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Reaction-Partner-Dependent Switching between Single-Valley and Bifurcating Reactivity in 3-Azacyclopentadienone
Rama Krishna Kadiyam1, Priyanshu Kaneri1, Ravinder Pawar1
1Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal506004, Telangana, India.
The Journal of Physical Chemistry. A
|July 18, 2026
Summary
Reaction partner identity dictates 3-azacyclopentadienone cycloaddition dynamics, switching between single-valley descent, ambimodal branching, and post-transition-state bifurcation pathways.
Area of Science:
- * Organic Chemistry
- * Theoretical Chemistry
- * Computational Chemistry
Background:
- * The cycloaddition behavior of 3-azacyclopentadienone is highly dependent on the reaction partner.
- * Understanding how this dependence influences post-transition-state dynamics is crucial.
Purpose of the Study:
- * To investigate the endo cycloadditions of 3-azacyclopentadienone with furan and cyclopentadiene.
- * To elucidate the impact of reaction partner identity on post-transition-state dynamics.
Main Methods:
- * Density Functional Theory (DFT) calculations.
- * DLPNO-CCSD(T) single-point energy calculations.
- * Quasi-classical molecular dynamics (MD) simulations.
- * Intrinsic bond orbital (IBO) and electron density analyses.
- * Solvation Model Density (SMD) calculations.
Main Results:
- * Reaction partner identity significantly alters both transition-state regions and downstream reaction landscapes.
- * The furan system exhibits a highly asynchronous ambimodal transition structure with a dynamic preference for one product, while the competing pathway follows a single-valley route.
- * Cyclopentadiene reactions show bifurcating post-transition-state surfaces with substantial two-product dynamic competition.
- * Solvation effects in various solvents (dichloromethane, THF, acetonitrile) minimally impact barrier heights and kinetic ordering.
Conclusions:
- * Reaction partner identity is a key determinant in controlling the complex dynamics of 3-azacyclopentadienone cycloadditions.
- * The study reveals distinct dynamic behaviors, including single-valley descent, biased ambimodal branching, and persistent post-transition-state bifurcation.
- * Computational methods provide deep insights into the intricate bond reorganization and electron delocalization governing these reactions.
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