The Structure of Conjugated Open-chain Hydrocarbons

Popov, E. M.; Kogan, G. A.

doi:10.1070/rc1968v037n02abeh001619

Cited by 37 publications

(15 citation statements)

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“…This is due to the fact that the vibrational structure of the spectra is determined by structural changes in the molecules upon excitation that are relatively small for complicated molecules and of the same order as uncertainties of nonempirical methods, ≈0.01-0.05 Å for bond lengths and 1-5 o for bond angles [40][41][42][43]. Therefore, we used the aforementioned semi-empirical parametric methods in this work [34,35]. Table 1 lists calculated changes of bond lengths and bond angles in imidazole and structure II on transitioning into the first ππ * -electronic excited state.…”

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confidence: 99%

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Manifestation of intramolecular proton transfer in imidazole in the electronic-vibrational spectrum

Ten

Баранов

2008

J Appl Spectrosc

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539.194 Electronic-vibrational spectra of both imidazole (I) and the intermediate molecular structure (II) in the intramolecular proton transfer process N 1 H(I) → N 3 H(III) have been calculated and analyzed theoretically. The geometries of the molecular structures of I and II in the first ππ * excited state were determined using semiempirical correlations and the method of hybridized atomic orbitals. The difference in their spectra indicates that the intramolecular proton-transfer mechanism with imidazole (I ↔ III) tautomeric conversion can be identified by electronic-vibrational spectroscopy.

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confidence: 99%

“…Semi-empirical correlations [34] and a parametric method [35] are some of the most effective methods at present for determining parameters (geometry, force constants) of models of complicated molecules in electronic excited states. They can produce not only qualitative but also quantitative agreement with experimental spectra.…”

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confidence: 99%

Manifestation of intramolecular proton transfer in imidazole in the electronic-vibrational spectrum

Ten

Баранов

2008

J Appl Spectrosc

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“…At the present time, the most effective methods of determining the parameters (of the geometry force constants) of the models of complex molecules in excited electronic states that make it possible to obtain not only qualitative but also quantitative agreement with the spectral experiment are semiempirical correlations [18] and a parametric method [19]. For the most typical fundamental lines the error for the frequency is ∆ν ≤ 20-30 cm -1 and for the intensity is ∆I ≤ 15-20% [19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 98%

“…This is attributable to the fact that the vibrational structure of the spectra is determined by changes in the structure of molecules upon excitation, which are relatively small for complex molecules and commensurable with the errors of nonempirical methods, equal to +0.01-0.05 A° for the lengths of the bonds and 1-5 o for the valence angles [26]. Therefore, precisely the semiempirical parametric approaches [18,19] were used by us in the present spectral investigation.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the tautomerism of nucleic acid bases by electronic-vibrational spectroscopy

Ten

Баранов

2004

J Appl Spectrosc

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Some problems on the tautomerism of nucleic acid bases have been studied by theoretical vibronic spectroscopy. Structural-dynamic models of molecules in excited states have been constructed. Based on the analysis of the change in the geometry of a pair of nucleic bases (adenine-thymine) upon electronic excitation, one possible reason for the formation of rare tautomeric forms is considered. The vibrational structure of the absorption spectra of purine and adenine tautomers has been calculated. The possibility of identifying the tautomeric forms of purine and adenine for different phase states with the aid of electronic-vibrational spectra is shown.

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“…The reaction of thiols with polyalkynes is of interest in the synthesis of 1,2-dithiacyclohexa-3,5-dienes (1,2-dithiins) in general and of the bioactive thiarubrines in particular ; Rodriguez, Aregullin, Nishida, Uehara, Wrangham, Abramowski, delocalization of rr electrons in 1,3-dienes are topics of considerable discussion and controversy (Bartell, 1978;Dewar & Gleicher, 1965;Fischer & Michl, 1987;Popov & Kogan, 1968; Marias, Sheppard & Stoicheff, 1962;Simmons, 1970;Wiberg, Rosenberg & Rablen, 1991).…”

