C bond directly attached to the chalcogen atom forms first, underscoring the significant influence of chalcogen substitution on the electronic and structural evolution of the reaction.