Superbasicity of 1,3,5-cycloheptatriene derivatives and their proton sponges in gas phase

A new class of superbases was designed using cycloheptatriene derivatives and their basicities were assessed theoretically by B3LYP/6-311++G(d, p) method in gas phase. The superbasicity of these compounds is due to formation of an aromatic 7-membered ring upon protonation which stabilizes the protonated structure. Other fragments such as guanidine and phosphazene groups were also added to these compounds to enhance their basicities. The computed proton affinities (PA) for these superbases were 245-288 kcal/mol. Cycloheptatriene was also used in the design of some proton sponges to increase their basicities. The computed PAs of the proton sponges were 256-279 kcal/mol. (C) 2017 Elsevier B.V. All rights reserved.