A gas electron diffraction study of the molecular structure of cis-stilbene

Trætteberg, M.; Frantsen, E.B.

doi:10.1016/0022-2860(75)80067-6

Cited by 101 publications

(47 citation statements)

References 13 publications

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“…[28][29][30] As a result, the repulsion between rings may well exceed possible stabilizing interactions. [28][29][30] The torsion angle along the ethylenic double bond is 20.98, which is larger than the optimum for cis-stilbene obtained from ab initio calculations [31] or gas-phase electron diffraction experiments [32] (6 and 58, respectively). On the other hand, the average phenyl rotation angle of approximately 298 out-of-plane is smaller than those given in the literature (40 and 438, respectively), [31,32] and this is probably due to the molecules attempt to achieve a more planar conformation for p-p stacking with a neighbor.…”

Section: Resultsmentioning

confidence: 95%

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Phototransformation of Stilbene in van der Waals Nanocapsules

Ananchenko

Udachin

Ripmeester

et al. 2006

Chemistry A European J

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We have utilized para-hexanoylcalix[4]arene nanocapsules as hosts to carry out phototransformations of cis- and trans-stilbene. Single-crystal X-ray diffraction studies were performed to define precisely the location of encapsulated stilbenes inside the capsule and to analyze possible pathways of phototransformation. cis-Stilbene stacks as a pi-pi dimer located at the center of the capsule, whereas trans-stilbene does not form such a dimer. Irradiation of the crystalline inclusion complexes of each isomer of stilbene in the solid state leads to the appearance of the second isomer, and after prolonged photolysis, photodimerization also occurs. syn-Tetraphenylcyclobutane is formed as the major product of dimerization and its yield depends on the time and intensity of irradiation. In most cases, the single crystals of the complexes remain intact during irradiation; hence, the nanocapsules have the potential to serve as robust nanoreactors in the solid state. The confinement in the nanocapsules is sufficient to keep the reacting molecules together, although this is less restrictive than for trans-stilbene crystals, in which the molecules cannot achieve a favorable orientation for dimerization.

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Section: Resultsmentioning

confidence: 95%

“…The entire "dimer" appears to be a compromise between p-electron stabilization of a single cis-stilbene molecule and p-p interaction of the two molecules. Notably, our attempts to fix the aforementioned angles according to literature values [31,32] did not improve the quality of refinement of the structure.…”

Section: Resultsmentioning

confidence: 98%

Phototransformation of Stilbene in van der Waals Nanocapsules

Ananchenko

Udachin

Ripmeester

et al. 2006

Chemistry A European J

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“…43" about the C-Ph bonds. The latter were thus treated as nonconjugattd bonds: e8 = 86.89 kcal mol-' was deduced for Rcc = 1.49 A, which is the experimental bond length (43). Similarly, the gas phase value (44) for the torsional angle about the central bond of biphenyl, 41.6", and its bond length, R = 1.49 A (17,45), suggest that the central bond should be treated like a nonconjugated CC single bond, thus giving ecc = 88.68 kcal mol-'.…”

Section: Discussionmentioning

confidence: 99%

Charge distributions and chemical effects. XL. Chemical bonds in benzenoid hydrocarbons

Fliszár¹,

Cardinal²,

Baykara³

1986

Can. J. Chem.

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Benzenoid hydrocarbons were examined using a bond energy scheme featuring the role of atomic charges. The latter were conveniently deduced from appropriate correlations between theoretical results and 13C nuclear magnetic resonance shifts. Atomization energies calculated in this manner agree with their experimental counterparts to within 0.36 kcal mol-1 (average deviation). It appears that benzenoid hydrocarbons can be efficiently described in terms of local charge density properties. In the absence of any distinctive specific feature characterizing benzenoids, this particular description of chemical bonds ultimately results in a unifying genealogy smoothly relating to one another the various possible types of CC and CH bonds which are formed by sp2 and sp3 carbons.

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“…As the benzene rings remain essentially planar, the steric hindrance must be relieved by rotating the Ph groups out of coplanarity with the central C=C bond and/or by twisting about this bond. Electron-diffraction studies of 3 [20] and theoretical calculations for 3 and 3'-indicate that the problem of the steric hindrance is met in both ways. Whereas, in the neutral molecule, it is relieved mainly by rotating the Ph groups, twist about the central bond becomes more effective in the radical anion.…”

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confidence: 95%

Effect of non‐planarity on the spin distribution in the radical anions containing the stilbene or the azobenzene π‐system: An ESR and ENDOR Study

Gerson¹,

Lamprecht²,

Scholz³

et al. 1996

Helvetica Chimica Acta

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The radical anions of 5H-dibenzo [a,d]cycloheptene (9), 5H-dibenzo[c,fl[ 1,2]diazepine (lo), 5,6-dihydrodibenzo[a,e]cyclooctene (1 l), 5,6-dihydrodibenzo[c,g][ 1,2]diazocine (It), and (E)-2,2,5,5-tetramethyl-3,4-diphenylhex-3-ene (13) were characterized by ESR and ENDOR spectroscopy. Their hyperfine data were compared with those previously reported for radical anions also containing the stilbene or the azobenzene n-system. Whereas the n-spin distribution in the radical anions of the stilbene series is only moderately sensitive to deviations of the n-system from planarity, the radical anions of the azobenzene series respond to steric strain by shifting the n-spin population from the benzene rings to the azo group. This finding is impressively demonstrated by the similar hyperfine data for 9'-and 11'-which contrast with the strongly differing ones for their azo counterparts 10'-and 12'-, as well as by the corresponding values for sterically highly hindered 13'-. A plausible interpretation is readily provided by the electron affinities of the constituent n-moieties in stilbene and azobenzene. While those of benzene and ethene are both comparatively low, the azo group has a considerably higher electron affinity.Introduction. -The isoelectronic (E)-stilbene (1) and (E)-azobenzene (2) belong to the basic organic compounds of which radical anions were first investigated by ESR spectroscopy 30 years ago [l-31, and which have since been repeatedly studied by ESR and ENDOR techniques [4][5][6]. Due to the pronounced electron affinity of the azo group, the half-wave potential of 2 (-1.38 V vs. SCE [6]) is markedly less negative than that of 1 (-2.22 V [7]). Despite this difference, the radical anions 1'-and 2'-have a similar 71-spin distribution which is evidently governed by the same topology of their 71 -systems. It may, however, be argued that this distribution will be affected differently by deviations of the 71-system from planarity.Conversion of 1 and 2 into their corresponding (2)-isomers 3 and 4 is a straightforward way to increase such deviations. Both radical anions, 3'-and 4'-, are not persistent because they rapidly isomerize to 1'-and 2'-, respectively. Nevertheless, 3'-could be

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A gas electron diffraction study of the molecular structure of cis-stilbene

Cited by 101 publications

References 13 publications

Phototransformation of Stilbene in van der Waals Nanocapsules

Phototransformation of Stilbene in van der Waals Nanocapsules

Charge distributions and chemical effects. XL. Chemical bonds in benzenoid hydrocarbons

Effect of non‐planarity on the spin distribution in the radical anions containing the stilbene or the azobenzene π‐system: An ESR and ENDOR Study

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