Infrared, Density-Functional Theory, and Atoms in Molecules Method Studies on Conformers of Some 2-Substituted 1<i>H</i>-Pyrroles

Dubis, Alina T.; Grabowski, Sławomir J.

doi:10.1021/jp030554z

Cited by 25 publications

(39 citation statements)

References 40 publications

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“…[1] The intermolecular HB interaction between two molecules of pyrrole-2-carbaldehyde derivatives has been studied by means of spectroscopic, diffraction, and theoretical methods including the Bader theory of atoms in molecules. [2][3][4][5] The calculated HB energy for these dimers is comparable with the HB energy found for many typical acid dimers. [6] Its value is À6.90, À6.23, À6.45, À6.63, À5.26, and À5.90 kcal/mol for a single N-H⋯O interaction within the pyrrol-2-carbaldehyde dimer, [7] pyrrol-2-yl methyl ketone dimer, pyrrol-2-yl dichloromethyl ketone dimer, pyrrol-2-yl trichloromethyl ketone, [5] and pyrrole-2-carboxylic acid dimers, [3] respectively.…”

Section: Introductionsupporting

confidence: 65%

“…Electron density at the H⋯Y BCP is also an indicator of HB strength because correlations between this value and the other descriptors of an HB interaction have been found. [26] To acquire better insight into a nature of the intramolecular interactions within 2-acylpyrrole molecules (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), their electronic structure were also characterized by natural bond orbital (NBO)-based charge transfer descriptors such as perturbative energy lowering ΔE n → σ* . [27] The main goal of this work was to discuss whether QTAIM topological parameters in connection with NBO analysis could be an effective tool for the recognition of an intramolecular interaction within a set of 2-acylpyrroles 1-20 (Scheme 2).…”

Section: Introductionmentioning

confidence: 99%

“…The following theoretical methods were applied: DFT B3LYP/aug-cc-pVDZ calculations, QTAIM theory, [28] and NBO analysis. [29] To the best of our knowledge, neither NBO nor topological data of intramolecular interactions within 2-acylpyrroles (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) have been calculated or discussed earlier.…”

Section: Introductionmentioning

confidence: 99%

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Can 2‐acylpyrroles form an intramolecular hydrogen bond?

Dubis

Stasiewicz

Pogorzelec‐Glaser

et al. 2015

J of Physical Organic Chem

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The formation of intramolecular hydrogen bonding by certain N-substituted 2-acylpyrroles has been demonstrated by B3LYP/aug-cc-pVDZ calculations, the quantum theory of atoms in molecules, and the natural bond orbital method. Total electron energy densities H BCP at the bond critical point of the H⋯O bond were applied to analyze the strength of these interactions. The relations between quantum theory of atoms in molecules, carbonyl stretching vibrational modes ν C = O , and natural bond orbital parameters associated with the formation of the C-H⋯O interaction have been established. The short contacts were found experimentally in the crystal structure of a new 2-acylpyrrole derivative 5-chloro-2-oxopentyl-1-(5-chloro-2-oxopentyl)pyrrolo-2-carboxylate. The influence of 2-and N-substitution of 2-acylpyrroles on C-H⋯O interaction energy is discussed. It was found that the methylene group may act as a proton donor leading to a red-shift or blue-shift phenomenon of the ν C-H stretching mode.

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Section: Introductionsupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Can 2‐acylpyrroles form an intramolecular hydrogen bond?

Dubis

Stasiewicz

Pogorzelec‐Glaser

et al. 2015

J of Physical Organic Chem

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“…The existence of both N,O-cis and N,O-trans conformations has been detected by FTIR for a series of 2-pyrrolyl chloromethyl ketones and 1-methyl-2-pyrrolyl chloromethyl ketones in cyclohexane solution [38]. In this case, the conformational stability is, however, governed Populations of individual conformers (P in %) are also tabulated [39][40][41][42][43][44][45], indicate that their N,O-cis conformers possess lower total electron energies than the respective N,O-trans conformers, which fully corresponds with the energetic ordering of the cc-and tt-conformers for 4a and 5a.…”

Section: Relative Energiesmentioning

confidence: 99%

Conformers of diheteroaryl ketones and thioketones: a quantum chemical study of their properties and fundamental intramolecular energetic effects

Matczak

Domagała

2015

Struct Chem

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The conformational behavior of ten diheteroaryl ketones and thioketones is investigated using various quantum chemical methods. These ketones and thioketones are formed by the disubstitution of formaldehyde and thioformaldehyde with such a heteroaryl group as 2-furanyl, 2-thiophenyl, 2-selenophenyl, 2-pyrrolyl or 1-methyl-2-pyrrolyl. For these compounds, their conformational preference and the energetic ordering of their conformers are determined at the MP2 and B3LYP levels of theory. Energetic barriers resulting from the interconversion between conformations are also estimated. The natural bond orbital (NBO) and interacting quantum atoms (IQA) methods are used to study fundamental intramolecular energetic effects influencing the stability of individual conformers. The results of the two methods indicate the great significance of the effect associated with electron delocalization (in the form of either NBO donor-acceptor interactions or the IQA interatomic exchange-correlation interaction energy) in governing the conformational behavior of the investigated diheteroaryl ketones and thioketones.

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“…Previous experiments in the gas phase, by microwave spectroscopy 4 and infrared in supersonic jet expansion, 3 and in solutions [5][6][7] as well as theoretical investigations 3,5,8 showed that P2C adopts the conformation where the N-C-CdO dihedral angle is in the cis orientation ( Figure 1). The trans conformer has a high relative energy, and its equilibrium population at room temperature was estimated to be very low, ,1%.…”

Section: Introductionmentioning

confidence: 95%

Infrared Spectra and Photochemistry of Matrix-Isolated Pyrrole-2-carbaldehyde

2010

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Monomeric pyrrole-2-carbaldehyde (P2C) was isolated in low-temperature argon and xenon matrices, and its UV-induced photochemistry was studied. The structures of the reagent as well as the reaction photoproducts were characterized by FTIR spectroscopy. Interpretation of the experimental results was assisted by theoretical calculations carried out at the MP2 and DFT (B3LYP) levels with the 6-311++G(d,p) basis set. The compound can assume two conformations, cis and trans, regarding the orientation of the N-C-C=O dihedral angle. The cis form is the conformational ground state, being more stable than the trans by ca. 15 kJ mol(-1). The relative stability of the two conformers was analyzed based on the comparison of their structures and using the natural bond orbital method. In agreement with the calculations, only the signature of the cis conformer was found in the experimental FTIR spectra of matrix-isolated P2C monomers. UV irradiation (lambda > 235 nm) readily converts the cis-P2C into the trans-P2C form, and a photostationary equilibrium is established where the [cis]/[trans] ratio is ca. 3.3:1 in both Ar and Xe. Upon prolonged irradiation, P2C slowly undergoes photolysis to [pyrrole + CO]. In matrices, pyrrole and CO form associates of different geometry, which could be characterized based on their vibrational signatures.

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Infrared, Density-Functional Theory, and Atoms in Molecules Method Studies on Conformers of Some 2-Substituted 1H-Pyrroles

Cited by 25 publications

References 40 publications

Can 2‐acylpyrroles form an intramolecular hydrogen bond?

Can 2‐acylpyrroles form an intramolecular hydrogen bond?

Conformers of diheteroaryl ketones and thioketones: a quantum chemical study of their properties and fundamental intramolecular energetic effects

Infrared Spectra and Photochemistry of Matrix-Isolated Pyrrole-2-carbaldehyde

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