Synthesis, Electrochemistry, Photophysics, and Photochemistry of a Discrete Tetranuclear Copper(I) Sulfido Cluster

Abstract

A tetranuclear copper­(I) complex, [Cu4{μ-(Ph2P)2NH}4(μ4-S)]­(PF6)2 (1), was synthesized. It was found to display intense and long-lived phosphorescence in the solid and solution states. The lowest-energy excited state was assigned as ligand-to-metal charge transfer (LMCT) [S2– → Cu4] mixed with some metal-centered (ds/dp) character. In addition, the phosphorescent state of this complex was found to be quenched by pyridinium acceptors via an oxidative electron-transfer quenching process. An excited-state reduction potential of −1.74 V versus saturated salt calomel electrode was estimated through oxidative quenching studies with a series of structurally related pyridinium acceptors, indicative of its strong reducing power in the excited state. From the transient absorption difference spectrum of the tetranuclear copper­(I) sulfido complex and 4-(methoxycarbonyl)-N-methylpyridinium hexafluorophosphate, in addition to the characteristic absorption of the pyridinyl radical at ca. 395 nm, two absorption bands at ca. 500 and 660 nm were also observed. The former was assigned as an LMCT absorption [S2– → Cu4] and the latter as an intervalence charge-transfer transition, associated with the mixed-valence species CuI/CuI/CuI/CuII.

Ionic Liquids-Driven Cluster-to-Cluster Conversion of Polyhydrido Copper(I) Clusters Cu7H5 to Cu8H6 and Cu12H9

“…The higher-energy absorptions below 350 nm are typical for ligand-centered [π → π*] (dppy ligand) absorption, based on the similar absorption energies with those of the free dppy ligand. The lower-energy shoulder is similar to that observed in the related Cu 3 H and Cu 4 H , ,− suggesting their origin from ligand-to-metal-metal charge transfer (LMMCT) or cluster-centered (CC).…”

“…Comparing the emissions both in the solid state and in solution, a red shift in energy is observed on going from Cu 7 H 5 to Cu 8 H 6 and Cu 12 H 9 (Figure S13), which is consistent with the order of the stronger cuprophilic interactions by single-crystal X-ray analysis. Following previous assignments ,− and in view of the good σ-donating capability of the dppy ligand, the origin of the emissions for three Cu­(I)H clusters is assigned as the triplet ligand-to-metal-metal charge-transfer ( 3 LMMCT) excited state or cluster-centered (CC) modified by metal–metal interactions. The red shift in the emission wavelengths of Cu 7 H 5 to Cu 8 H 6 and Cu 12 H 9 may be ascribed to the stronger cuprophilic interactions, which decreases the energy of the metal-centered acceptor orbitals and gives rise to a lower LMMCT or CC emission energy.…”

Halide-bridged tetranuclear organocopper(i) clusters supported by indolyl-based NCN pincer ligands and their catalytic activities towards the hydrophosphination of alkenes

“…Due to the diverse structures and potential applications, Cu(I) clusters have received extensive attention in the past few decades. [1][2][3][4][5][6][7][8][9][10] The structures and properties of Cu(I) clusters can be tuned by changing the supporting ligands, and multidentate-ligand-coordinated metal clusters exhibit higher stability with enhanced properties compared with monodentate-ligandcoordinated metal clusters. 11,12 A pincer-type ligand is a kind of special multidentate ligand, with advantages of the formation of the desired complexes through the designed coordination mode and strong bonds between the ligand and the central metal, therefore making the complexes exhibit good thermal stability.…”

Synthesis and Characterization of Luminescent Binuclear μ‐HS Cu(I) Complexes

“…Owing to the abundant coordination modes of the S-donor ligands, some multinuclear Cu(I) molecular architectures have been constructed with interesting photoluminescence. [32][33][34][35][36][37] Herein, we reported the synthesis, characterization and physical properties of (POP) 2 Cu 2 (μ-HS/ Cl) 2 • 0.92MeOH (1) and (POP) 2 Cu 2 (μ-HS) 2 (2).…”