Infrared photochemistry of alkyl- and arylsilanes

IR laser­induced thermolysis and UV laser­induced photolysis of 1,3­diethyldisiloxane: chemical vapour deposition of nanotextured hydridoalkylsilicones

“…The observation that disiloxane and molecular hydrogen are the main products is in keeping with the occurrence of both paths. We note that these steps were also observed in the thermolysis of structurally similar monoorganosilanes: the infrared multiphoton decomposition of monoalkylsilanes was proposed to occur via a fourcentre elimination of silane 21,22 or 1,1-H 2 elimination, 23 and the shock-induced thermolysis of these compounds was interpreted as a blend of 1,2-H 2 and 1,1-H 2 elimination. 24,25 The minor extent of disiloxane decomposition via elimination and polymerization of silanone H 2 SiLO is supported by the presence of silane; this reaction is a well documented process when disiloxane is exposed to TEA CO 2 laser radiation.…”

“…Both reactors were equipped with a port for connecting it to a vacuum manifold, a PTFE valve and a sleeve with rubber septum. A TEA CO 2 laser (Plovdiv University) operating with a frequency 1 Hz on the R(12) line of the 00 0 1A10 0 0 transition (970.55 cm 21 ) was used for the thermolysis experiments; the laser beam was rectangular (0.561.7 cm) and was focused by a NaCl lens. An ArF (ELI 94 model) laser operating at 193 nm with a repetition frequency of 10 Hz and an incident energy of 70 mJ effective on the area of 2 cm 2 was used for the UV photolysis of DEDSO.…”

“…The progress of the DEDSO decompositions was monitored by periodically removing the reactors and placing them in the cell compartments of the FTIR (Nicolet Impact) spectrometer. The depletion of DEDSO was followed using its diagnostic absorption band at 1087 cm 21 and the accumulation of gaseous products was monitored by FTIR spectroscopy and by gas chromatography (a Shimadzu GC 14A chromatograph coupled with a Chromatopac C-R5A computing integrator, Porapak P column, programmed (20-150 ‡C) temperature, helium carrier gas). The hydrocarbon and organosilicon volatile products were identified on a Shimadzu model QP 1000 quadrupole mass spectrometer (ionizing voltage 70 eV).…”

β-hydride elimination processes on silicon

“…22, 23 Francisco and Schlegel have also proposed, based on their ab initio calculations for the photodissociation of gas phase monoethylsilane, that the 1,1-hydrogen elimination of H 2 to form C 2 H 5 SiH followed by ␤-hydride elimination of C 2 H 4 , was the lowest energy pathway to yield ethylene. Another possible reaction is ␣ elimination of hydrogen, followed by a hydrogen shift to yield ethylene.…”

Secondary dissociation pathways of ethylsilylene radical on ground and excited state potential energy surfaces

“…In order to understand the origin of Sill2 observed by laser-induced fluorescence (LIF) detection of Sill2 from infrared multiple-photon dissociation of ethylsilane [7,9], the relative importance of both primary and secondary dissociation pathways has to be examined. The net energy of activation for formation of Sill2 by CH3CH2SiH3 "-* CH3CH2SiH + H2 -~ C2H4 + Sill2 + H2 (10) is 325"9 kJ mol-~, as compared with the one-step photolysis channel,…”