Aromaticity of monosubstituted derivatives of benzene. The application of out-of-plane ring deformation energy for a quantitative description of aromaticity

Шишкин, Олег В.; Omelchenko, Irina V.; Krasovska, Marina; Zubatyuk, Roman I.; Gorb, Leonid; Leszczyński, Jerzy

doi:10.1016/j.molstruc.2006.01.019

Cited by 34 publications

(45 citation statements)

References 41 publications

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“…Applying the out-of-plane ring deformation energy aromaticity criterion proposed by Shishkin et al 55 we found that the outof-plane deformation energy ! 3 of the 3-membered aromatic metal rings correlates well with NICS (1) (Fig.…”

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confidence: 99%

Growth format, electronic architecture, magnetic, and optical properties of aromatic cyclo‐Cu₃Au₃ homotops

Tsipis¹,

Depastas²,

Kefalidis³

2007

J Comput Chem

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Bimetallic Cu(3)Au(3) clusters have been investigated using electronic structure calculation techniques (DFT) to understand their electronic, magnetic, and optical properties as well as the geometrical structures. The most stable homotop is the planar cyclo-[Cu(3)(micro-Au)(3)] form consisting of a triangular positively charged Cu(3) structural core with negatively charged Au atoms occupying exposed positions. This structure is characterized by the maximum number of heterobonds and peripheral positions of Au atoms. Possible growth formats of the cyclo-[Cu(3)(micro-Au)(3)] homotops have been explored following both the edge-capping and the stepwise metal atom substitution mechanism. The bonding pattern along with the density of states (DOS) plots of the cyclo-[Cu(3)(micro-Au)(3)] homotop are thoroughly analyzed and compared with those of the pure cyclo-[Cu(3)(micro-Cu)(3)] and cyclo-[Au(3)(micro-Au)(3)] clusters. Particular attention was paid on the stability of these bimetallic clusters in relation with the ring-shaped electron density distribution (aromaticity). It was found that all 3-membered metal rings exhibit significant aromatic character, which was verified by a number of established criteria of aromaticity, such as structural, energetic, magnetic (NICS profiles), and out-of-plane ring deformability criteria. The NICS (1) values correlate well with the out-of-plane ring deformation energy. Finally, a comprehensive analysis of the optical spectra of the CuAu, Cu(2), and Au(2) diatomics and the cyclo-[Cu(3)(micro-Au)(3)], cyclo-[Cu(3)(micro-Cu)(3)], and cyclo-[Au(3)(micro-Au)(3)] clusters placed the electronic assignments of the optical transitions on a firm footing.

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mentioning

confidence: 99%

Growth format, electronic architecture, magnetic, and optical properties of aromatic cyclo‐Cu₃Au₃ homotops

Tsipis¹,

Depastas²,

Kefalidis³

2007

J Comput Chem

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“…Barriers for interconversion between minimum energy conformers are found to be low, which indicates the possibility of quite easy transitions from planar to non-planar structures. Therefore, 1,3-disubstituted azulenes are expected to undergo out-of-plane deformations with negligible energy requirements, despite their aromatic character [11][12][13][14][15]. Among compounds under study, compound 3 has the highest interconversion barrier, which in turn can be related to a larger conjugation between substituents and the p-system of the azulene core compared to compounds 1 With the aim of getting insights into the origin of out-ofplane deformations found in 1,3-disubstituted azulenes, the aromaticity of these compounds has been analyzed by means of three aromaticity indicators that account for geometric, magnetic, and energetic aspects of aromaticity: (a) the Harmonic oscillator model of aromaticity index (HOMA) [24][25][26]; (b) Nucleus-independent chemical shifts (NICS); and (c) the frequency of the lowest out-of-plane vibration m min (cm -1 ).…”

Section: Resultsmentioning

confidence: 99%

“…The frequency of the lowest out-of-plane vibration m min (cm -1 ) was employed as an energetic aromaticity criterion [11][12][13][14][15]. This indicator was obtained directly from the vibrational analysis performed on minimum energy structures of azulenes under study.…”

