A merged copper(I/II) cluster isolated from Glaser coupling

Abstract

Ubiquitous copper-oxygen species are pivotal in enabling multifarious oxidation reactions in biological and chemical transformations. We herein construct a macrocycle-protected mixed-valence cluster [(tBuC≡CCuI3)-(μ2-OH)-CuII] by merging a copper acetylide cluster with a copper-oxygen moiety formed in Glaser coupling. This merged Cu(I/II) cluster shows remarkably strong oxidation capacity, whose reduction potential is among the most positive for Cu(II) and even comparable with some Cu(III) species. Consequently, the cluster exhibits high hydrogen atom transfer (HAT) reactivity with inert hydrocarbons. In contrast, the degraded [CuII-(μ2-OH)-CuII] embedded in a small macrocyclic homologue shows no HAT reactivity. Theoretical calculations indicate that the strong oxidation ability of Cu(II) in [(tBuC≡CCuI3)-(μ2-OH)-CuII] is mainly ascribed to the uneven charge distribution of Cu(I) ions in the tBuC≡CCuI3 unit because of significant [dCu(I) → π*(C≡C)] back donation. The present study on in situ formed metal clusters opens a broad prospect for mechanistic studies of Cu-based catalytic reactions.

Self-assembly of a Mixed Valence Copper Triangular Prism and Transformation to Cage Triggered by an External Stimulus

“…To confirm the oxidation of the copper centers in the prism 1 , the XPS spectrum of prism 1 was measured. As shown in Figure b, the spectrum of prism 1 showed a strong asymmetric Cu 2p 3/2 photoelectron peak with satellite peaks, indicating the mixed valence characteristic of the copper center in prism 1 . The Cu 2p 3/2 peaks can be deconvoluted into two contributions, which are located at 933.36 and 934.95 eV, respectively (Figure b), which is in good agreement with that of metallocycle Cu 6 L1 3 .…”

Dinuclear Cu(I) Halides with Terphenyl Phosphines: Synthesis, Photophysical Studies, and Catalytic Applications in CuAAC Reactions

“…In all cases, only one species was detected with calculated diffusion coefficients of ca . (6–7) × 10 –10 m 2 ·s –1 , in accord with previously reported data for complexes of similar size . Moreover, the diffusion coefficients were used to calculate the corresponding hydrodynamic radii of the molecules with the Stokes–Einstein equation giving values of ca.…”

“…(6−7) × 10 −10 m 2 •s −1 , in accord with previously reported data for complexes of similar size. 33 Moreover, the diffusion coefficients were used to calculate the corresponding hydrodynamic radii of the molecules with the Stokes−Einstein equation giving values of ca. 6−7 Å in good agreement with the equivalent radii estimated from the X-ray molecular structures of the dimers.…”

Structural and Electronic Control of the Bidentate 1‐(2‐pyridyl)benzotriazole Ligand in Copper Chemistry with Application to Catalysis in the A3 Coupling Reaction

“…Copper is a labile transition metal, plural in oxidation states, that promotes a variety of organic transformations either as a metal salt, in situ formed or well‐characterized complexes [1, 2] . In its dominant oxidation state II, the d 9 electronic configuration confers elongated or shortened axial axes, known as the Jahn–Teller effect, [3] and depending on the coordinating ligands various geometries and stereoisomers, that is, cis – trans for CuX 2 (N‐N) 2 where N‐N’ is a bidentate ligand, can be obtained.…”