Substituent effects on acetylene stability. A comparison of STO-3G, 6-31G, 6-31G**, and 6-311G** calculations

Furet, Pascal; Hallak, George; Matcha, Robert L.; Fuchs, Richard

doi:10.1139/v85-496

Cited by 9 publications

(5 citation statements)

References 5 publications

(4 reference statements)

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“…[34] Substituent effects on nuclear spin-spin carbon-carbon coupling constants were studied in derivatives of acetylene. [35] The first extensive quantum chemistry-based study (calculations utilizing STO-3G, 6-31G, 6-311G* and 6-311G** basis sets) of substituent effect on acetylene derivatives stability [36] was based on the isodesmic methyl exchange reactions for 10 substituents. Substituent effects on the acidity of the acetylenic proton was studied on the LCAO-SCF-MO/STO-3G level of theory.…”

Section: Introductionmentioning

confidence: 99%

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives

Jabłoński

Krygowski

2020

ChemPhysChem

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The substituent effect is usually considered by means of various Hammett‐like substituent constants and is most often related to aromatic systems. Unlike this, we present results of our research on the influence of 27 substituents spanning a wide range of electronic properties, from strongly electron‐withdrawing to strongly electron‐donating, on the electron structure of X‐substituted acetylenes and diacetylenes – thus the systems which until now have practically not been subject of any deeper studies. It is shown that the interaction through triple bond(s) is associated with a significant advantage of resonance effects and that the substituent effect transmitted by the C≡C−C≡C unit is about half of that transmitted by the C≡C unit alone. Substituent X mainly affects the closest carbon atom by means of proximity effect, hence changes of charge on this atom do not follow any substituent constants. The effect on further carbon atoms is much smaller. The presence of the C≡C−C≡C unit withdraws more charge from X than a triple bond alone, and hinders communication between X and the terminal H atom. Comparison of substituent effects to those present in X‐substituted benzene derivatives shows that the electronic properties of the terminal hydrogen atom in acetylenes and diacetylenes are most similar to the electronic properties of ortho and para hydrogen atoms in X‐substituted benzene derivatives.

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Section: Introductionmentioning

confidence: 99%

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives

Jabłoński

Krygowski

2020

ChemPhysChem

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“…Most likely the first ab initio studies on substituted acetylene derivatives were performed by Powell et al [17] in 1983 and concerned the description of the influence of substituent effects on the acidity of an acetylene hydrogen atom. Then, substituent effects on acetylene stability were studied using isodesmic methyl exchange reactions [18]. Detailed NMR studies of substituted acetylene derivatives were performed by Kamienska-Trela et al [19] and Wiberg et al [20].…”

Section: Introductionmentioning

confidence: 99%

On differences in substituent effects in substituted ethene and acetylene derivatives and their boranyl analogs

Jabłoński

Krygowski

2020

Struct Chem

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This article is the first attempt to present different influence of substituent effects on double and triple bonds and, conversely, to present the impact of these bonds on the electronic structure of substituents. For this purpose, quantum-mechanical calculations were made for X-substituted derivatives of ethene and acetylene with 27 diverse substituents representing a wide spectrum of electronic properties, from strongly electron-accepting to strongly electron-donating ones. In addition to these systems, their boranyl derivatives are also investigated. It turns out that the Hammett substituent constants do not correctly describe changes in the CC bond length in any of the considered family of systems. However, the relationships with the CB bond length are significantly better. It is shown that the triple bond in acetylene derivatives is much more resistant to external perturbations than the double bond in the analogs containing an ethene unit. As a consequence, in acetylene derivatives, the substituent effects on CC bond length are about half of the substituent effects in ethene derivatives. We suggest that the observed lack of a clear linear correlation between the length of the CC triple bond in acetylene derivatives and the value of electron density on this bond is due to the disturbing additional interaction between the structure of the X substituent in the xy plane and the π bond being in the same plane in the acetylene unit—on the contrary, this interaction is not possible in ethene analogs.

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“…PA has two planar conformers ( cis and trans ) that differ by the orientation of the hydroxyl group and can interconvert to each other through internal rotation around the CO bond (in the conformers, the conformationally determining OCOH dihedral is equal to 0 and 180°, respectively; Figure ). Furet et al used quantum chemical calculations performed at several levels of theory with different basis sets to obtain the equilibrium geometry of the most stable conformer of PA ( cis form) and of other molecules of a series of acetylene derivatives. In another publication, the thermodynamic properties of saturated and unsaturated carboxylic acids including PA were determined .…”

Section: Introductionmentioning

confidence: 99%

“…It has been used in the synthesis of diarylalkynes, conjugated 1,3-diynes, 1,2-diketones, diarylalkynones, thioketones, substituted α-pyrones, − and coumarin and its derivatives, − which are used as fragrances, pharmaceuticals, and agrochemicals. PA is also believed to be present in interstellar space, as several fragments and molecules related to PA have been observed. − Some aspects of the structure and reactivity of the compound were investigated before, both experimentally and theoretically, which are summarized below. − …”

Section: Introductionmentioning

confidence: 99%

Propiolic Acid in Solid Nitrogen: NIR- and UV-Induced cis → trans Isomerization and Matrix-Site-Dependent trans → cis Tunneling

2019

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Propiolic acid (HCCCOOH, PA) was studied experimentally by infrared spectroscopy in a nitrogen matrix and by ab initio calculations. The vibrational spectra of the cis and trans monomers (OCOH dihedral equal to 0 and 180°, respectively) were measured and assigned. The trans-PA monomer was produced by selective vibrational excitation of the cis-PA monomer molecules trapped in different matrix sites. Broadband in situ UV irradiation (λ > 235 nm) of matrix-isolated PA yielded as product the higher-energy trans conformer, with no other photoproducts being detected. Two cis–cis dimers were also identified in the matrixes and characterized structurally and vibrationally. trans-PA was found to decay back to cis-PA in the dark, by tunneling, and the different lifetimes of the higher-energy PA conformer resulting from pumping different matrix sites and different experimental conditions (using a filter blocking the higher-energy IR radiation of the spectrometer source and without using such a filter) were discussed.

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Substituent effects on acetylene stability. A comparison of STO-3G, 6-31G, 6-31G, and 6-311G calculations

Cited by 9 publications

References 5 publications

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives

Changes in Electron Structure of the Triple Bond in Substituted Acetylene and Diacetylene Derivatives

On differences in substituent effects in substituted ethene and acetylene derivatives and their boranyl analogs

Propiolic Acid in Solid Nitrogen: NIR- and UV-Induced cis → trans Isomerization and Matrix-Site-Dependent trans → cis Tunneling

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