Linear 6,6-Biazulenyl Framework Featuring Isocyanide Termini: Synthesis, Structure, Redox Behavior, Complexation, and Self-Assembly on Au(111)

摘要

The key step in accessing the title species (5), the first nonbenzenoid diisocyanobiaryl, involved an unexpected homo-coupling of a 6-bromoazulene derivative. The reversible 2e reduction of 5 was addressed electrochemically and computationally. The shifts in energies of the S_0→S_1 and S_o→S_2 transitions for a series of related 6,6'-biazulenyl derivatives correlate with the e"-donating/-withdrawing strength of their 2,2'-substituents but follow opposite trends. Species 5 adsorbs end-on (η~1) to the Au(111) surface via one of its -NC groups to form a 2-nm-thick film. In addition, bimetallic coordination of 5's -NC termini can be readily achieved.