Organometallic chemistry at the edge of polycyclic aromatic hydrocarbons

Zirconocene and bisphosphine nickel chemistry developed in our labs and directed towards the derivatization and synthesis of polycyclic aromatic carbon compounds is reviewed. Complexes with the formula Cp2ZrMe(η1-PAC) (PAC=anionic polycyclic aromatic carbon ligand) eliminate methane to produce zirconacycles and yne complexes. Treatment of the zirconacycles with L2NiX2 (L=phosphine, X=Cl, Br) in the presence of alkynes results in metallacycle transfer to nickel and cycloaddition of the alkyne. The resulting polycyclic aromatic carbon compounds contain an additional ring. The nickelacycles may also be accessed by oxidative addition of Ni(0) to polycyclic aromatic dihalides followed by reduction. The application of this chemistry to the step-growth synthesis of single-walled carbon nanotubes is proposed.