Theoretical investigation on geometries and aromaticity of mixed boron-, nitrogen- and furanoxo-containing five-membered rings B2N2OHp (p=0–2)

Ren, Fangfang; Ren, Jun

doi:10.1016/j.theochem.2009.05.023

Cited by 12 publications

(4 citation statements)

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“…Due to the fact that both families of methods are largely used for the computation of thermodynamic properties of B-containing molecules, [55][56][57][58][59] research of this kind can greatly improve the reliability of calculations of such interesting systems; see, for example, BODIPY (boron-dipyrromethene; 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene). 60 It can also help to solve industrial problems involving the physics and chemistry of tautomers 61,62 and provide benchmark data.…”

Section: Discussionmentioning

confidence: 99%

“…Because the idea that “at all levels of calculations, the keto form is thermodynamically more stable than the enol form” based on G2 data was not confirmed by higher-level ab initio and DFT calculations, extra research is needed to estimate the accuracy of complex energy computation methods (e.g., G n and CBS) on other boron-containing systems. Due to the fact that both families of methods are largely used for the computation of thermodynamic properties of B-containing molecules, − research of this kind can greatly improve the reliability of calculations of such interesting systems; see, for example, BODIPY (boron-dipyrromethene; 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) . It can also help to solve industrial problems involving the physics and chemistry of tautomers , and provide benchmark data. , …”

Section: Discussionmentioning

confidence: 99%

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Boryl Substitution of Acetaldehyde Makes It an Enol: Inconsistency between Gn/CBS and Ab Initio/DFT Data

Balabin

2010

J. Phys. Chem. A

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Tautomerism, a particular case of isomerism, plays an important role in modern organic chemistry, biochemistry, medicinal chemistry, pharmacology, and molecular biology. Inconsistency between results of complex energy computation methods Gn/CBS (G2, G3, CBS-4M, and CBS-QB3) and high-level ab initio/DFT ones (CCSD(T)/CBS, MP2/CBS, and B3LYP/aug-cc-pVTZ) is found. Gn/CBS methods provide a qualitatively different description of tautomeric (keto-enol) equilibrium in 2-substituted acetaldehydes. According to valence focal point analysis (FPA) based on CCSD(T)/aug-cc-pVTZ, MP3/aug-cc-pVQZ, and MP2/aug-cc-pV5Z energies, boryl substitution of acetaldehyde makes it an enol. In other words, enol was found to be the global minimum on the potential energy surface (PES) of C(2)H(5)BO. Gn/CBS methods predict the keto form to be the minimum. The relative energy of alkenol, CH(BH(2))=CH(OH), is calculated to be -1.67 +/- 0.82 kcal mol(-1) at CCSD(T)/CBS level of theory. Hydrogen shift effects are also calculated in two other 2-substituted acetaldehydes, namely, 3-oxopropanenitrile (C(3)H(3)NO) and ethanal (C(2)H(4)O), with a general formula of XH(2)C-CHO (X = BH(2), CN, and H). Electron density (charge) transfer between the C=C double bond and the free p orbital of the boron atom (B) in a boryl group (BH(2)) greatly stabilizes enol with respect to ketone, CH(2)(BH(2))-CHO. The first known stabilization of enol in an acetaldehyde derivative, without an intramolecular hydrogen bond (H-bond), questions the accuracy of complex energy computation methods for boron-containing molecules. The possible reasons and consequences of this finding are discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Boryl Substitution of Acetaldehyde Makes It an Enol: Inconsistency between Gn/CBS and Ab Initio/DFT Data

Balabin

2010

J. Phys. Chem. A

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“…Augmented basis sets allow for a more accurate treatment of long-range interactions like those seen in extensively conjugated systems. The B3LYP/AUG-cc-pVTZ model chemistry has been used extensively in recent years to model the aromaticity and its causes. − Geometries optimized with DFT were verified with frequency analysis at the same level of theory as the optimization to assure no imaginary vibrational frequencies. Orbital population analysis was also conducted at the same level of theory.…”

Section: Methodsmentioning

confidence: 99%

Fluoromaticity: The Molecular Orbital Contributions of Fluorine Substituents to the π-Systems of Aromatic Rings

2021

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The addition of fluorine atoms to an aromatic ring brings about an additional set of π-bonding and antibonding orbitals culminating after the addition of the sixth fluorine with a new set of π-aromatic-like orbitals that affect the molecule in a way that we will refer to hereafter as "fluoromaticity". Depending on the number and position of the fluorine atoms, the contributed πorbitals can even further stabilize the ring leading to smaller bond lengths within the ring and higher resistance to addition reactions. This added ring stability partially explains the high thermostability and chemical resistance found in polymers containing fluorinated aromatics in their architecture. A similar molecular orbital effect is seen with the addition of other halogen atoms to aromatic rings, though to a much smaller degree and not resulting in the additional ring stability.

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“…The search for new and thermally stable insensitive explosives has long been a primary goal in the field of energetic materials chemistry in order to avoid the catastrophic explosions in use and meet the requirements of military applications [1][2][3][4]. Therefore, recently much attention has been paid to investigate the relationship between the sensitivity and structure of the energetic compounds [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

A B3LYP and MP2(full) theoretical investigation into explosive sensitivity upon the formation of the molecule-cation interaction between the nitro group of 3,4-dinitropyrazole and H+, Li+, Na+, Be2+ or Mg2+

Wang

Chen

et al. 2011

J Mol Model

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The explosive sensitivity upon the formation of molecule-cation interaction between the nitro group of 3,4-dinitropyrazole (DNP) and H(+), Li(+), Na(+), Be(2+) or Mg(2+) has been investigated using the B3LYP and MP2(full) methods with the 6-311++G** and 6-311++G(2df,2p) basis sets. The bond dissociation energy (BDE) of the C3-N7 trigger bond has also been discussed for the DNP monomer and the corresponding complex. The interaction between the oxygen atom of nitro group and H(+) in DNP…H(+) is partly covalent in nature. The molecule-cation interaction and bond dissociation energy of the C3-N7 trigger bond follow the order of DNP…Be(2+) > DNP…Mg(2+) > DNP…Li(+) > DNP…Na(+). Except for DNP…H(+), the increment of the trigger bond dissociation energy in comparison with the DNP monomer correlates well with the molecule-cation interaction energy, natural charge of the nitro group, electron density ρ(BCP(C3-N7)), delocalization energy E(2) and NBO charge transfer. The analyses of atoms in molecules (AIM), natural bond orbital (NBO) and electron density shifts have shown that the electron density of the nitro group shifts toward the C3-N7 trigger bond upon the formation of the molecule-cation interaction. Thus, the trigger bond is strengthened and the sensitivity of DNP is reduced.

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Theoretical investigation on geometries and aromaticity of mixed boron-, nitrogen- and furanoxo-containing five-membered rings B2N2OHp (p=0–2)

Cited by 12 publications

References 35 publications

Boryl Substitution of Acetaldehyde Makes It an Enol: Inconsistency between Gn/CBS and Ab Initio/DFT Data

Boryl Substitution of Acetaldehyde Makes It an Enol: Inconsistency between Gn/CBS and Ab Initio/DFT Data

Fluoromaticity: The Molecular Orbital Contributions of Fluorine Substituents to the π-Systems of Aromatic Rings

A B3LYP and MP2(full) theoretical investigation into explosive sensitivity upon the formation of the molecule-cation interaction between the nitro group of 3,4-dinitropyrazole and H+, Li+, Na+, Be2+ or Mg2+

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