Theoretical determination of a reaction intermediate: Fukui function analysis, dual reactivity descriptor and activation energy

•The highlights of this paper consist in the theoretical approach to the chemistry of complex heterocyclic systems that shows to be in good agreement with experimental findings. Thus it lets clear that computational modellation of phosphorus heterocycles based on fukui functions and dual reactivity descriptors serves as a valuable instrument to predict shape and reactivity even of complex systems. Furthermore an approach to explain and predict negative values for fukui functions based on intuitive chemical properties is undertaken.•To the best of our knowledge this is the first time that a computational approach is successfully used on complex polycyclic phosphorus heterocycles.