Exploring new molecular species on the 1[H, Se, F] singlet potential energy surface: Energetics, structures, IR spectra, and heats of formation

Structural, energetic, and vibrational properties of new molecular species, HSeF and HFSe, the associated transition state, and dissociation fragments are investigated using a state-of-the-art theoretical approach, CCSD(T)/CBS. HSeF is a normal covalently bonded molecule 38.98 kcal mol−1 more stable than the complex HF−Se, which shows an unusual structure with a central fluorine atom and a bond angle of 101.8°. A barrier (ΔG#) of 49.01 kcal mol−1 separates the two species. Vibrational frequencies are also quite distinct. Heats of formation are evaluated for the diatomic fragments and HSeF. Final ΔfH values depend on the experimental accuracy of those of Se(g) and H2Se.