A survey of carbon-carbon bond lengths

Lide, David R.

doi:10.1016/s0040-4020(01)99012-x

Cited by 190 publications

(92 citation statements)

References 41 publications

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“…139 pm). On the other hand, the CyC bond lengths (132±134 pm) do not differ very much from the CyC bond length in ethylene (133.7 pm [21]). So, the structural results indicate that no extended conjugation involving the C±C bonds occurs in the studied compounds.…”

Section: Ground State Propertiesmentioning

confidence: 69%

Spectroscopic characterization of α- and γ-pyrones and their substituted 4-hydroxy and 4-methoxy derivatives: an integrated infrared, photophysical and theoretical study

Melo

Quinteiro

Pina

et al. 2001

Journal of Molecular Structure

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The simple a-and g-pyrones and the substituted 6-methyl, 4-hydroxy and 4-methoxy a-pyrones were investigated in relation to their spectroscopic properties. The characterization involves vibrational and electronic spectroscopy. IR spectra for the ground electronic state of the studied compounds at room temperature were obtained and interpreted taking into consideration the simulated ab initio (6-31G p ) data. The most important canonical structures accounting for the properties of the ground state were determined for each compound and several photophysical properties were evaluated: electronic spectra, oscillator strengths and the emission properties (both¯uorescence and phosphorescence) in media of different polarity. The origin of the ®rst singlet and triplet excited states is also discussed. In addition, the energies of the electronic transitions were estimated using semi-empirical molecular orbital calculations, the calculated results showing an excellent agreement with the experimental data. q

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Section: Ground State Propertiesmentioning

confidence: 69%

Spectroscopic characterization of α- and γ-pyrones and their substituted 4-hydroxy and 4-methoxy derivatives: an integrated infrared, photophysical and theoretical study

Melo

Quinteiro

Pina

et al. 2001

Journal of Molecular Structure

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“…139 pm). Indeed, the C±C bond lengths in the pyrones (144.7±147.0 pm) were found to be similar to the central bond in butadiene (146.3 pm [18]), while the CyC bond lengths (132.7±133.5 pm) do not differ very much from the CyC bond length in ethylene (133.7 pm [19]). Other important conclusions are that in a-pyrone, a considerably strong repulsive interaction between the lone pairs of electron of the oxygen atoms is operating and that no signi®cant pelectron delocalization from O1 to the carbonyl group occurs.…”

Section: Experimental and Computational Detailsmentioning

confidence: 90%

Vibrational spectroscopy and ab initio MO study of the molecular structure and vibrational spectra of α- and γ-pyrones

Fausto

Quinteiro

Breda

2001

Journal of Molecular Structure

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The molecular structures and vibrational spectra of the monomeric forms of a-and g-pyrones were investigated by ab initio MO calculations, undertaken at the HF/6-31G p level of theory, and vibrational spectroscopy, including matrix-isolation FTIR spectroscopy. A complete assignment of the vibrational spectra of the studied compounds isolated in an argon matrix, at 8 K, or in the condensed phases, at room temperature, is presented and the vibrational data correlated with some important structural parameters. It is shown that the intermolecular interactions in the room temperature condensed phases do not affect the structure and vibrational properties of the studied molecules strongly, though the vibrational results clearly reveal minor changes induced in the carbonyl groups that indirectly affect the electron distribution in the whole pyrone rings, leading to an increase in their pelectron delocalization. For the isolated monomers, both structural and vibrational results point to a relatively weak p-electron delocalization in both a-and g-pyrone moieties. q

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“…The distances C1(3)...C1(5), C1(3)...C1(6) and C1(4)...C1(5) are 3.191 (2), 3.248 (2) and 3.273 (1)A, which minimize van der Waals repulsive interactions between neighbouring C1 atoms. This effect also results in a considerable shortening of the bonds C(7)-C1(3)= 1.754(5)A and C(8)-C1(5)= 1.751(5)A as compared to the standard C(sp3)-C1 distance of 1.781 (1)A (Lide, 1962), and a lengthening of the C(8)-C1(6) distance to 1.812 (4)A as in perchlorocyclopentadiene (Chang &Bauer, 1971) andtrans-2,2,3,4,5,6-hexachloro-6-methylcyclohex-3-enone (Hartshorn, Martyn &Vaughan, 1984). Due to the presence of the highly negative C1 substituents at vicinal C atoms, the C-O distance [1.178 (6)A] is slightly shortened (Hartshorn et al, 1984).…”

Section: Iihvc16no2mentioning

confidence: 99%

Structure of 5,5,7,7,8,8-hexachloro-4-methoxy-2-methyl-5,6,7,8-tetrahydro-6-quinolinone

Dhaneshwar¹,

Tavale²,

Row³

1986

Acta Crystallogr C

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A survey of carbon-carbon bond lengths

Cited by 190 publications

References 41 publications

Spectroscopic characterization of α- and γ-pyrones and their substituted 4-hydroxy and 4-methoxy derivatives: an integrated infrared, photophysical and theoretical study

Spectroscopic characterization of α- and γ-pyrones and their substituted 4-hydroxy and 4-methoxy derivatives: an integrated infrared, photophysical and theoretical study

Vibrational spectroscopy and ab initio MO study of the molecular structure and vibrational spectra of α- and γ-pyrones

Structure of 5,5,7,7,8,8-hexachloro-4-methoxy-2-methyl-5,6,7,8-tetrahydro-6-quinolinone

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