74963-95-4Relevant academic research and scientific papers
Thermal decomposition of tetramethylsilane and tetramethylgermane by flash pyrolysis vacuum ultraviolet photoionization time-of-flight mass spectrometry
Lemieux, Jessy M.,Zhang, Jingsong
, p. 50 - 55 (2015/02/19)
Thermal decomposition of tetramethylsilane (TMS) and tetramethylgermane (TMG) was studied on a short time scale of 20100 ms using flash pyrolysis vacuum ultraviolet single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS). Primary decomposition of TMS and TMG occurred via loss of a methyl radical to form ?Si(CH3)3 and ?Ge(CH3)3, respectively. Both the ?Si(CH3)3 and ?Ge(CH3)3 radicals underwent secondary loss of a second methyl radical to form :Si(CH3)2 and :Ge(CH3)2, respectively. A previously unobserved secondary decomposition process in TMS involving loss of H atom from ?Si(CH3)3 followed by elimination of H2 to form SiC3H8, SiC3H6, and SiC3H4 was also identified. Sequential loss of the third and fourth methyl radical with significant formation of Ge and Ge2 was observed in the TMG pyrolysis. Loss of a third methyl radical in the TMS pyrolysis was not significant, while Si and SiC products were possibly produced. Secondary reactions of methyl to form unsaturated CxHy species, particularly in the TMG decomposition, were also observed.
Molecular beam photochemistry of organopolysilanes and organopolygermanes
Borthwick, Ian,Baldwin, Lawrence C.,Sulkes, Mark,Fink, Mark J.
, p. 139 - 146 (2008/10/08)
The molecular beam photochemistry of various polysilanes and polygermanes was investigated. In most cases, the precursor compounds were photolyzed in the nozzle region of a supersonic jet by a 193 nm laser and the photoproducts analyzed downstream by 118 nm photoionization pulses followed by time-of-flight mass spectrometry. The polysilane and polygermane compounds included in this study were PhMeSi(SiMe3)2, PhSi(SiMe3)3, (Me2-Si)6, (Me2Ge)6, and 1,3-diphenyl-1,2,2,3-tetramethyl-1,2,3-trisilacycloheptane. The 193 nm photoproducts of PhSiMe3, Me3SiSiMe3, and vinyltrimethylsilane were also examined for comparison purposes. Dimethylsilylene (Me2Si:) was directly observed as the major one-photon photoproduct from the cyclic precursors (Me2Si)6 and 1,3-diphenyl-1,2,2,3-tetramethyl-1,2,3-trisilacycloheptane. Likewise, dimethylgermylene (Me2Ge:) was directly observed in the photolysis of(Me2Ge)6. One-photon photolysis of the noncyclic polysilanes PhMeSi(SiMe3)2 and PhSi(SiMe3)3, however, gave radical products derived from the homolytic scission of a single Si-Si bond with little or no evidence of silylene being generated directly. A mechanism explaining the difference in photochemical outcome for cyclic vs noncyclic molecules is presented. Finally, molecular Si2C is found to be a ubiquitous product resulting from the multiphoton photochemistry of a number of organosilicon precursors.
Chemistry of heavy carbene analogues R2M (M = Si, Ge, Sn). XVII. Reactions of free dimethylgermylene with H-acidic compounds and donors
Klein, Beatrix,Neumann, Wilhelm P.,Weisbeck, Markus P.,Wienken, Stefan
, p. 149 - 159 (2007/10/02)
The free germylene Me2Ge, 1, inserts smoothly into O-H, S-H, or N-H bonds of water, deuterium oxide, alcohols, carboxylic acids, oximes and phthalimide to yield the (mostly new) substituted organogermanium hydrides of the type X-Me2Ge-H, 3, 5-12.The more
Electronic absorption spectra of diorganogermylenes in matrices: Formation of diorganogermylene complexes with heteroatom-containing substrates
Ando, Wataru,Itoh, Hiroyuki,Tsumuraya, Takeshi
, p. 2759 - 2766 (2008/10/08)
Diorganogermylenes were generated in hydrocarbon matrices at 77 K by the photolysis of 7-germanorbornadienes 1a-e or bis(trimethylsilyl)germanes 2a-g. The germylenes show electronic absorption bands at 420-558 nm. The germylenes react with heteroatom-containing substrates (R2O, R2S, R3P, R3N, RCl, and ROH) to form adducts, which show characteristic absorption bands at shorter wavelengths than those of germylenes.
