Knowledge Bank

Ab initio configuration interaction calculations using minimal and double-zeta basis sets have been performed on the $\mathrm{<mrow\; data-mjx-texclass="ORD">1,3</mrow>}n\Pi \ast$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}n$ cation states of sym-tetrazine. The interaction of the four nitrogen nonbonding orbitals and the resulting degree of localization (or symmetry breaking) is investigated. The interactions are discussed in terms of through-space and through-bond interactions. The results are compared to previous calculations on $pyrazine1$. The potential surface of the excited $\mathrm{<mrow\; data-mjx-texclass="ORD">1,3</mrow>}B3u(n\Pi \ast )$ states have been probed with the PRDDO method. The results shed light on the initial phases of the dissociation of sym-tetrazine into $2HCN+N2$.