Cuprophilic Interactions in and between Molecular Entities.

Despite being weak attractive forces, closed-shell metallophilic interactions play important roles in the Group 11 metal complexes on their diverse structural and physical features. A plethora of experimental and computational studies has thus been dedicated to such weak attractive d -d interactions, particularly aurophilic and argentophilic interactions. Although d -d Cu -Cu forces had been recognized for four decades, cuprophilic interactions are less explored and they are best evidenced by single-crystal X-ray crystallographic analysis on Cu complexes and aggregates thereof, by which precise information about the Cu⋅⋅⋅Cu contacts, shorter than the sum of two van der Waals radii (3.92 Å) between the copper centers concerned can be obtained. Based on recently compelling experimental and spectroscopic evidence for intra- and intermolecular cuprophilic interactions in copper chemistry, the present Minireview summarizes recent progress in the past three decades in the synthesis and structures of multinuclear homometallic copper complexes, whereby supported and unsupported d -d Cu -Cu interactions are at work.