Section: Commentmentioning

confidence: 99%

(1Z,3Z)-1,4-Diphenyl-1,4-bis(p-tolylmethylthio)-1,3-butadiene

Freeman¹,

Lu²,

Rodríguez³

1995

Acta Crystallogr C

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FREEMAN, LU, ZILLER AND RODRIGUEZ 659H atoms were included using a riding model with d(C--H) = 0.96/I, and Uiso = 0.08 A :. Structure solution and refinement used either our locally modified version of the UCLA Crystallographic Package or the SHELXTL-Plus88 program set . Acta Cryst. (1995). C51, 659-661 (IZ,3Z)-1,4-Diphenyl-1,4-bis(ptolylmethylthio)-l,3-butadieneWe thank the National Institutes of Health (grant AI 24779) and the National Science Foundation (grant CHE-90-15849) for support of this research. Funds for the purchase of the Siemens R3m/V diffractometer system were made available from the National Science Foundation under grant CHE-85-14495. Lists AbstractThe crystal structure of (1Z,3Z)-1,4-diphenyl-1,4-bis-(p-tolylmethylthio)-l,3-butadiene (1), C32H3052, is described. Compound (1) has an s-trans conformation. The single bond length, C(2)---C(2'), in compound (1) (1)is comparable to that in 1,3-butadiene (1.34A). The short C--C single and double bonds in (1) may be attributed to delocalization (resonance) over the planar four-atom unit, hybridization changes, the presence of the S atoms, and/or other factors. CommentThe addition of p-tolylmethanethiol to 1,4-diphenyl- Freeman, Lu, Zeng & Rodriguez, 1994), or (Z)-1,4-diphenyl-1-(p-tolylmethylthio)but-1-en-3-yne (Zschunke, Mugge, Hintzche & Schroth, 1992) depending on the solvent system and the ratio of reactants. The reaction of thiols with polyalkynes is of interest in the synthesis of 1,2-dithiacyclohexa-3,5-dienes (1,2-dithiins) in general and of the bioactive thiarubrines in particular ; Rodriguez, Aregullin, Nishida, Uehara, Wrangham, Abramowski, delocalization of rr electrons in 1,3-dienes are topics of considerable discussion and controversy (Bartell, 1978;Dewar & Gleicher, 1965;Fischer & Michl, 1987;Popov & Kogan, 1968; Marias, Sheppard & Stoicheff, 1962;Simmons, 1970;Wiberg, Rosenberg & Rablen, 1991). CH3(1)In compound (1) the conformation of the 1,3-butadiene moiety is trans-planar. The planes of the two phenyl rings attached to C(1) and C(I') are both tilted 39.7 ° from the 1,3-butadiene plane. The single bond length, C(2)--C(2'), of 1.432 (5)A in compound (1) is shorter than the C(3)--C(4) bond (1.48A) in 1,3-butadiene and the double-bond length, C(1)---C(2), of 1.350 (3)A is comparable to that in 1,3-butadiene (1.34 A). The short C---C single and double bonds in (1) may be attributed to delocalization (resonance) over the planar four-C-atom unit, hybridization changes, the presence of the S atoms, and/or other factors. 1.388 (5) C(12)--C(13) 1.386 (4) C(13)--C (14) 1.387 (4) C(13)--C(16) 1.513 (6) C(14)--C (15) 1.384 (5) C(I)--S(1)--C (9) 100.1 (1)The structure was solved using direct methods (SHELXTLPlus88; and the UCLA Crystallographic Package . H atoms were located and included with isotropic temperature factors.We thank the National Institutes of Health (AI 24779) and the National Scince Foundation (grant CHE-90-15849) for support of this research. Funds for the purchase of the Siemens R3m/V diffractometer system were made a...

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The Structure of Conjugated Open-chain Hydrocarbons

Cited by 37 publications

References 2 publications

Manifestation of intramolecular proton transfer in imidazole in the electronic-vibrational spectrum

Manifestation of intramolecular proton transfer in imidazole in the electronic-vibrational spectrum

Investigation of the tautomerism of nucleic acid bases by electronic-vibrational spectroscopy

(1Z,3Z)-1,4-Diphenyl-1,4-bis(p-tolylmethylthio)-1,3-butadiene

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