Jailbreaking Benzene Dimers

Abstract

We suggest four new benzene dimers, (C(6)H(6))(2), all featuring one or more cyclohexadiene rings trans-fused to 4- or 6-membered rings. These hypothetical dimers are 50-99 kcal/mol less stable than two benzenes, but have computed activation energies to fragmentation ≥27 kcal/mol. A thorough search of potential escape routes was undertaken, through cyclobutane ring cleavage to 12-annulenes, sigmatropic 1,5-H-shifts, electrocyclic ring-openings of the 6-membered rings, and Diels-Alder dimerizations. Some channels for reaction emerge, but there is a reasonable chance that some of these new benzene dimers can be made.

Communication: Benzene dimer—The free energy landscape

“…The benzene dimer represents the archetypal system for aromatic interactions that have been implicated in diverse phenomena ranging from stabilization of protein structures, DNA base-pair stacking, tertiary structure of proteins, controlling the intercalation of drugs into DNA, encapsulation of linear carbon chain molecules inside single-walled carbon nanotubes, molecular recognition process in biological and artificial systems, and benzene dimerization that has been implicated in soot formation. [1][2][3][4][5][6][7] In addition, the benzene dimer has become the benchmark system for electronic structure methods for systems where dispersion interactions are important. It is, therefore, not surprising that the structure of the gas-phase benzene dimer has received considerable attention from both experimentalist and theoreticians.…”

Mechanistic Details of Pd(II)-Catalyzed C–H Iodination with Molecular I2: Oxidative Addition vs Electrophilic Cleavage

“…The structural features of these complexes are in full agreement with nature of the iodine molecule and recent analysisof [d 8 -Pt(II)]-I 2 bonding byRogachev and Hoffmann. 48 Briefly, the I 2 molecule, with the frontier electronic configuration of[ … (1σ g ) 2 (1σ u * ) 2 (2σ g ) 2 (2π u ) 4 (2π g * ) 4 (2σ u * ) 0 ], can function either as anelectron acceptor (to the 2σ u * orbital)or an electron donor(from the2π g * orbital). As an electron accepting ligand,the 2σ u * orbital of I 2 preferably interacts with thedoubly occupied݀ ௭ మ orbital of Pd.…”

Pressure‐Induced Diels–Alder Reactions in C6H6‐C6F6 Cocrystal towards Graphane Structure

“…In contrast, aseries of dimers (C 12 H 6 F 6 ), trimers (C 18 H 6 F 12 and C 18 H 12 F 6 ), and tetramers (C 24 H 12 F 12 )were identified, and highlights the addition between benzene and hexafluorobenzene.A ss hown in Figure 4a,i ti sn otable that the C 24 H 12 F 12 tetramer has am uch higher content when synthesized under higher pressure (PE20), and has the second highest percentage in total. Therefore,i ti sr easonable to infer that the addition reaction is the pathway to synthesize the CHCF polymer.I nt he MS of the tetramer C 24 H 12 F 12 ,t he fragments C 6 (Figure 4b). This indicates the tetramers have an alternate connection, such as C 6 H 6 -C 6 F 6 -C 6 H 6 -C 6 F 6 .C onsidering the [4+ +2] Diels-Alder reaction determined from the IR result, the PIP of C 6 H 6 and C 6 F 6 is most likely ap rocess of serial [4+ +2] Diels-Alder reactions.W ea lso identified as ignificant amount of 1,2,3,4-tetrafluoronaphthalene in the GC-MS result, and it probably comes from the following reaction process.T he product of the Diels-Alder reaction undergoes aretro-Diels Alder reaction to eliminate aC 2 (H,F) 2 molecule with subsequent elimination of two F/H species (Scheme 1a).…”

“…[2d] Besides the one-dimensional structure, the graphane structure was also obtained by compressing the aromatics under high-pressure and high-temperature conditions. [5,6] Experimentally,apossible reaction route including a[4+ +2] cycloaddition reaction followed by an intramolecular "zipper" cascade reaction, was proposed according to the p-p stacking of the benzene molecules and the structural model of the product. Va rious possible connections between benzene molecules were theoretically proposed, and the energies of the formed dimers were examined to evaluate the corresponding reactions.…”

“…Va rious possible connections between benzene molecules were theoretically proposed, and the energies of the formed dimers were examined to evaluate the corresponding reactions. [5,6] Experimentally,apossible reaction route including a[4+ +2] cycloaddition reaction followed by an intramolecular "zipper" cascade reaction, was proposed according to the p-p stacking of the benzene molecules and the structural model of the product. [2a] All of these reports suggest the reaction starts from the bonding between the p-p stacked aromatics.…”