A theoretical study of the aromaticity in neutral and anionic borole compounds

Jiménez-Halla, J. Oscar C.; Matito, Eduard; Solà, Miquel; Braunschweig, Holger; Hörl, Christian; Krummenacher, Ivo; Wahler, Johannes

doi:10.1039/c4dt03445g

Cited by 40 publications

(19 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…12 The choice of methodology is due to its non-empirical nature, besides its good performance in the calculation of several properties in different systems. [13][14][15] The issue of assigning formal oxidation states within the molecule has been addressed using the effective oxidation state (EOS) method of Salvador and co-workers. 16 The EOS employs localized effective atomic orbitals to assign electrons to atoms, a Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU) and Donostia providing the most likely distribution of electrons as opposed to the average distribution of electrons (i.e.…”

Section: Methodsmentioning

confidence: 99%

The aromaticity of dicupra[10]annulenes

Grande‐Aztatzi

Mercero

Matito

et al. 2017

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

An extensive theoretical investigation of the electronic structure of a tested fair model dicupra[10]annulene compound, based on the analysis of atom-pair delocalization indices, Bader's molecular graph, the inspection of the canonical molecular orbitals, the z components of their Nuclear Independent Chemical Shifts, NICS(0), and the normalized Giambiagi multicenter delocalization indices, concludes that the perimeter aromaticity of the dicupra[10]annulene ring is consistent with both 10 and 14 π-electron Hückel aromatic 10-membered rings. In either case, the 10-membered ring encloses two 6 π-electron aromatic inner rings, hinged at the Cu-Cu bond. This work demonstrates that the aromaticity of dicupra[10]annulenes closely resembles that of naphthalene. Hence, they are best regarded as metalla-polyacenes, which could make the building blocks of extended structures such as metalated nanotubes.

show abstract

Section: Methodsmentioning

confidence: 99%

The aromaticity of dicupra[10]annulenes

Grande‐Aztatzi

Mercero

Matito

et al. 2017

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Both I ring and MCI are among the less fallible aromaticity indices available in the literature [2,36,45] and, therefore, they have been used in a plethora of cases involving a difficult assessment of aromaticity [46][47][48][49][50][51][52][53][54]. However, these indices present some drawbacks that prevent their use in large rings [55] and, therefore, we have recently designed [55] and tested [40,56] a new electronic aromaticity index, AV1245, based on MCI but free of the shortcomings of this index.…”

Section: Av1245 and Av Minmentioning

confidence: 99%

How do the Hückel and Baird Rules Fade away in Annulenes?

et al. 2020

Self Cite

View full text Add to dashboard Cite

Two of the most popular rules to characterize the aromaticity of molecules are those due to Hückel and Baird, which govern the aromaticity of singlet and triplet states. In this work, we study how these rules fade away as the ring structure increases and an optimal overlap between p orbitals is no longer possible due to geometrical restrictions. To this end, we study the lowest-lying singlet and triplet states of neutral annulenes with an even number of carbon atoms between four and eighteen. First of all, we analyze these rules from the Hückel molecular orbital method and, afterwards, we perform a geometry optimization of the annulenes with several density functional approximations in order to analyze the effect that the distortions from planarity produce on the aromaticity of annulenes. Finally, we analyze the performance of three density functional approximations that employ different percentages of Hartree-Fock exchange (B3LYP, CAM-B3LYP and M06-2X) and Hartree-Fock. Our results reveal that functionals with a low percentage of Hartree-Fock exchange at long ranges suffer from severe delocalization errors that result in wrong geometrical structures and the overestimation of the aromatic character of annulenes.

show abstract

“…Restricted optimization freezing the respective torsion lead to structures only 1.0 kcal mol −1 higher in energy, thus indicating very shallow potential surfaces. Weak B–Ar π→p‐interactions have also been suggested by Raman spectroscopic investigations for aryl moieties, whereas electron‐rich heteroaryls interact significantly …”

Section: Resultsmentioning

confidence: 83%

“…Weak B-Ar p!p-interactions have also been suggested by Raman spectroscopici nvestigations for aryl moieties, [92] whereas electron-richh eteroaryls interact significantly. [44,93] Absorption spectroscopy of boroles gives experimental insight into the frontier p-orbitale nergy separation. The color of boroles arises from p/p*e xcitations from the HOMO into the LUMO with usually modest absorption coefficients (e !…”

Section: Resultsmentioning

confidence: 99%

Electronic Push–Pull Modulation by Peripheral Substituents in Pentaaryl Boroles

Heitkemper

Sindlinger

2019

Chemistry A European J

View full text Add to dashboard Cite

Establishing access to a bulky tetraaryl dilithiobutadiene (Ph*C)4Li2 (Ph*=3,5‐tBu2(C6H3)) allowed for the synthesis of five‐membered heterocycles with incorporated main‐group elements. Along with an amino borole, a set of substituted pentaaryl boroles (Ph*C)4BAr has been synthesized. The examination of their absorption spectra and computational studies by means of DFT granted insight into the influence of peripheral substituents on the electronic features of the parent pentaphenyl borole (PhC)4BPh. Introduction of the more electron‐rich Ph* residue at the carbon atoms increases the HOMO energy, redshifting the visible π/π*‐absorption bands compared with the parent pentaphenyl borole. The influence on the frontier orbitals of three different boron‐bound aryls with electronically modulating substituents in the remote 3,5‐positions Ar=3,5‐R2‐C6H3 (R=Me, H, CF3) was studied. The substituents were found to increase (+I effect, Me) or decrease (−I effect, CF3) the LUMO energy, thus directly affecting the visible absorption spectra. This represents the first study on HOMO–LUMO‐gap adjustments by a combined push–pull approach of a substituted pentaphenylborole.

show abstract

A theoretical study of the aromaticity in neutral and anionic borole compounds

Cited by 40 publications

References 67 publications

The aromaticity of dicupra[10]annulenes

The aromaticity of dicupra[10]annulenes

How do the Hückel and Baird Rules Fade away in Annulenes?

Electronic Push–Pull Modulation by Peripheral Substituents in Pentaaryl Boroles

Contact Info

Product

Resources

About