High basicity of alkylated 2-tetrazenes: an ab initio study

The spatial and electronic structure of the parent 2-tetrazene and its tetramethyl- and ethyl derivatives are examined by an ab initio approach. It is shown by using the MP2(fc)/6-311+G∗∗//HF/6-31G∗+ZPVE(HF/6-32G∗) model that alkylated tetrazenes exhibit strong intrinsic basicity as evidenced by their high absolute proton affinities. The latter is due to the appreciable electron density concentration at the terminal nitrogen atoms, the increased II-electron delocalization in conjugate acids and the electron density relaxation effect occurring upon protonation.