Chemoselective C−C σ‐Bond Activation of the Most Stable Ring in Biphenylene**

Abstract

The chemoselective cleavage of a six‐membered aromatic ring in biphenylene is reported using an aluminum(I) complex. This type of selectivity is unprecedented. In every example of transition metal mediated C−C σ‐bond activation reported to date, the reaction occurs at the central four‐membered ring of biphenylene. Insight into the origin of chemoselectivity was obtained through a detailed mechanistic analysis (isolation of an intermediate, DFT studies, activation strain analysis). In conclusion, the divergent reactivity can be attributed to differences in both the symmetry and radial extension of the frontier molecular orbitals of the aluminum(I) fragment compared to that of common transition metal fragments.

Transfer of an Aluminium Atom: An Avenue to Aluminium Heterocycles

“…It is worth noting that such dual emissive materials are still rare but are very attractive for their large scope of applications, such as the construction of cost-efficient white organic lightemitting diodes (WOLEDs). 100,101 Remarkably, in contrast to previous reports describing cycloadditions of low-valent Al species with hydrocarbons, 37,74,[77][78][79][80][81][82][83] the Al atom in compounds 2, 4 and 5 remains three-coordinate. This provides opportunities for further functionalizations.…”

“…Unlike the remarkable cycloaddition reactivity of base-stabilized aluminylenes 74,[77][78][79][80][81][82][83] and aluminyl anions, 37 we showed the inertness of 1 with naphthalene and biphenylene, which is due to the large HOMO-LUMO gap of 5.97 eV. 74 Nonetheless, 1 reacted with 2,3-dimethyl-1,3-butadiene and E, E-1,4-diphenyl-1,3-butadiene in toluene at room temperature to give [4+1] cycloaddition products 2 (80%) and 3 (72%), respectively (Figure 2).…”

Thermal and electrical transport properties of two-dimensional Dirac graphenylene: a first-principles study

“…The combination of four-membered and six-membered carbon rings makes graphenylene more stable. 40 In addition, the equivalent carbon atom C1 is located at the 1a (0.454, 0.328, 0.500) Wyckoff position. It can also be noted that graphenylene has a P 6/ mmm symmetry (space group D 1 6h ), belonging to the trigonal crystal system (optimized lattice constants are a = b = 6.761 Å and c = 20.000 Å).…”

Bonding, Structure and Uses of Metals

“…Researchers have reported 2 copper complexes supported by aluminum or gallium metallo-ligands feature two centre/one-electron σ bonds [16] . The first aluminum-aluminum double bond was reported in 2017 [17] also in a first for organo-metallic reactivity, aluminum has been found to selectively break biphenylene's strongest carbon-carbon bond while leaving sever weaker bonds intact [18] .…”