Germanium atoms. Reactions with germane and silane

Gaspar, Peter P.; Levy, Carl A.; Frost, John J.; Bock, S. Allan

doi:10.1021/ja01034a073

Cited by 15 publications

(5 citation statements)

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“…Exactly similar and parallel arguments establish Et 2 GeHGeH 3 as the product of the GeH 2 + Et 2 GeH 2 reaction. These results confirm the formation of the expected products based on earlier studies of GeH 2 insertion into Ge−H bonds. − This approach was used previously to identify Me 3 SiGeH 3 as the product of GeH 2 + Me 3 SiH …”

Section: Discussionsupporting

confidence: 86%

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Direct Time-Resolved Study of the Gas-Phase Reactions of Germylene with Ethyl- and Diethylgermane: Absolute Rate Constants, Temperature Dependences, and Mechanism

et al. 2007

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Time-resolved studies of germylene, GeH2, generated by the 193 nm laser flash photolysis of 3,4-dimethyl-1-germacyclopent-3-ene, have been carried out to obtain rate constants for its bimolecular reactions with ethyl- and diethylgermanes in the gas phase. The reactions were studied over the pressure range 1-100 Torr with SF6 as bath gas and at five temperatures in the range 297-564 K. Only slight pressure dependences were found for GeH2 + EtGeH3 (399, 486, and 564 K). The high pressure rate constants gave the following Arrhenius parameters: for GeH2 + EtGeH3, log A = -10.75 +/- 0.08 and Ea = -6.7 +/- 0.6 kJ mol-1; for GeH2 + Et2GeH2, log A = -10.68 +/- 0.11 and Ea = -6.95 +/- 0.80 kJ mol-1. These are consistent with fast, near collision-controlled, association processes at 298 K. RRKM modeling calculations are, for the most part, consistent with the observed pressure dependence of GeH2 + EtGeH3. The ethyl substituent effects have been extracted from these results and are much larger than the analogous methyl substituent effects in the SiH2 + methylsilane reaction series. This is consistent with a mechanistic model for Ge-H insertion in which the intermediate complex has a sizable secondary barrier to rearrangement.

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Section: Discussionsupporting

confidence: 86%

“…These results confirm the formation of the expected products based on earlier studies of GeH 2 insertion into Ge-H bonds. [40][41][42] This approach was used previously to identify Me 3 SiGeH 3 as the product of GeH 2 + Me 3 SiH. 8 RRKM Calculations and Pressure Dependence.…”

Section: Discussionmentioning

confidence: 99%

Direct Time-Resolved Study of the Gas-Phase Reactions of Germylene with Ethyl- and Diethylgermane: Absolute Rate Constants, Temperature Dependences, and Mechanism

et al. 2007

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“…GeH 2 is known to be important in the chemical vapor deposition of semiconductor germanium, , and is the key intermediate in the breakdown mechanism of GeH 4 . Reaction 1 is known to occur when GeH 2 is made via recoil Ge atoms generated in the neutron bombardment in GeH 4 . It is reasonable to assume that reaction 1 is the likely second step in any process leading to the generation of Ge 2 H 6 from GeH 4 .…”

Section: Introductionmentioning

confidence: 99%

The Prototype Ge−H Insertion Reaction of Germylene with Germane. Absolute Rate Constants, Temperature Dependence, RRKM Modeling and the Potential Energy Surface

et al. 1998

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Time-resolved studies of germylene, GeH2, generated by laser flash photolysis of 3,4-dimethylgermacyclopentene-3, have been carried out to obtain rate constants for its bimolecular reaction with monogermane, GeH4. The reaction was studied in the gas phase over the pressure range 1−100 Torr, with SF6 as bath gas, at five temperatures in the range 292−520 K. The reaction of GeH2 with GeH4 to form digermane, Ge2H6, is pressure dependent, consistent with a third-body assisted association reaction. The high-pressure rate constants, obtained by extrapolation, gave the following Arrhenius equation: log(k ∞ /cm3 molecule-1 s-1) = (−11.17 ± 0.10) + (5.2 ± 0.7 kJ mol-1)/RT ln 10. These Arrhenius parameters are consistent with a moderately fast reaction occurring at approximately one-fifth of the collision rate. RRKM modeling, based on a variational transition state, used in combination with a weak collisional deactivation model, gave good fits to the pressure dependent curves, for a suitable choice of the critical energy, E o , for reverse decomposition of Ge2H6. The step size (energy removed in a down collision) was chosen by analogy with the corresponding system for Si2H6 (collisional efficiency (βc) of ca. 0.7 for SF6). The value obtained for E o was 155 kJ mol-1. Corrected for thermal energy and combined with the insertion activation energy this gives Δ H° = 166 kJ mol-1 for the decomposition of Ge2H6. There is no previous experimental determination of this quantity. From it we derive = 237 ± 12 kJ mol-1, in reasonable agreement with earlier estimates. From bond dissociation energy values the Divalent State Stabilization Energy (DSSE) of germylene (119 kJ mol-1) is larger than that of silylene (94 k J mol-1). Ab initio calculations at the correlated level reveal the presence of two weak complexes (local energy minima) on the potential energy surface corresponding to either direct or inverted geometry of the inserting germylene fragment. Surprisingly, the latter is the lower in energy, lying 25 kJ mol-1 below the unassociated reactants. These complexes rearrange to digermane with very low barriers. The implications of these findings and the nature of the insertion process are discussed.

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“…4 Our kinetic results 1 confirm that GeH 2 reacts rapidly with O 2 and with the π-bonds of alkenes and alkynes, and also inserts readily into Si-H bonds but not C-H bonds. GeH 2 is known to insert into Ge-H bonds 5,6 but to date only relative rate studies of this process have been carried out. 7 We report here an absolute rate study of the reaction of GeH 2 with Et 3 GeH, the first for GeH 2 with a molecule containing a Ge-H bond.…”

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confidence: 99%

“…End product analysis was not undertaken here since the products of the Ge-H insertion process are already known. [5][6][7] Experiments were carried out with gas mixtures containing a few millitorr of DMGCP, varying quantities of Et 3 GeH up to 500mTorr and inert diluent bath gas (SF 6 ) at a total pressure of 10Torr. The reaction was studied at five temperatures in the range 292-557K.…”

mentioning

confidence: 99%

Direct time-resolved study of the kinetics of the gas-phase reaction of germylene with triethylgermane: a negative activation energy for the Ge–H insertion process

Becerra

Боганов

Egorov

et al. 1997

Mendeleev Communications

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Germanium atoms. Reactions with germane and silane

Cited by 15 publications

References 0 publications

Direct Time-Resolved Study of the Gas-Phase Reactions of Germylene with Ethyl- and Diethylgermane: Absolute Rate Constants, Temperature Dependences, and Mechanism

Direct Time-Resolved Study of the Gas-Phase Reactions of Germylene with Ethyl- and Diethylgermane: Absolute Rate Constants, Temperature Dependences, and Mechanism

The Prototype Ge−H Insertion Reaction of Germylene with Germane. Absolute Rate Constants, Temperature Dependence, RRKM Modeling and the Potential Energy Surface

Direct time-resolved study of the kinetics of the gas-phase reaction of germylene with triethylgermane: a negative activation energy for the Ge–H insertion process

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