Silylation as a protective method for terminal alkynes in oxidative couplings

Eastmond, R.; Johnson, T. R.; Walton, D. R. M.

doi:10.1016/0040-4020(72)80041-3

Cited by 324 publications

(203 citation statements)

References 25 publications

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“…However, the rupture during the actual photolysis most likely occurs with C 10 H 2 in an electronically excited state. Moreover, the interaction between the C 10 H 2 molecules and the solvent molecules is considerable, as shown by the $20 nm redshift of the so-called B-band UV absorption spectrum of polyynes from the gas phase to n-hexane solution (Kloster-Jensen et al 1974;Eastmond et al 1972). The strength of the À2-À3 bond and the geometry of the excited molecule in solution are unknown.…”

Section: Discussionmentioning

confidence: 99%

“…The photolysis of C 10 H 2 of this study was carried out in solution, because the synthesis of C 10 H 2 in the gas phase can lead to explosions, and because the absorption spectrum of C 10 H 2 in the gas phase is unknown. However, the absorption spectra of C 6 H 2 and C 8 H 2 are known both in solution and in the gas phase (Eastmond et al 1972;Kloster-Jensen et al 1974). The absorption spectra of C 6 H 2 and C 8 H 2 in the gas phase are blueshifted by approximately 20 nm relative to the solutions.…”

Section: Introductionmentioning

confidence: 99%

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On the Origin of Cometary C₂and C₃: Hydrogen Atom Migration in Diacetylene?

Heymann

2008

ApJ

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The photolysis of C 10 H 2 in air-saturated hexane by 253.6 nm photons yields the polyyne C 8 H 2 in approximately 5% of all C 10 H 2 disappearances; perhaps due to the migration of the hydrogen atom on À1 (I use the symbol Àn to designate the specific carbon atom number n in the chain; À1 is carbon atom 1) to À3 in the electronically excited C 10 H Ã 2 molecule followed by the rupture of the À2-À3 carbon-carbon bond. C 6 H 2 and C 12 H 2 were not seen to form. This new result strengthens the hypothesis that hydrogen migration along carbon chains of photon-excited polyynes followed by the rupture of one carbon bond could be very common among these compounds. It is suggested here that diacetylene forms photochemically from acetylene in the cometary coma followed by the swift photochemical formation of C 2 from diacetylene by hydrogen migration from À1 to À3 followed by the rupture of the À2-À3 carboncarbon bond. Hydrogen migration from À1 to À4 in excited diacetylene followed by the rupture of the À3-À4 carbon bond might form cometary C 3 . Neither C 2 nor C 3 were detected in the current study. Their formation by hydrogen migration is therefore hypothetical but the case for C 2 is observationally stronger than for C 3 . Removal of air from the solution increased the disappearance rate of C 10 H 2 by a factor of almost 10 3 , which implies that the excited molecule is in a triplet state with an estimated lifetime of 160 s.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the Origin of Cometary C₂and C₃: Hydrogen Atom Migration in Diacetylene?

Heymann

2008

ApJ

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“…The concentration of each species was measured on the basis of the absorbance of their most intense peak in the electronic absorption spectra by using the Lambert-Beer law and the molar extinction coefficients reported in the literature [35]. Typical distributions of chain lengths H-C N -H range from N = 6 up to N = 16 with a relative abundance maximum for N = 8 [28].…”

Section: Polyyne Productionmentioning

confidence: 99%

sp Carbon chain interaction with silver nanoparticles probed by Surface Enhanced Raman Scattering

Lucotti

Casari

Tommasini

et al. 2009

Chemical Physics Letters

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Surface Enhanced Raman Spectroscopy (SERS) is exploited here to investigate the interaction of isolated sp carbon chains (polyynes) in a methanol solution with silver nanoparticles.Hydrogen-terminated polyynes show a strong interaction with silver colloids used as the SERS active medium revealing a chemical SERS effect. SERS spectra after mixing polyynes with silver colloids show a noticeable time evolution. Experimental results, supported by density functional theory (DFT) calculations of the Raman modes, allow us to investigate the behaviour and stability of polyynes of different lengths and the overall sp conversion towards sp 2 phase.

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“…The most compelling example of T-interactions between Group 14 substituted alkynes is in the UV spectra of silyl-terminated polyynes. These are considerably red shifted compared with the H or C terminated polyynes (20,31). r-Interactions may arise from either (n-d)r or (p-d)r (32) (or (n-u*)r or (p-u*)r) interaction^.^ These would be anticipated to occur through u*-orbitals in the case of silicon; d orbitals are apparently not very important in the interaction with first-row elements (32,33).…”

Section: Discussionmentioning

confidence: 99%

Tetrakis[(trimethylsilyl)ethynyl] Group 14 metal derivatives: an examination of the electronic interaction between two Group 14 metals connected by an acetylene wire

Dallaire¹,

Brook²,

Bain³

et al. 1993

Can. J. Chem.

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The tetrakis(trimethylsilyl)ethynyl derivatives of Si, Ge, Sn, and Pb were prepared and examined spectroscopically. NMR and Mössbauer spectroscopy and X-ray crystal structure data clearly demonstrate an electronic interaction in the ground state between the distal SiMe3 groups and the central metal atom, leading to a strong shielding of the central metal atom; the respective nmr signals of the central metal are among the most shielded examples reported for a tetrahedral Group 14 metal centre with four carbon ligands. The nature of these electronic interactions is discussed.

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Silylation as a protective method for terminal alkynes in oxidative couplings

Cited by 324 publications

References 25 publications

On the Origin of Cometary C₂and C₃: Hydrogen Atom Migration in Diacetylene?

On the Origin of Cometary C₂and C₃: Hydrogen Atom Migration in Diacetylene?

sp Carbon chain interaction with silver nanoparticles probed by Surface Enhanced Raman Scattering

Tetrakis[(trimethylsilyl)ethynyl] Group 14 metal derivatives: an examination of the electronic interaction between two Group 14 metals connected by an acetylene wire

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Silylation as a protective method for terminal alkynes in oxidative couplings

Cited by 324 publications

References 25 publications

On the Origin of Cometary C2and C3: Hydrogen Atom Migration in Diacetylene?

On the Origin of Cometary C2and C3: Hydrogen Atom Migration in Diacetylene?

sp Carbon chain interaction with silver nanoparticles probed by Surface Enhanced Raman Scattering

Tetrakis[(trimethylsilyl)ethynyl] Group 14 metal derivatives: an examination of the electronic interaction between two Group 14 metals connected by an acetylene wire

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On the Origin of Cometary C₂and C₃: Hydrogen Atom Migration in Diacetylene?

On the Origin of Cometary C₂and C₃: Hydrogen Atom Migration in Diacetylene?