Splitting of Hydrogen Sulfide by Group 14 Elements (Si, Ge, Sn, Pb) in Excess Argon at Cryogenic Temperatures

Abstract

The water gas reaction C + HO → CO + H has been employed for centuries; however little is known for analogous reaction M + HS → MS + H (M = Si, Ge, Sn, Pb). In addition, this latter reaction is intriguing in its function of converting pollutant HS to clean energy source H. We report herein the reactions of laser-ablated Group 14 atom M (M = Si, Ge, Sn, Pb) with HS using matrix isolation infrared spectroscopy as well as the state-of-the-art quantum chemical calculations. Important reactive intermediates HMSH with high active H (protonic H and hydridic H) are identified. In addition, the reaction mechanisms are established for insertion reaction M + HS → HMSH, and photoinduced H elimination reactions of HMSH → MS+ H and HSiS → SiS+ H in low-temperature matrices.

Nonadiabatic reaction dynamics to silicon monosulfide (SiS): A key molecular building block to sulfur-rich interstellar grains

“…Owing to the repulsion of the Si-D and S-D sigma bonds, cis-S2 is destabilized by 11 kJ mol −1 with respect to trans-S2. The relative stabilities of these isomers are in good agreement with previous results of 10 to 11 kJ mol −1 (cis-S2 versus trans-S2) and 39 to 45 kJ mol −1 (trans-S2 versus S3) (59)(60)(61). Three intermediates (cis-S2, trans-S2, and S3) may undergo a barrierless atomic deuterium loss to the D1-thiosilaformyl radical (DSiS; X 2 A′, p3) via simple bond rupture processes; both cis-S2 and S3 can emit molecular deuterium via tight transition states located 157 and 43 kJ mol −1 below the energy of the separated reactants leading to silicon monosulfide (SiS; X 1  + ).…”

Hydrogenation of CO2 Promoted by Silicon-Activated H2S: Origin and Implications

“…Although this optimal path is slightly exothermic (0.2 kcal•mol −1 ), it should be mentioned that this energy does not include the silicon incorporation step. In fact, the insertion of an Si atom into the S-H bond of H 2 S is spontaneous and highly exothermic (66.2 kcal•mol −1 at the CCSD(T)/6-311++g(3df,3pd)//B3LYP/6-311++g(3df,3pd) level) as proved in a previous study [20].…”

“…So, how to ensure this when H 2 S is employed as a potential hydrogen source? In a recent matrix isolation study [20], it was found that Si atoms can react spontaneously with H 2 S to produce a HSiSH molecule that is stable until exposure to UV radiation. If the two hydrogens (from HSiSH) are active toward CO x hydrogenation, SiS, a very stable molecule with Si=S multiple bonds [21][22][23], will be one of the final products, which suggests little chance for the production of COS, and hence contributes to the target reaction.…”