Kinetic and labeling studies of the formation and trapping reactions of dimethylgermylene
Shusterman, Alan J.,Landrum, Bruce E.,Miller, Rebecca L.
, p. 1851 - 1855 (2008/10/08)
The kinetics of the thermal decomposition of 7,7-dimethyl-1,4,5,6-tetraphenyl-7-germabenzonorbornadiene (1) have been studied in the presence of excess styrene, 2,3-dimethylbutadiene, and CCl4. At 78.3°C the observed rate constant is 1.1 × 10-3 s-1 and is independent of the initial concentrations of 1 and the other reagents indicating a first-order, unimolecular decomposition. The same rate constant is also obtained without any added reagents. Activation parameters for the decomposition are ΔH? = 27.8 ± 0.6 kcal/mol and ΔS? = 6.8 ± 1.6 eu. The parameters are consistent with rate-determining cleavage of a single bridgehead germanium-carbon bond to give a diradical intermediate. Generation of dimethylgermylene from 1 in the presence of excess (E)-2-deuteriostyrene yields cis and trans isomers of 2,5-dideuterio-11-dimethyl-3,4-diphenylgermacyclopentane. The site of the deuterium label is partially scrambled and can be rationalized by postulating acyclic diradical intermediates for the cycloaddition process.
Transient and Matrix Ultraviolet Absorption Spectra of Dimethylgermylene (Dimethylgermanediyl)
Tomoda, Shuji,Shimoda, Masakatsu,Takeuchi, Yoshito,Kajii, Yoshizumi,Obi, Kinichi,et al.
, p. 910 - 912 (2007/10/02)
Dimethylgermylene (1), generated from a new precursor dimethylbis(phenylseleno)germane (2), has been observed as a transient species by time-resolved laser flash photolysis at room temperature.
Chemistry of heavy carbene analogues R2M (M = Si, Ge, Sn). 12. Concerted and nonconcerted insertion reactions of the germylene Me2Ge into the carbon-halogen bond
K?cher, Jürgen,Lehnig, Manfred,Neumann, Wilhelm P.
, p. 1201 - 1207 (2008/10/08)
During the reaction of Me2Ge with CCl3X (X = Cl, Br), PhCH2X (X = Br, I), and Ph2CHCl, 1H CIDNP is observed in the products of net insertion of Me2Ge into the carbon-halogen bond and in Me2GeX2 (X = Cl, Br). It is concluded that a two-step radical reaction takes place by an abstraction-recombination mechanism. No reaction takes place with alkyl halides that have a C-X bond dissociation energy of more than about 70 kcal/mol. Me2Ge is generated thermally at 70-95°C or photochemically from the 7-germabenzonorbornadiene 1 and reacts in both cases in the singlet state. The activation energy for forming Me2Ge from 1 is 19 kcal/mol for the reaction with CCl4. Insertion products are also formed with the alkenyl halides CH2=CHCH2X, PhCH=CHX (X = Cl, Br), and 2-bromobut-2-ene, but without showing CIDNP effects. Since Me2GeX2 was not found either, Me2Ge reacts in these cases in a nonradical manner. It does not react with 1-chlorocyclohexene, but it does react with Me2GeX2 under formation of digermanes and/or oligogermanes without CIDNP.
Photochemistry of Phenylpentamethyldigermane
Mochida, Kunio,Kikkawa, Haruhiko,Nakadaira, Yasuhiro
, p. 1089 - 1092 (2007/10/02)
Photolysis of phenylpentamethyldigermane afforded hydrogermanes and digermanes, as main products.These are derived from two germyl radicals generated by photo-induced homolysis of the germanium-germanium bond.Dimethylgermylene is shown to be evolved also
