Reaction of Germylene with Sulfur Dioxide: Gas-Phase Kinetic and Theoretical Studies

Abstract

Time-resolved studies of germylene, GeH2, generated by laser flash photolysis of 3,4-dimethyl-1-germacyclopent-3-ene at 193 nm, have been carried out to obtain rate constants for its bimolecular reaction with SO2. The reaction was studied in the gas phase, mainly at a total pressure of 10 Torr (in SF6 bath gas) at five temperatures in the range 295–553 K. Pressure variation measurements over the range 1–100 Torr (SF6) at 295, 408, and 553 K revealed no pressure dependence. The second-order rate constants at 10 Torr (SF6 bath gas) fit the Arrhenius equation log(k/cm3 molecule–1 s–1) = (−11.01 ± 0.09) + (4.62 ± 0.65 kJ mol–1)/RT ln 10, where the uncertainties are single standard deviations. The collisional efficiency is 19% at 298 K, and in kinetic terms the reaction resembles that of SiH2 with SO2 quite closely. Quantum chemical calculations at the B3LYP/aug-cc-pvQZ level suggest a mechanism occurring via the initial addition of GeH2 to one O atom of SO2 to form H2GeOSO which, via a 1,3-H shift followed by a cyclization, leads to a four-membered-ring species, cyclo-HGeO2SH(cis)–. A low-energy H2 elimination results in the formation of cyclo-GeO2S, a hitherto unknown compound. A number of other species on the enthalpy surface have been identified, including the novel Ge(OH)2···S, a cyclic five-membered ring comprising an S atom stabilized by dihydroxygermylene. However, none of these other molecules seem to be involved as intermediates in this reaction, either because barriers to their formation or rearrangement are too high or because their enthalpies are insufficiently negative for them to be collisionally stabilized under experimental conditions. The reaction is compared and contrasted with that of SiH2 + SO2.

Molecular Main Group Metal Hydrides

“…The parent inorganic silylene SiH 2 is often touted as a key intermediate formed during the decomposition of SiH 4 into thin films of Si. , As shown in Scheme , SiH 2 can be generated as a transient species by the flash photolysis of PhSiH 3 , while photolysis of Me 2 SiH 2 and 1-chloro-1-silacyclopent-3-ene ( 738 ) yield MeSiH and ClSiH, respectively. , The reactivity of SiH 2 with small molecules, such as O 2 , H 2 O, HCl, CO 2 , MeC­(O)­H, Me 2 O, alkenes, , alkynes, N 2 (the H 2 Si·N 2 adduct is stable at 10 K), NO, or silanes (e.g., MeSiH 3 ), can lead to E–H bond insertion, oxidative addition, hydride migration, or Lewis acid–base adduct formation, depending on the nature of the substrate (Scheme ). Furthermore, SiH 2 also has been the subject of numerous computational investigations. − Laser flash photolysis of germacyclopentenes at 193 nm (Scheme ) yields GeH 2 , either in the gas phase or solution, , and reactivity paths that mirror those exhibited by SiH 2 with small molecules have been observed. − In related work, gas phase laser flash photolysis of 1,3,4-trimethyl­germacyclopent-3-ene ( 739 ) yields transient MeGeH (Scheme ), while passage of an electric discharge through H 3 GeCl vapor affords the reactive halogermylene HGeCl . The chemistry of SnH 2 is much less developed and access to this parent tetrelene is possible by passing an electric discharge through gaseous SnH 4 , which instigates H 2 loss .…”

Time‐resolved, Gas‐phase Kinetic and Quantum Chemical Studies of the Reaction of Germylene with Hydrogen Chloride

“…Less is known about the behaviour of GeH 2 and so we report further studies in the present paper. As well as our investigations [12–32] other kinetic studies have been undertaken by the group of King and Lawrance [33–35] in the gas phase and also by the group of Leigh [36] in the liquid phase, mainly of organogermylenes, GeR 2 (R=Me, Ph). A recent study by the group of Kaiser [37] has reported on the generation and gas phase behaviour of methylgermylene.…”

“…To put this study into perspective, the Arrhenius parameters obtained here are compared with those of other germylene reactions, [18,21,24,26,32] as well as those of silylene reactions with the same substrates [39,[46][47][48][49] in Table 4. Here it can be seen that this reaction possesses a similar small negative activation energy as other reactions of GeH 2 , typical of a reaction proceeding via an association complex.…”

Dithionite and sulfinate complexes from the reaction of SO2with decamethylsamarocene

“…[2][3][4][5] Besides the oxidation of sulfur dioxide to sulfur trioxide for the production of sulfuric acid, 6 the reduction of sulfur dioxide to elemental sulfur (Claus process) 7 or to sodium dithionite 8 are also well-established industrial processes. in main group chemistry the reduction of SO 2 with either [(THF)MgNPh] 6 20 or (SnNtBu) 4 , 21 and the reactions of SO 2 with germylene 22 and silylene in the gas phase have also been studied. With the exception of sodium dithionite 9,10 [ZnS 2 O 4 (pyridine)] n , 11 and [Sn 2 (S 2 O 4 ) 2 ], 12 only two families of structurally characterized dithionite transition metal complexes have been reported, namely [{Rh(C 5 H 4 R)} 2 (m-CH 2 ) 2 (m-O 2 SSO 2 )] (R = Me, Ph, Et, nPr, CH 2 Ph), [13][14][15][16][17][18] and [{(Z 5 -C 5 Me 5 )Mo(CO) 3 } 2 (S 2 O 4 )].…”

“…Today, there is growing interest in the reduction of SO 2 , e.g. in main group chemistry the reduction of SO 2 with either [(THF)MgNPh] 6 20 or (SnNtBu) 4 , 21 and the reactions of SO 2 with germylene 22 and silylene in the gas phase have also been studied. 23 Also the reduction of SO 2 with low valent nickel compounds resulting in a thiosulfate nickel(II) compound 24 and the activation of SO 2 by a Cr-Cr quintuple bond 25 have been reported recently.…”