The N4 molecule has an open‐chain triplet C2h structure

The lowest‐energy N4 is computed ab initio to be the planar C2h(3Bu) open‐chain structure 13. The open‐chain N4 singlet‐state structures dissociate on geometry optimization. The tetraazatetrahedrane Td structure 1 and the tetrazete D2h structure 2 are minima at MP2/6‐31G*. However, both are higher in energy than 13 (24.1 and 21.2 Kcal/mol [UQCISD) (T)(full)/6‐311+G*//MP2/6‐31G* + ZPE(MP2/6‐31G)*, respectively]. The energy of 13 is 157.5 kcal/mol higher than that of two N2(1∑ molecules [UQCISD(T)(Full)/6‐311+G*//MP2/6‐31G*]