Thiaphosphiranes and Their Complexes: Systematic Study on Ring Strain and Ring Cleavage Reactions

Area of Science:

• Computational Chemistry
• Organometallic Chemistry
• Reaction Mechanisms

Background:

• Thiaphosphirane derivatives are strained heterocyclic compounds.
• Understanding their reactivity is crucial for synthetic applications.
• Complexation with metal carbonyls and boranes can alter their electronic and structural properties.

Purpose of the Study:

• To computationally investigate the energies and geometries of thiaphosphirane derivatives and their W(CO)5 and BH3 complexes.
• To analyze the ring-opening reactions and associated bond strengths.
• To elucidate the factors influencing the stability and reactivity of these complexes.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Analysis of structural parameters (bond distances, force constants).
• Application of Bader's theory of atoms-in-molecules and bond order calculations.

Main Results:

• Ring strain is influenced by substituents and complexation, with W(CO)5 and BH3 complexes exhibiting increased strain.
• Substituents significantly affect relative energies of ring-opening products and transition states.
• κP-complexes are generally more stable than κS-complexes, and haptotropic shifts show distinct preferences for P-C versus C-S bond cleavage.

Conclusions:

• Computational insights into thiaphosphirane reactivity and stability.
• Demonstration of how complexation and substituents modulate ring strain and reaction pathways.
• Identification of novel reaction pathways, including peribicyclic reactions.