Chemical structure stabilities of a SixFy (x ≤ 6, y ≤ 12) series

Abstract

In this paper, we construct a Si_xF_y (x ≤ 6, y ≤ 12) series optimised at the B3LYP/6-31G(d,p) level. At the same level, we perform frontline molecular orbital (FMO), Mayer bond order (MBO), molecular surface electrostatic potential (MS-EPS) and natural population analysis (NPA) calculations to study the chemical structure stabilities of these Si_xF_y molecules. The FMO and MBO results demonstrate that the chemical structure stabilities of the Si_xF_y (x ≤ 6, y ≤ 12) series are ranked (from strong to weak) as SiF₄ > Si₂F₆ > Si₃F₈ > Si₄F₁₀ > SiF₂ > Si₅F₁₂ > Si₃F₆ (ring) > Si₅F₁₀ (ring) > Si₆F₁₂ (ring) > Si₄F₈ (ring). Furthermore, the chemical structure stabilities of the chains are stronger than those of the rings, while the number of silicon atoms is the same. In addition, infrared spectroscopy analysis shows that SiF₄ is the most stable among the Si_xF_y (x ≤ 6, y ≤ 12) series, followed by Si₂F₆, and SiF₂ is unstable. The experimental results are consistent with theoretical calculations. Finally, the MS-EPS and NPA results indicate that compounds in the Si_xF_y (x ≤ 6, y ≤ 12) series tend to be attacked by nucleophiles rather than by electrophiles; also, they show poor chemical structure stability when encountering nucleophiles.