A study into the possible homoaromatic nature of some related carbene and cationic intermediates with the potential for transannular interaction

A comparison of the aromatic nature of the cations and carbenes centered at the 8-position of tricyclo[3.2.1.0(2,4)] octane, the 9-position of pentacyclo[4.3.0.0(2,4).0(3,8).0(5,7)]nonane, the 6-position of tricyclo-[3.1. 1.0(2,4)]heptane, and the 4-position of tetracyclo[3.3.0.0(2,8).0(3,6)]octane has been undertaken. Hybrid density functional theory calculations have been used to examine the geometric, energetic, and magnetic characteristics of each cation, singlet carbene, and triplet carbene. The results shed light on the flexibility of the polycycles to achieve stable intermediates and on the breadth of homoaromaticity.