Theoretical study of OCCHCN as a potential alternative insulation gas for SF₆

Cyanoketene (OCCHCN) has been reported as a potential alternative insulation gas for SF₆ in Patent US0135817. Stationary point equilibrium geometries on the ground state have been optimized at the B3LYP/6-311+G(d,p) level, and the harmonic vibration frequencies are calculated at the same level. The HOMO-LUMO energy gaps (E_g), ionization potentials (IP), and electron affinities (EA) of the studied molecules are obtained. The minimum energy path (MEP) is obtained by the intrinsic reaction coordinate (IRC) theory, and the energetic information is further refined by QCISD(T) (single-point) method. The results show that OCCHCN can be used as SF₆ alternative insulation gas in high voltage equipment according to potential energy surface analysis. As the isomerization and the cleavage reactions potential barriers are lower than the E_g and IP values, resulting in OCCHCN is not easy to be ionized and excited.