Absorption, emission and reaction kinetics of dimethylsilylene

Shizuka, Haruo; Tanaka, Hideaki; Tonokura, Kenichi; Murata, Kazuyuki; Hiratsuka, Hiroshi; Ohshita, Joji; Ishikawa, Mitsuo

doi:10.1016/0009-2614(88)87371-8

Cited by 36 publications

(26 citation statements)

References 12 publications

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“…We have found kinetic evidence, in the form of biexponential decays, for an intermediate complex in the reaction of SiMez with dimethyl ether in the gas-phase [13]. Others [5,14,15] have measured rate constants for reactions of SiMez with alcohols with rates approaching diffusion control in solution [5,15]. As part of our continuing interest in kinetic and mechanistic aspects of silylene reactions [13, we report here on a study, carried out in the gas-phase at ambient temperatures, of the reactions of SiMez with a variety of oxygen-containing organic compounds using the time-resolved laser pump-probe technique to obtain absolute rate constants.…”

Section: Introductionmentioning

confidence: 95%

Time resolved kinetic studies of the gas‐phase reactions of dimethylsilylene with some O‐Donor molecules: Part I. Room temperature studies

Baggott

Blitz

Frey

et al. 1992

Int J of Chemical Kinetics

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The reactions of dimethylsilylene, SiMez, generated by laser flash photolysis from pentamethyldisilane and octamethyltrisilane, and detected via its 457.9 nm absorption, have been investigated with a number of oxygen containing molecules, including oxygen itself, carbon monoxide, water, alcohols, and ethers at 295 K. Some substrate molecules were deuterated. Apart from GO, all molecules reacted with SiMez with second order rate constants (in cm3 molecule-' s-l) in the range 7.7 x to 4.7 x lo-". While most of the reactions of SiMez studied went to completion those with dimethylether and tetrahydrofuran were partially reversible. The reaction of SiMep with oxirane was pressure dependent.The data are generally consistent with a mechanism involving initial formation of a donoracceptor, zwitterionic complex. In the case of reaction with alcohols, there is a small overall isotope effect, suggesting formation of a complex followed by rapid H-transfer, which only marginally affects the rate. In the case of ethers, complexes are formed which (i) may react further (MezSi . . . oxetane), (ii) may react further but also reversibly decompose (MezSi . . . oxirane), or (iii) do not seem to react further (MezSi . . .OMez, MezSi . . .THF) but partially redissociate.The donor-acceptor bond strength has been estimated in these last cases to be ca. 40 k J mol-I. Supporting arguments and mechanistic details of all reactions investigated are presented.

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Section: Introductionmentioning

confidence: 95%

Time resolved kinetic studies of the gas‐phase reactions of dimethylsilylene with some O‐Donor molecules: Part I. Room temperature studies

Baggott

Blitz

Frey

et al. 1992

Int J of Chemical Kinetics

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“…The chemistry of the parent molecule, SiH 2 , has been extensively characterized in the gas phase, chiefly by Walsh and his group [5], who have also carried out similar studies of SiMe 2 [6][7][8]. The latter silylene has been studied in detail in solution by Das and Shizuka and their coworkers, who measured absolute rate constants for reaction of the species in cyclohexane solution with alcohols, ethers, alkenes, alkynes, O 2 , trialkylsilanes, and tri-n-butylstannane and examined its complexation with ethers, amines, and acetonitrile [9][10][11][12]. A time-resolved study of the reactivity of dimesitylsilylene in hydrocarbon solvents has also been reported [13].…”

Section: Introductionmentioning

confidence: 98%

The photochemistry of a potential diphenylsilylene precursor. Time-resolved spectroscopic studies of the reactivity of a transient vinylsilirane

et al. 2006

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The photochemistry of 3,4-dimethyl-1,1-diphenylsilacyclopent-3-ene (2), a potential precursor to diphenylsilylene (SiPh 2 ), has been studied in hydrocarbon and methanol solution by steady state and laser flash photolysis techniques. The results are consistent with the formation of three major photoproducts: SiPh 2 (ca. 20%), 2,3-dimethyl-1,3-butadiene (DMB; ca. 20%), and 2-methyl-2-(1-methylethenyl)-1,1-diphenylsilirane (9; ca. 75%), the product of formal photochemical (1,3)-sigmatropic rearrangement of 2. Attempts to detect the silylene by laser flash photolysis were unsuccessful, but the vinylsilirane could be easily detected as a long-lived transient exhibiting λ max = 285 nm and lifetime τ = 1.3 s in hexane at 25 • C. The same spectrum is observed in neat methanol solution, where the lifetime of the species is shortened to τ = 36 ms and it is quenched by sodium methoxide and methanesulfonic acid with absolute rate constants of k MeO -= 2.0 × 10 6 M −1 s −1 and k H+ = 2.6 × 10 3 M −1 s −1 , respectively. The photochemistry of 2 is compared to that of the corresponding germanium homologue (1), whose photolysis in solution has been previously shown to afford diphenylgermylene and DMB cleanly and in high yields. The corresponding vinylgermirane (11a), though not detectable as a primary photoproduct from 1 in solution, is the exclusive product of photolysis of 1 in a 3-methylpentane glass at 78 K, where it exhibits an essentially identical UV/vis spectrum to that of 9. The rate constant for its unimolecular thermal isomerization to regenerate 1 is three orders of magnitude larger than that of the corresponding process in the homologous vinylsilirane (9) in hydrocarbon solution at 25 • C.

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“…Shizuka, Ishikawa and coworkers generated SiMe 2 in methylcyclohexane solution by irradiation of cyclo-(SiMe 2 ) 6 and obtained rate constants for reaction with MeOH and Et 3 SiH in good accord with gas-phase experiments 258 . Similar experiments in cyclohexane by Levin and coworkers gave similar rate constants for H O and H Si insertion reactions in the range 10 9 M 1 s 1 and rapid complexation of SiMe 2 with THF 257a .…”

Section: Kinetics Of Silylene Reactionsmentioning

confidence: 92%

Silylenes

Gaspar¹,

West²

2009

Patai's Chemistry of Functional Groups

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Introduction Generation of Silylenes Reactions of Silylenes Theoretical Calculations Spectroscopic Characterization of Silylenes Kinetics of Silylene Reactions Silylene–Transition Metal Complexes Special Topics Speculations on the Future of Silylene Chemistry

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Absorption, emission and reaction kinetics of dimethylsilylene

Cited by 36 publications

References 12 publications

Time resolved kinetic studies of the gas‐phase reactions of dimethylsilylene with some O‐Donor molecules: Part I. Room temperature studies

Time resolved kinetic studies of the gas‐phase reactions of dimethylsilylene with some O‐Donor molecules: Part I. Room temperature studies

The photochemistry of a potential diphenylsilylene precursor. Time-resolved spectroscopic studies of the reactivity of a transient vinylsilirane

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