Binuclear Complexes Supported by a Tetrapyridyl Ligand with a Bending Anthraquinodimethane Linker

A tetrapyridyl ligand with a bending anthraquinodimethane
linker
has been synthesized, and its complexation with coinage metals has
been examined. The treatment of the ligand with Ag(I) and Au(I) cations
afforded binuclear complexes, wherein the two metal centers were in
close proximity to the inside space of the ligand. X-ray analyses
corroborated with theoretical calculations indicated that the ligand
has reasonable flexibility toward a bending deformation of the linker
moiety to provide a ligand pocket suitable for the proximal binuclear
complexes, even though such deformations accompany a non-negligible
amount of energetic cost. On the other hand, treatment with 2 equiv
of Cu(I) salt afforded a binuclear complex, in which both copper atoms
were coordinated at the periphery of the ligand.