Cationic Heterobimetallic Mg(Zn)/Al(Ga) Combinations for Cooperative C–F Bond Cleavage

Low-valent (MeBDI)Al and (MeBDI)Ga highly Lewis acidic cations in [(tBuBDI)M+⋅C6H6][(B(C6F5)4−] (M=Mg or Zn, MeBDI=HC[C(Me)N-DIPP]2, tBuBDI=HC[C(tBu)N-DIPP]2, DIPP=2,6-diisopropylphenyl) react to heterobimetallic [(tBuBDI)Mg–Al(MeBDI)+], [(tBuBDI)Mg–Ga(MeBDI)+] [(tBuBDI)Zn–Ga(MeBDI)+]. These feature long Mg–Al (or Ga) bonds while the Zn–Ga bond is short. The [(tBuBDI)Zn–Al(MeBDI)+] cation was not formed. Combined AIM charge calculations suggest that metal–metal Zn are considerably more covalent, whereas those Mg should be described as weak AlI(or GaI)→Mg2+ donor bonds. Failure isolate Zn–Al combination originates from cleavage of C−F solvent fluorobenzene give (tBuBDI)ZnPh (MeBDI)AlF+ which extremely observed, but (MeBDI)Al(F)-(μ-F)-(F)Al(MeBDI)+ verified by X-ray diffraction. DFT show remarkably facile C–F follows a dearomatization/rearomatization route.