Dimethylsilylene: its optical absorption spectrum and reaction kinetics

Nazran, A. S.; Hawari, Jalal; Griller, D.; Alnaimi, I. S.; Weber, William P.

doi:10.1021/ja00335a080

Cited by 19 publications

(3 citation statements)

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“…The following three series demonstrate this point: ButSiMe (470 nm) > EtSiMe (459 nm) > Me2Si (453 nm); ButSiMes (505 nm) > BufCH2SiMes (500 nm) > MeSiMes (496 nm); Mes2Si (577 nm) 1) > PhSiMes (530 nm) > Ph2Si (495 nm).3 Finally we comment on the discrepancy between the two reported A, , , , values for Me2%: 450 nm according to West et ~l . ~a --~, 3 and 350 nm according to Griller et al 4 Unfortunately at the present level of theory the calculated absolute excitation energies are not sufficiently reliable for deciding decisively between these values. Kowever, the calculated AE values and the general good agreement between our calculations and 11 Calculations show that at ar>125" H2Si is a ground state triplet.…”

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confidence: 86%

The effect of substituents on the first transition in the visible spectra of silanediyls (silylenes)

Apeloig¹,

Karni²

1985

J. Chem. Soc., Chem. Commun.

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confidence: 86%

The effect of substituents on the first transition in the visible spectra of silanediyls (silylenes)

Apeloig¹,

Karni²

1985

J. Chem. Soc., Chem. Commun.

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“…Starting in 1987, absolute rate coefficients became available through the employment of techniques of timeresolved laser flash photolysis. By this means more detailed kinetic and mechanistic information about the behaviour of SiMe 2 both in the gas phase [9][10][11][12][13] and in solution [14][15][16][17][18][19][20] has been obtained in recent years. We recently reviewed this growing database.…”

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confidence: 99%

Time-resolved gas-phase kinetic studies of the reaction of dimethylsilylene with triethylsilane-1-d: kinetic isotope effect for the Si–H insertion process

Becerra

Cannady

Walsh

2013

Phys. Chem. Chem. Phys.

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Time-resolved kinetic studies of the reaction of dimethylsilylene, SiMe2, generated by laser flash photolysis of 1,1-dimethyl-1-silacyclopent-3-ene, have been carried out to obtain rate coefficients for its bimolecular reactions with trimethylsilane-1-d, Me3SiD. The reaction was studied in the gas phase at five temperatures in the range 292-605 K. The rate coefficients showed no pressure dependence in the presence of up to 13 kPa of SF6. The second order rate coefficients obtained at 0.7 kPa fitted the Arrhenius equation: log(k/cm(3) molecule(-1) s(-1)) = (-13.53 ± 0.19) + (11.29 ± 1.46) kJ mol(-1)/RT ln 10. By comparison with rate coefficients obtained previously for the reaction of SiMe2 with Me3SiH, a set of kinetic isotope effects, kH/kD, of value ca. 1.2 showing very little temperature dependence was obtained. Theoretical support for these values has been obtained by means of quantum chemical calculations used in conjunction with transition state theory. This study provides the first comprehensive set of kinetic isotope effects for the Si-H(D) insertion process of a silylene in the gas phase.

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“…450 nm [3a]. Although there was a controversy concerning the absorption spectra of dimethylsilylene [4], recent extensive spectroscopic studies by using matrix isolation [3,51, laser flash photolysis [6], and theoretical calculations [7,8] have confirmed that the 450 nm absorption is ascribed to the n(Si)-3p(Si) transition of singlet dimethylsilylene. Intriguing experimental targets in silylene chemistry involve (1) generation and characterization of silylenes having a triplet ground state and (2) synthesis and isolation of stable singlet silylenes as pure substances.…”

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Matrix‐isolation and electronic structure of vinyl‐substituted silylenes and their complexes with bases [1]

Kira

Maruyama

Sakurai

1994

Heteroatom Chemistry

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Vinyl-substituted silylenes, 2,5-bis(methylene)-l -silacyclopentane-l ,l -diyl (1) and 2-methybne-1 -silacyclopentane-1 ,I -diyl (2), generated photochemically from the corresponding trisilanes in 3-methylpentane (3-MP) at 77 K, showed broad bands at 505 INTROD UCTICINGeneration, structure, and reactions of divalent silicon species, silylenes, have been extensively studied as important reactive intermediates both experimentally and theoretically [2]. The electronic structure of silylenes has been discussed more Dedicated to Prof. Adrian Gibbs Brook on the occasion of his "To whom correspondence should be addressed. seventieth birthday.in-depth since the first matrix isolation of dimethylsilylene by Drahnak et al. in 1979 [3a]; they observed that dimethylsilylene produced by the irradiation of dodecamethylcyclohexasilane in an argon matrix at 10 K or in a 3-methylpentane (3-MP) glass matrix at 77 K showed a characteristic absorption maximum at ca. 450 nm [3a]. Although there was a controversy concerning the absorption spectra of dimethylsilylene [4], recent extensive spectroscopic studies by using matrix isolation [3,51, laser flash photolysis [6], and theoretical calculations [7,8] have confirmed that the 450 nm absorption is ascribed to the n(Si)-3p(Si) transition of singlet dimethylsilylene. Intriguing experimental targets in silylene chemistry involve (1) generation and characterization of silylenes having a triplet ground state and (2) synthesis and isolation of stable singlet silylenes as pure substances. Systematic studies of the electronic and steric effects of substituents on the structure and reactivity of silylene would be required in order to achieve these goals. There have been very limited studies of the substituent effects reported [9] because of difficulty in the generation and matrix isolation of desired silylenes.We report herein the isolation of vinyl-substituted silylenes, 1 and 2, in 3-MP and 2-methyltetrahydrofuran (2-MeTHF) matrices at 77 K [lo]. In disagreement with a recent theoretical prediction 171, the n(Si)-3p(Si) absorption maxima for the vinylsilylenes in 3-MP is shifted to a significantly longer wavelength than that for dimethylsilylene. The origin of the red shift is discussed in terms of the substantial conjugation between the vacant vinyl n-" and 3p(Si) orbitals.A number of experimental

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Dimethylsilylene: its optical absorption spectrum and reaction kinetics

Cited by 19 publications

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The effect of substituents on the first transition in the visible spectra of silanediyls (silylenes)

The effect of substituents on the first transition in the visible spectra of silanediyls (silylenes)

Time-resolved gas-phase kinetic studies of the reaction of dimethylsilylene with triethylsilane-1-d: kinetic isotope effect for the Si–H insertion process

Matrix‐isolation and electronic structure of vinyl‐substituted silylenes and their complexes with bases [1]

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