THEORETICAL SEARCH FOR LARGE RYDBERG MOLECULES - NH3CH3, NH2(CH3)2, NH(CH3)3, AND N(CH3)4

On the basis of ab initio calculations, four new large metastable Rydberg molecules: NH3CH3, NH2(CH3)2, NH(CH3)3, and N(CH3)4 are predicted to exist. All of these neutral species possess high-symmetry local minima but are not thermodynamically stable with respect to loss of H or CH3. Because they have pronounced barriers on the dissociation pathways, they should be metastable. The dissociation barriers for NHn(CH3)4-n decomposing to NHn-1(CH3)4-n+H are smaller than for dissociation into NHn(CH3)4-n-1+CH3. Thus, the lifetime of N(CH3)4 should be much longer than that of NH4 due to the larger dissociation barrier and the heavier mass of the departing CH3 species.