Novel halogenated cyclopentasilylene‐2,4‐dienes via DFT

Abstract

AbstractIn view of immense importance of silylenes and the fact that their properties undergo significant changes on substitution with halogens, here, we have used B3LYP/6‐311++G** level of theory to access the effects of 1–4 halogens (X = F, Cl, Br, and I) on four unprecedented sets of cyclopentasilylene‐2,4‐dienes; with the following formulas: SiC4H3X (1 X), SiC4H2X2 (2 X), SiC4HX3 (3 X), and SiC4X4 (4 X). In going down from F to I, the singlet (s)‐triplet (t) energy gap (ΔEs‐t, a possible indication of stability), and band gap (ΔEH‐L) decrease while nucleophilicity (N), chemical potential (μ), and proton affinity (PA) increase. The overall order of N, μ, and PA for each X is 2 X > 1 X > 3 X > 4 X. Precedence of 2 X over 1 X is attributed to the symmetric cross conjugation in the former. The highest and lowest N are shown by 2 I and 4 F. The trend of divalent angle () for each X is 4 X > 1 X > 3 X > 2 X. The results show that in going from electron withdrawing groups (EWGs) to electron donating groups (EDGs), the ΔEs‐t and ΔEH‐L decrease while N, μ, and PA increase. Also, rather high N of our scrutinized silylenes may suggest new promising ligands in organometallic chemistry.