Computational studies of carbodiimide rings

Area of Science:

• Computational Chemistry
• Organic Chemistry
• Theoretical Chemistry

Background:

• Alicyclic carbodiimides are cyclic organic compounds with the general formula RN═C═NR.
• Understanding their isomeric structures and transition states is crucial for predicting reactivity and stability.

Purpose of the Study:

• To computationally investigate the transition states between alicyclic carbodiimide isomers.
• To analyze the structural, symmetry, and stereochemical properties of these transition states.

Main Methods:

• Ab initio calculations using the MP2/6-31G(d,p) level of theory.
• Intrinsic Reaction Coordinate (IRC) analyses and energy minimization.
• Molecular mechanics and molecular dynamics simulations for specific ring sizes.

Main Results:

• Transition states were identified for alicyclic carbodiimides with rings six through twelve.
• The dihedral angle and symmetry point groups of transition states vary with ring size (even vs. odd).
• Antisymmetric pathways yield enantiomeric pairs, while symmetric pathways produce diastereomeric isomers.

Conclusions:

• The five-membered ring carbodiimide is predicted to be a stable, isolable structure.
• The study discusses the potential for optical resolution of the seven-membered ring carbodiimide.
• Computational methods successfully mapped pathways and isomers for alicyclic carbodiimides.