Roles of H2O in comparison with H2S in the complexes of thioaldehydes and hydrogen chalcogenides

Abstract

AbstractTwenty stable geometrical structures of the interactions between RCHS and nH2Z (R = H, F, Cl, Br, CH3; n = 1‐2; Z = O, S) were investigated. Addition of H2O or H2S molecule into the RCHS∙∙∙1H2Z system induces an enhancement of the stability and cooperative capacity of the complexes investigated, in which it is ca. 2 times more stable for adding H2O compared to H2S. The substitution of one H atom in HCHS by both halogen (F, Cl, Br) and CH3 group causes an increase in the larger stability of RCHS∙∙∙H2Z in comparison with HCHS∙∙∙H2Z. The stability of complexes follows the order of H < F ~ Cl ~ Br < CH3 substituted‐derivatives. Strength of hydrogen bonds decreases in the sequence of O–H∙∙∙O > O–H∙∙∙S > S–H∙∙∙S > Csp2–H∙∙∙O > Csp2–H∙∙∙S. Besides, the O/S–H∙∙∙S and O–H∙∙∙O red‐shifting hydrogen bonds are mainly governed by an increase in the population of the σ*(Csp2−H) and σ*(O/S−H) orbitals. Meanwhile, the Csp2–H blue shift in Csp2–H∙∙∙O/S hydrogen bonds are determined by both the decrease in the electron density of the σ*(Csp2−H) orbitals and the lowering in s‐character percentage of Csp2 in Csp2‐H bonds.