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

Abstract

Twenty 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.

Perspectives in the Synergetic Photothermocatalysis of Hydrogen Sulfide Decomposition for Hydrogen Production: A Comprehensive Review

“…H 2 S, with a bond length of about 2.8 Å, compared with H 2 O with a bond length of about 1.0 Å exhibits weaker bonding since its atoms are further apart and can break down into its constituents even at low temperatures. 15 This means that a variety of processes, such as simple heating, irradiation, electrolysis, photolysis, etc., can release H 2 from H 2 S. Moreover, there is scope for H 2 S as a viable raw source of H 2 because H 2 S splitting requires a lower energy (ΔG°= 33.44 kJ/mol) compared to that of water splitting (ΔG°= 237.17 kJ/mol). Sulfur (S 2 ) is also a beneficial byproduct that can be produced when H 2 S is converted to H 2 .…”