Carbon rings: a DFT study on geometry, aromaticity, intermolecular carbon–carbon interactions and stability

Abstract

Strong complimentary electrostatic interactions lead to large number of C⋯C interactions in doubly antiaromatic C4N dimers while the delocalized system of π electrons in doubly aromatic C4N+2 dimers suggest very few intermolecular C⋯C interactions.

Induced magnetic field in sp-hybridized carbon rings: analysis of double aromaticity and antiaromaticity in cyclo[2N]carbon allotropes

“…The main question that evolved to a controversy by conflicting theoretical studies was on the bonding pattern of C 18 : is it polyynic with altering triple and single bonds, or cumulenic with equal bond lengths? Pure and hybrid DFT [19][20][21] as well as MP2 22,23 calculations predict cumulenic structures, whereas HF, 14,24 quantum Monte Carlo 25 and CCSD 26 calculations predict polyynic geometries. Further studies diagnosed that the DFT calculated bonding pattern depends on the amount of HF exchange of the hybrid functional, 27,28 whereas range-separated exchange nonempirical DFT schemes provide polyynic structures regardless of the type of functional that is used.…”

A DFT study on 1,4‐dihydro‐1,4‐azaborinine annulated linear polyacenes: Absorption spectra, singlet‐triplet energy gap, aromaticity, and HOMO–LUMO energy modulation

“…A previous benchmark study by Remya and Suresh on a variety of non‐covalent dimers using around 380 different DFT methods yielded M06L as the most reliable for geometry and interaction energy close to the CCSD(T) level accuracy. Recent studies conducted with M06L functional (the meta‐GGA local functional with 0% Hartree–Fock exchange) on a variety of systems have given reliable results in agreement with high accuracy ab initio methods and dispersion‐corrected DFT methods . The wavefunction generated at M06L/6–311++G(d,p) is used for molecular electrostatic potential (MESP) calculation.…”

“…Recent studies conducted with M06L functional (the meta-GGA local functional with 0% Hartree-Fock exchange [50] ) on a variety of systems have given reliable results in agreement with high accuracy ab initio methods and dispersion-corrected DFT methods. [51][52][53] The wavefunction generated at M06L/6-31111G(d,p) is used for molecular electrostatic potential (MESP) calculation. For all the molecules, aromaticity of each ring is quantified by computing the z component of the nucleus independent chemical shift at 1 Å above the ring centre (NICS(1) zz ).…”

Electronic effect of β‐diketonato ligands on the redox potential of fac and mer tris(β‐diketonato) iron(III) complexes: A density functional theory study and molecular electrostatic potential analysis

“…The MESP analysis is an important method that has been used to understand several chemical phenomena, such as intermolecular interactions, and various chemical properties, such as bonding, chemical reactivity, inductive effect, and resonance. In addition to the application of MESP analysis to study various chemical properties, it has also been used to predict the reduction potential of compounds …”

“…The two technically slightly different free energy cycles 1 and 2, as shown in Figure 2, are used for the calculation of the reduction potential of the complexes. In addition, the electron affinity (EA) and molecular electrostatic potential (MESP) of the tris(β-diketonato)iron(III) complexes are presented on a quantum chemistry level, to obtain better insight into the observed experimental redox behavior of complexes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] ( Figure 1).…”