Basis Set Superposition Error Effects Cause the Apparent Nonexistence of the Ethene/Benzenium Ion Complex on the MP2 Potential Energy Surface

In a recent Letter (J. Phys. Chem. A 2008, 112, 6399) Kolboe and Svelle reported that the ethene/benzenium ion complex found by B3LYP transforms into an ethylbenzenium ion when MP2 with a large basis set is used. We find that the failure of MP2 to locate the ethene/benzenium ion complex is due to large basis set superposition errors.