The Mercury 6(<sup>3</sup>P<sub>1</sub>) Photosensitization of the Methylsilanes and Silane

Nay, M. A.; Woodall, G. N. C.; Strausz, O. P.; Gunning, H. E.

doi:10.1021/ja01080a009

Cited by 85 publications

(20 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar observations have been made for other bimolecular reactions of the hydroxyl radical [I, 21. Although Arrhenius graph curvature is expected from bimolecular rate theory [5] and should be regarded as a rule than an exception on any theoretical basis, there appears to be no common single property of a reaction to which non-Arrhenius behaviour may be related. A number of explanations, including the rate enhancement of specific rate constants k, upon internal excitation of the reactants, potential surface crossing and multiple channels and statistical and dynamical factors in excitations functions (a(&)) may be put forward.…”

Section: Theoretical Interpretation Of K ( T )mentioning

confidence: 99%

Temperature Dependence of the Reaction OH + OH → H₂O + O

Wagner

Zellner

1981

Ber Bunsenges Phys Chem

View full text Add to dashboard Cite

this value with older estimates. However, it is appropiate to make such a comparison with the elaborate calculations of Ahlrichs and Heinzmann [20], who obtain E,(Me,Si= CH3 = 191 kJ/mol. The fact that the "experimental" and the calculated values for the A bond energy are virtually identical is certainly of no great significance for various reasons, one being the different way of defining En, another the uncertainties in the numbers used for the estimation of En. What is important, however, is that theory and experiment agree on a high value for the A bond energy.A similar good agreement exists for the enthalpy of reaction (6) (AH(6)ca,c = -318 kJ/mol vs. AZf(6),,, = -305 kJ/mol;The only apparent disagreement between theory and experiment exists for E,(6) for which Ahlrichs and Heinzmann calculate a value 5 58 kJ/mol for a plane-rectangular approach of the two Me,Si = CH, entities. The analogous "symmetryforbidden" cycloaddition of ethylene becomes formally "allowed" when the reaction path symmetry is reduced from D,, to C,, by a nuclear displacement towards a parallelogram [21]. In the head-to-tail dimerization of Me,Si = CH,, C,, symmetry is maintained even along the rectangular approach, but it might be conceivable that the calculated activation energy would drop to a very small value if the restriction: 4 SiCSi = 4 CSiC = 90" were relaxed.In conclusion one can say that 2-methyl-2-silapropene is a thermodynamically quite stable molecule. Its frequent appearance not only in photochemical and pyrolytic reactions but also in radical disproportionation reactions is therefore understood. On the other hand, despite its high A bond energy, the molecule acts kinetically more like a biradical which is probably due to the high polarisation of the A bond [20].We thank Prof. A. E. Halevi for valuable contributions.

show abstract

Section: Theoretical Interpretation Of K ( T )mentioning

confidence: 99%

Temperature Dependence of the Reaction OH + OH → H₂O + O

Wagner

Zellner

1981

Ber Bunsenges Phys Chem

View full text Add to dashboard Cite

show abstract

“…A compound excepted from the ge neral t.rend of CH3 produc ti on is CH2SiH Clz whe re simple Si-C fi ssion cann ot ex plain the triple t spectrum obse rv ed with components separated by -20 X 10 -4 T. That the observed result stems fro m rapid secondary or co mpetiti ve processes involving both Si-C a nd Si-H bonds was considered in the macro-irradiatio n expe ri · me nt, and the interesting apparent 4 dominan ce of H2 production over CH4 definitely requires consideration of an additional consecutive mechanism involving possibly both H~C and Si-H bonds [10]. Thus , if we assume initial Si-C cleavage analogous to that of CH3 SiCb a nd th e C H3 • is s uffi ciently mobile to imm ediately abstract a proton from a nearby pare nt molec ul e [2J, several reacti o n co urses are possibl e:…”

Section: Special Case Of Methyldichlorosilanementioning

confidence: 95%

The effects of low energy irradiation on organometallics. Organometal halides of group IVA

