The 5515 $\overset{\circ}{\mathrm A}$ Electronic Transition and the Geometric Structure of s-Tetrazine

摘要: The electronic absorption spectrum of gaseous s-tetrazine (H$\_2$C$\_2$N$\_4$) in the visible region has been examined under high resolution, and rotational analyses J-structure have performed for bands six isotopic species. results permitted determination molecular structure s-tetrazine, both $^1$A$\_g$ ground state A$^1$B$_{3u}$ excited state. molecule its is not as distorted from hexagonal conformation previous X-ray data suggest: principal parameters are $\widehat{\mathrm{NCN}} = 124^\circ\cdot6; \quad r(\mathrm{C-N}) 1\cdot338 \overset{\circ}{\mathrm A}; r(\mathrm{N-N}) 1\cdot330 r(\mathrm{C-H}) 1\cdot07 \pm 0\cdot02 A}.$ On excitation N-N bond lengths reduced by 0$\cdot$11 $\overset{\circ}{\mathrm A}$ separation carbon atoms increases 0$\cdot$10 A}$. It does seem possible to understand considerable change geometry on basis simple Huckel $\pi$-electron theory.