A theoretical exploration of new species on the 1[H, Se, I] potential energy surface: Energetics, structures, IR spectra, and heats of formation

Abstract

New molecular species HSeI, HISe, and SeI were investigated theoretically for the first time at a high level of theory, CCSD(T). Computations were carried out with the series of correlation consistent basis sets (aug-cc-pVnZ-PP) and the results extrapolated to the complete basis set limit. Accounting for core-valence correlation into the wavefunction, and of anharmonic effects on the vibrational frequencies were also explored, making the results of structural, energetic, and vibrational properties a very reliable source of data for these yet unknown species. HSeI, viewed as normal covalently bonded species, turned out to be more stable by 42.04 kcal mol−1 than HISe. Bonding between I and Se in HISe can be rationalized as resulting from an electron pair donation from I to Se, the classical dative bond. These two species are separated by a barrier (ΔG#) of 52.35 kcal mol−1. Corrections arising from spin-orbit and scalar relativistic effects were also considered in the evaluation of atomization energies. For SeI, we estimate ΔfH values of 36.87 and 35.16 kcal mol−1 at 0 K and 298.15 K; for HSeI, we had 18.25 and 16.72 kcal mol−1, respectively.