Section: Planarity Index Pmentioning

confidence: 99%

“…Numerous studies reported this kind of deformations on benzenoid compounds, showing that these rings possess a notable degree of conformational flexibility, despite their aromatic character [11][12][13][14][15]. However, there are few studies on out-of-plane deformations for non-benzenoid compounds, particularly in the case of azulene derivatives.…”

Section: Introductionmentioning

confidence: 99%

“…Relative energies and interconversion barriers were employed to analyze the transition from planar to non-planar structures. Additionally, the aromatic character of each minimum energy conformation was evaluated by aromaticity indicators, such as the Harmonic Oscillator Model of Aromaticity index (HOMA) [24][25][26], Nucleus Independent Chemical Shifts (NICS) [24,25], and the frequency of the lowest out-ofplane vibration [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Theoretical approach to the out-of-plane deformation of 1,3-disubstituted azulenes

Jiménez

2009

Struct Chem

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Computational calculations at B3LYP/6-311??G(d,p) and MP2/6-311??G(d,p) levels were employed to analyze the structure and conformation of 1,3-bis(4-bromophenyl)azulene (1), 1,3-bis(2-thienyl)azulene (2), and 1,3-bis(2-pyrrollyl)azulene (3) in order to rationalize the out-of-plane deformation found in the azulene cores of 1 and 2 in the crystalline state, whereas compound 3 shows a totally planar azulene moiety. Our results indicate that 1,3-disubstituted azulenes possess two almost equally stable and easily convertible minimum energy conformers, which differ in the relative orientation of the substituent groups and in the planarity degree of the azulene core. An absolute planarity index (P) is introduced to quantify the out-of-plane distortion found in the azulenes under study. The aromaticity of minimum energy conformers was evaluated by means of geometric (HOMA), magnetic (NICS), and energetic (the frequency of the lowest out-of-plane vibration, m min ) aromaticity indicators, which suggest that compound 3 possesses the most aromatic azulene core within the group. Calculated molecular dipole moments suggest that the conformation of 1,3-disubstituted azulenes in the crystalline state can be explained in terms of electrostatic intermolecular interactions rather than relative stability of planar and non-planar conformers.

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The fractal and scaling analysis of chemical reactions

Козлов

Шустов

Заиков

2004

J of Applied Polymer Sci

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It is shown that the geometrical factor controlling a thermooxidative degradation course is effective spectral dimension dЈ s or factor ␤. In turn, parameters dЈ s and ␤ are a function of a polymer melt structure characterized by its fractal dimension ⌬ f . The applicability of this or that scaling relationship allows the evaluation of general features of chemical reactions in the thermooxidative degradation process.

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Aromaticity of monosubstituted derivatives of benzene. The application of out-of-plane ring deformation energy for a quantitative description of aromaticity

Cited by 34 publications

References 41 publications

Growth format, electronic architecture, magnetic, and optical properties of aromatic cyclo‐Cu₃Au₃ homotops

Growth format, electronic architecture, magnetic, and optical properties of aromatic cyclo‐Cu₃Au₃ homotops

Theoretical approach to the out-of-plane deformation of 1,3-disubstituted azulenes

The fractal and scaling analysis of chemical reactions

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Aromaticity of monosubstituted derivatives of benzene. The application of out-of-plane ring deformation energy for a quantitative description of aromaticity

Cited by 34 publications

References 41 publications

Growth format, electronic architecture, magnetic, and optical properties of aromatic cyclo‐Cu3Au3 homotops

Growth format, electronic architecture, magnetic, and optical properties of aromatic cyclo‐Cu3Au3 homotops

Theoretical approach to the out-of-plane deformation of 1,3-disubstituted azulenes

The fractal and scaling analysis of chemical reactions

Contact Info

Product

Resources

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Growth format, electronic architecture, magnetic, and optical properties of aromatic cyclo‐Cu₃Au₃ homotops

Growth format, electronic architecture, magnetic, and optical properties of aromatic cyclo‐Cu₃Au₃ homotops