Highly Luminescent Linear Complex Arrays of up to Eight Cuprous Centers

Linearly arranged metal atoms that are embedded in discrete molecules have fascinated scientists across various disciplines for decades; this is attributed to their potential use in microelectronic devices on a submicroscopic scale. Luminescent oligonuclear Group 11 metal complexes are of particular interest for applications in molecular light-emitting devices. Herein, we describe the synthesis and characterization of a rare, homoleptic, and neutral linearly arranged tetranuclear CuIcomplex that is helically bent, thus representing a molecular coil in the solid state. This tetracuprous arrangement dimerizes into a unique octanuclear assembly bearing a linear array of six CuI centers with two additional bridging cuprous ions that constitute a central pseudo-rhombic CuI4 cluster. The crystal structure determinations of both complexes reveal close d10⋅⋅⋅d10 contacts between all cuprous ions that are adjacent to each other. The dynamic behavior in solution, DFT calculations, and the luminescence properties of these remarkable complexes are also discussed

A New Dimension in Cyclic Coinage Metal Pyrazolates: Decoration with a Second Ring of Coinage Metals by Inter-ring Metallophilic Interactions

When pyrazolate ligands with thioether chelate arms are used in cyclic coinage metal pyrazolates [Au(μ-pz)]n, the inner gold ring can be framed with an outer silver ring to give novel heterometallic double-crowned complexes [AuAg(μ-Lx)(BF4)]4. They feature short intramolecular in-plane Ag–Au interactions, are stable as octanuclear species in solution, and show promising luminescence properties

Remarkable stability of copper(II)-N-heterocyclic carbene complexes void of an anionic tether

A library of pyridyl- and picolyl-substituted imidazolium salts have been synthesized and coordinated to copper, via transmetalation from silver(I)-N-heterocyclic carbenes (NHCs), to prepare several copper(I)- and copper(II)-NHC complexes. The copper(I)-NHCs are complexes of the type Cu(NHC)Br, with the solid-state structures revealing a variety of coordination environments around the copper centers. The stability of the copper(II) complexes is particularly unusual, given the absence of a "hard" anionic tethering group appended to the ligands. The stability has been attributed to the pyridyl substituent, with the complexes being extremely stable, while those with an appended anionic group tend to be more sensitive to air/moisture. The ligands and complexes have been examined in an Ullmann-type etherification reaction and exhibit improved activity in comparison to copper in the absence of a ligand or the common Cu(I)-NHC complexes Cu(IMes)Cl and [Cu(IMes)2]PF6, indicating stabilization of higher oxidation state species by the ligands during the catalytic cycle