Sequential metalation of benzene: electronic, bonding, magnetotropic and spectroscopic properties of coinage metalated benzenes studied by DFT

Abstract

A series of coinage metalated benzenes formulated as C6H6-nMn (M = Cu, Ag, Au, n = 1-5) were investigated by means of density functional theory (DFT) calculations. The structural, energetic, magnetotropic and spectroscopic properties of the coinage metalated benzenes were analyzed thoroughly and compared to the respective properties of the archetype aromatic benzene molecule. In contrast to the latter, the C6H6-nMn (M = Cu, Ag, Au, n = 1-5) molecules are predicted to be aromatic even in their excited triplet state. Excellent linear correlations between (I) the zz component of the nucleus independent chemical shift [NICSzz(1)] values and the total negative natural charge acquired by the carbocyclic ring, and (ii) the NICSzz(1) vs wavelength (λ) of the HOMO → LUMO transitions in the absorption spectra of the coinage metalated benzenes were established. The emission spectra of the coinage metalated benzenes were characterized by high [Formula: see text] values, particularly for the di-substituted - and p-isomers, with the highest [Formula: see text] value of 67 kcal mol(-1) calculated for the m-M6H4Au2 species. The bonding pattern of the coinage metalated benzenes was analyzed thoroughly by means of a multitude of electronic structure calculation methods [natural bond orbital (NBO), atoms-in-molecules (AIM), electron localization function (ELF), reduced density gradient (RDG) and Sign(λ 2(r))ρ(r) functions]. Our findings indicate whole classes of new coinage metalated benzenes (mono-, di-, tri-, four- and five-substituted) opening a new chemistry for the coinage metalated benzenes, indicating that their chemistry will be worthwhile studying both experimentally and theoretically in the future. Graphical Abstract The complete series of coinage metalated benzenes were investigated by density functional theory methods. The structural, energetic, bonding, magnetotropic and spectroscopic properties of the coinage metalated benzenes were analyzed thoroughly. In contrast to the archetype aromatic benzene molecule, the coinage metalated benzenes are predicted to be aromatic even in their excited triplet state.

Zwitterionic Bergman cyclization triggered polymerization gives access to metal-graphene nanoribbons using a boron metal couple

“…17). As reported by several groups, the transition metals, in these cases too, cause a more significant decrease in the energy of LUMO compared to the increase in the HOMO energy [66][67][68][69][70] . The comparison of the bandgaps in unsubstituted anthracene (3.6 eV), Au(I)-anthracene (2.6 eV), and Cu(I)-anthracene (2.0 eV) further highlights this effect (Fig.…”

Dissecting Transmetalation Reactions at the Molecular Level: Phenyl Transfer in Metal Borate Complexes

“…The calculated Ph – affinity of [Ag­(BPh 4 )] significantly exceeds that of [Li­(BPh 4 )] (383 vs 256 kJ mol –1 ; Figure S7 and Table S1), which explains why the transmetalation to silver is energetically more favorable than that to lithium. A similar trend can be discerned for the Ph – affinities of the simple Ag + and Li + cations (849 vs 670 kJ mol –1 ; Table S1), in line with the results of a recent theoretical study . As Tsipis and Gkarbounis pointed out, the higher Ph – affinity of Ag + can be attributed to the more covalent bond character of PhAg, which stabilizes it in comparison to the more ionic PhLi .…”

“…A similar trend can be discerned for the Ph − affinities of the simple Ag + and Li + cations (849 vs 670 kJ mol −1 ; Table S1), in line with the results of a recent theoretical study. 19 As Tsipis and Gkarbounis pointed out, the higher Ph − affinity of Ag + can be attributed to the more covalent bond character of PhAg, which stabilizes it in comparison to the more ionic PhLi. 19 These results are also fully in accordance with the HSAB concept, which predicts the soft Lewis base Ph − to interact more strongly with the softer Lewis acid Ag + than with the harder Lewis acid Li + .…”

“…19 As Tsipis and Gkarbounis pointed out, the higher Ph − affinity of Ag + can be attributed to the more covalent bond character of PhAg, which stabilizes it in comparison to the more ionic PhLi. 19 These results are also fully in accordance with the HSAB concept, which predicts the soft Lewis base Ph − to interact more strongly with the softer Lewis acid Ag + than with the harder Lewis acid Li + . 20 The absolute height of the fragmentation barriers is controlled by the stability of the [M(BPh 4 ) 2 ] − complexes.…”

Excited states of aurocarbons: CASPT2 and CCSD(T) calculations of C2Au2 and C2Au4

“…Investigations of electronic excited states of aurocarbons are scarce. Related to the present research is a combined experimental–theoretical work on luminescence of gold acetylides [11, 21] and DFT calculations of Tsipis and Gkarbounis on aromatic aurocarbons up to C 6 Au 6 [14, 22]. Closely related to our work is the photoelectron spectroscopy combined with DFT calculations on a series of anionic and neutral Au–(CC) n –Au auropolyynes [20] and on mixed hydrogen–gold acetylide species, including C 2 Au 2 and its anion [23].…”