DFT insights into the basicity of some cyclic allenes.

The proton affinity (PA) and gas phase basicity values of previously reported cyclic allene series are investigated using high-level quantum chemical calculations. Some of the studied structures possessed more than one protonation site. All protonation types were explored for each structure and the compounds with PA value more than ≈1030 kJ mol−1 were considered superbasic structures. Cyclic allene's basicity strength was affected by ring size, adjacent heteroatom's presence and resonance existence in protonated form. [ABSTRACT FROM AUTHOR]