An Efficient Synthesis of [n]Cycloparaphenylenes (n = 9, 12, 15) via the Self-Assembly into Macrocyclic Gold(I)-Oligophenylene Complexes Based on Dynamic Au–C σ-Bonds

The transmetalation of the digold(I) complex [Au2Cl2(Cy2PCH2PCy2)] with oligophenylene diboronic acids gave the triangu-lar macrocyclic complexes [Au2(C6H4)x(Cy2PCH2PCy2)]3 (x = 3, 4, 5) with yields of over 70%. A series of [n]cycloparaphenylenes (n = 9, 12, 15) was isolated in 78–88% yield via the oxidative chlorination of the macrocyclic gold complexes. A kinetics study employing two acyclic dinuclear gold(I) complexes, [Au2R2(Cy2PCH2PCy2)] (R = Ph and/or C6H4-4-F), revealed that an intermolecular Au(I)–C σ-bond-exchange reaction proceeded. These results indicate that the trian-gular complexes were obtained selectively via reversible intermolecular Au(I)–C σ-bond exchanges. By reacting two different oligophenylene diboronic acids with the digold(I) complex, a mixture of macrocyclic complexes incorporating different oli-gophenylene linkers was formed. The oxidative chlorination of this mixture gave [n]cycloparaphenylenes with various num-bers of phenylene units.