A comparison of the reactivity of germylene and dimethylgermylene with some methylgermanes. Direct kinetic and quantum chemical studies

Becerra, Rosa; Боганов, С. Е.; Egorov, Mikhail P.; Faustov, V. I.; Krylova, I. V.; Нефедов, О. М.; Promyslov, V. M.; Walsh, Robin

doi:10.1039/b706148j

Cited by 20 publications

(46 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This parameter is in reasonable agreement with that used in several RRKM studies on the GeH 2 reactivity, in which it was adopted a temperature independent energy transfer parameter of 800 cm À1 . 53,54 Finally, despite the increase of the energy transfer parameter, our calculations still underpredict the GeH 2 decomposition rate by a factor of 1.6, well within the uncertainty range of these calculations, which have been estimated to be about a factor of 2 and 4 for the GeH 4 and GeH 2 decomposition reactions, respectively, due to the uncertainty of the calculated energies and transition state structures. Since in this case the validation of the computational results is based on the…”

Section: Discussionsupporting

confidence: 76%

Theoretical investigation of germane and germylene decomposition kinetics

Polino

Barbato

Cavallotti

2010

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The dissociation kinetics of germane and its decomposition products were studied determining microcanonical kinetic constants with RRKM theory and integrating the master equation using a stochastic approach. Relevant reaction parameters were calculated through first principles calculations. Structures of reactants and transition states were determined at the B3LYP/aug-cc-pvtz level while energies were computed at the CCSD(T) level and extended to the complete basis set limit. Though similar for many aspects to the kinetics of decomposition of SiH(4), GeH(4) has some peculiar features that indicate a different chemical reactivity. It was found that the main decomposition channel leads to the formation of germylene, GeH(2), which rapidly decomposes to atomic Ge and H(2). The dissociation of GeH(2) to Ge and H(2) is a formally spin forbidden reaction characterized by an activation energy of 160.3 kJ mol(-1) calculated at the minimum energy crossing point between the singlet and triplet states. The intersystem crossing probability was explicitly included in the microcanonical simulations through Landau-Zener theory. It was found that its effect on the reaction rate is almost negligible, both because of the large spin-orbit coupling between the singlet and triplet states and for the fall off conditions prevailing in the examined pressure and temperature ranges. Kinetic constants of the main decomposition channels were determined as a function of pressure and temperature between 0.0013 and 10 bar and 1100 and 1700 K. The high and low pressure kinetic constants for GeH(4) decomposition are 6.4 x 10(13) (T/K)(0.272) exp(-26 700 K/T) and 2.7 x 10(48) (T/K)(-9.05) exp(-31 600 K/T), while those for GeH(2) are 6.02 x 10(12) (T/K)(0.203) exp(-19 660 K/T) and 1.6 x 10(26) (T/K)(-3.06) exp(-21 121 K/T), respectively. A quantitative agreement with experimental data for GeH(4) decomposition could be obtained adopting a downward energy transfer parameter of 340 x (T/298 K)(0.85) cm(-1) in the collisional model, and assuming that atomic Ge can react fast with GeH(4) to form Ge(2)H(2) and H(2), thus enhancing the germane decomposition rate and suggesting that a fast kinetic route leading to the Ge(2)H(2) production can be active in the gas phase.

show abstract

Section: Discussionsupporting

confidence: 76%

Theoretical investigation of germane and germylene decomposition kinetics

Polino

Barbato

Cavallotti

2010

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…Less is known about the behavior of GeH 2 , and so we report further studies in the present paper. In addition to our investigations, − other kinetic studies have been undertaken by the group of King and Lawrance − in the gas phase and also by the group of Leigh in the liquid phase (mainly of organogermylenes) . These investigations showed that GeH 2 (and GeR 2 ) typically undergoes bond insertion reactions into Ge–H, Si–H, and O–H bonds, π-type addition reactions across CC and CC bonds, and reaction with lone pair donor molecules such as ethers.…”

Section: Introductionmentioning

confidence: 65%

“…Generally, for analogous reactions, efficiencies for GeH 2 are lower than those for SiH 2 , but often not by much. 10,14,18,33 Arrhenius parameter comparisons are shown in Table 6. This shows the common pattern of differences between reactions for GeH 2 and SiH 2 , viz.…”

Section: ■ Discussionmentioning

confidence: 99%

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

2014

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…4 In 1996, in collaboration with the group of Egorov and Nefedov, we reported the first rate coefficients for reactions of GeH 2 obtained by time-resolved means in the gas phase. 5 Since then we, [6][7][8][9][10][11][12][13][14][15][16][17][18] and the group of King and Lawrance, [19][20][21] have carried out a number of further detailed gas-phase kinetic studies of GeH 2 reactions, the results of which have been summarised in two recent reviews. 22,23 These investigations show that GeH 2 typically undergoes bond insertion reactions (into Ge-H, Si-H and O-H bonds), p-type addition reactions across CQC and CRC bonds and reaction with lone pair donor molecules such as ethers.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved gas-phase kinetic study of the germylene addition reaction, GeH2 + C2D2

Becerra¹,

Walsh²

2010

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

Time-resolved studies of germylene, GeH(2), generated by laser flash photolysis of 3,4-dimethyl-1-germacyclopent-3-ene, have been carried out to obtain rate coefficients for its bimolecular reaction with C(2)D(2). The reaction was studied in the gas phase, mainly at a total pressure of 1.3 kPa (in SF(6) bath gas) at five temperatures in the range 298-558 K. Pressure variation measurements over the range 0.13-13 kPa (SF(6)) at 298, 397 and 558 K revealed a small pressure dependence but only at 558 K. After correction for this, the second-order rate coefficients gave the Arrhenius equation: log(k infinity/cm3 molecule(-1) s(-)1) = (-10.96 +/- 0.05) + (6.16 +/- 0.37 kJ mol-1)/RT ln 10. Comparison with the reaction of GeH(2) + C(2)H(2) (studied earlier) showed a similar behaviour with almost identical rate coefficients. The lack of a significant isotope effect is consistent with a rate-determining addition process and is explained by irreversible decomposition of the reaction intermediate to give Ge((3)P) + C(2)H(4). This result contrasts with that for GeH(2) + C(2)H(4)/C(2)D(4) and those for the analogous silylene reactions. The underlying reasons for this are discussed.

show abstract

A comparison of the reactivity of germylene and dimethylgermylene with some methylgermanes. Direct kinetic and quantum chemical studies

Cited by 20 publications

References 48 publications

Theoretical investigation of germane and germylene decomposition kinetics

Theoretical investigation of germane and germylene decomposition kinetics

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

Time-resolved gas-phase kinetic study of the germylene addition reaction, GeH2 + C2D2

Contact Info

Product

Resources

About