Brinckman¹,

Kokoszka²,

Adams³

1969

J. RES. NATL. BUR. STAN. SECT. A.

View full text Add to dashboard Cite

A group of se lected group IV A ha lide s of th e t ype (C H3)" MCI , _", wh e re n = 0 , 1,3 and M = S i, Ce, S ,) have bee n s ubjecte d to low-e ne rgy irrad iation (254 and 370 nm ) in th e co nd e nsed phase at -196 0 C.Thi s s urvey also e xamin ed re late d compound s in c ludin g HSiCh , CH,C ISiCl., CH3S iF3 , CH3SiHCI, a s we ll as coco nd e nsed mixtures. It is d e mon s tra ted by EPR s pectrosco p y that these co nditi ons s uffi ce to cleave M-C bonds. By foll owin g spectral c han ges during or followi ng irradiation, a s a function of tim e, it is de mon s trated that both primary and seco nd a ry reac tion s occ ur. So me general feature s of th e s pectra are di sc usse d and ce rtain co nc lu s ion s a re proj ec ted to additiona l studi es on low te mpe rature reactiun s in 1:1 coco nd e nsed mixtures of orga nometal halid es. So me pre liminary supporting ev id e nce from ma ss s pec trome tri c observat ions is di sc usse d.

show abstract

“…[29] Investigations on the mercury sensitized photolysis of trimethylsilane showed that fragmentation into trimethylsilyl and hydrogen radicals (BDE ¼ 378 kJ Á mol À1 ) proceeds, which then yields H 2 and (CH 3 ) 6 Si 2 as reaction products. [15] When UV irradiation of TMS was carried out with an ArF excimer laser (l ¼ 193 nm), also CH 4 and (CH 3 ) 4 Si were detected by FT-IR. [30] From this it can be concluded that Si-H scission is the predominant photolytic reaction for TMS, while Si-C fragmentation occurs to a lesser extent.…”

Section: General Aspectsmentioning

confidence: 99%

“…For trialkylsilanes such as trimethylsilane (TMS) the homolytic cleavage of the R 3 Si-H bond is the predominant photoreaction. [15] For the Si-H bond in trimethylsilane the bond dissociation energy (BDE) amounts to 378 kJ Á mol À1 , [16] which compares to the BDE of hydrocarbons. The BDE of the Si-H bond is especially low for tris(trimethylsilyl)silane (BDE ¼ 330 kJ Á mol À1 ) which therefore is an excellent hydrogen donor.…”

Section: Introductionmentioning

confidence: 99%

Modification of Polyethylene by VUV Irradiation in the Presence of Trimethylsilane and Oxygen

Daschiel

Spanring

Ebel

et al. 2008

Macro Chemistry & Physics

View full text Add to dashboard Cite

The photoassisted modification of LDPE by VUV irradiation in a reactive trimethylsilane/oxygen atmosphere was investigated. The modified LDPE surface was investigated by FT‐IR, XPS, contact‐angle measurements and electron microscopy. Attachment of alkylsilyl and Si–O units to LDPE was observed. Best results were obtained using an equimolar trimethylsilane/oxygen mixture. Low‐energy surfaces were obtained after a few minutes of irradiation at an intensity of 1.7 mW · cm−2. After prolonged irradiation, the thickness of the modified polyethylene layer is approximately 700 nm. Surface modifications of this type may be of interest to obtain protective and barrier layers on polyolefins.magnified image

show abstract

The Mercury 6(³P₁) Photosensitization of the Methylsilanes and Silane

Cited by 85 publications

References 2 publications

Temperature Dependence of the Reaction OH + OH → H₂O + O

Temperature Dependence of the Reaction OH + OH → H₂O + O

The effects of low energy irradiation on organometallics. Organometal halides of group IVA

Modification of Polyethylene by VUV Irradiation in the Presence of Trimethylsilane and Oxygen

Contact Info

Product

Resources

About

The Mercury 6(3P1) Photosensitization of the Methylsilanes and Silane

Cited by 85 publications

References 2 publications

Temperature Dependence of the Reaction OH + OH → H2O + O

Temperature Dependence of the Reaction OH + OH → H2O + O

The effects of low energy irradiation on organometallics. Organometal halides of group IVA

Modification of Polyethylene by VUV Irradiation in the Presence of Trimethylsilane and Oxygen

Contact Info

Product

Resources

About

The Mercury 6(³P₁) Photosensitization of the Methylsilanes and Silane

Temperature Dependence of the Reaction OH + OH → H₂O + O

Temperature Dependence of the Reaction OH + OH → H₂O + O