Probing hyperconjugative aromaticity in 2H-pyrrolium and cyclopentadiene containing group 9 transition metal substituents: bridged carbonyl ligands can enhance aromaticity

Abstract

Bridged carbonyls can enhance hyperconjugative aromaticity of group 9 transition metal disubstituted 2H-pyrrolium and cyclopentadiene.

Probing the Hyperconjugative Aromaticity of Cyclopentadiene and Pyrroliums Containing Group 7 Transition Metal Substituents

“…Previous studies suggested that the metal−metal bonding interaction reduces aromaticity, whereas the bridged carbonyls enhance aromaticity. 52 To further explore the interaction between hyperconjugative aromaticity and transition metal substituents, species 1−16 are designed based on the experimental structures (μ-H)(μ-P(C 6 H 11 ) 2 ) (CO) 8 Mn 2 , [(CO) 4 Mn = Mn(CO) 4 ] 2− , (η 5 -C 5 Me 5 ) 2 Mn 2 (μ-CO) 3 , 84−86 and C 31 H 50 N 4 ORe 2 78 (Figure 4). Among them, the effect of bridged ligands (e.g., μ-O, μ-NH, μ-BH, μ-CO, and μ-H − ) and ligands (e.g., H − and F − ) were explored in Mn−Mn single bond systems.…”

“…51 In the same year, the Zhu group reported the hyperconjugative aromaticity in 2H-pyrrolium and cyclopentadiene containing group 9 transition metal substituents, in which bridged carbonyl ligands could increase the aromaticity. 52 The substituents containing groups 9, 10, and 11 transition metals could induce the hyperconjugative aromaticity of cyclopentadienes, pyrroliums, and indoliums in previous studies. We hypothesized that hyperconjugative aromaticity might be also achieved in group 7 transition metal disubstituted complexes.…”

“…Recently, the Zhu group investigated theoretically the hyperconjugative aromaticity of indoliums containing Au­(III) substituents by tuning the ligand or cis–trans isomerization . In the same year, the Zhu group reported the hyperconjugative aromaticity in 2 H -pyrrolium and cyclopentadiene containing group 9 transition metal substituents, in which bridged carbonyl ligands could increase the aromaticity …”

Structure-property relationships of photofunctional diiridium(II) complexes with tetracationic charge and an unsupported Ir–Ir bond

“…This result is in agreement with other previous computational studies suggesting the importance of London dispersion in some metal complexes [74][75][76][77][78][79][80][81] . As shown in Supplementary Table S14, both metal-metal 82 and non-covalent interactions among the tridentate pincer ligands and counterions should be generally the critical factors in stabilizing the rare Ir(II)-Ir(II) bond and rendering the unusually large binding energies for tetracationic complexes 1-3 by conquering unfavorable and strong electrostatic repulsions.…”

Screening Carbon‐Boron Frustrated Lewis Pairs for Small‐Molecule Activation including N2, O2, CO, CO2, CS2, H2O and CH4: A Computational Study

“…NICS was suggested by Schleyer and coworkers and the reliability of NICS has been supported by several studies. [50][51] The NICS(1) zz value describes the zz component at 1 Å above the geometric center of the ring, which is recommended to evaluate the aromaticity in both the lowest singlet and triplet states. [52] As shown in Figure 4, for the aromaticity of FLP, the NICS(1) zz values of rings A and B are À 22.0 and À 3.0 ppm, respectively, indicating the aromatic ring A and nonaromatic ring B.…”