Synthesis and Characterization of “Atlas-Sphere” Copper Nanoclusters: New Insights into the Reaction of Cu²⁺ with Thiols

Abstract

Thiolates are a widely used ligand class for the stabilization of M(0)-containing gold and silver nanoclusters. Curiously, though, very few thiolate-stabilized Cu nanoclusters are known. Herein, we report an examination of the reactivity of RSH (R = CH2CH2Ph, n-Bu, n-C12H25) with Cu 2+ under anhydrous conditions. These reactions result in formation of fluorescent "Atlas-sphere"-type copper-thiolate nanoclusters, including [Cu12(SR´)6Cl12][(Cu(R´SH))6] (2, R´ = n Bu) and [H(THF)2]2[Cu17(SR´´)6Cl13(THF)2(R´´SH)3] (3, R´´ = CH2CH2Ph), which were characterized by X-ray crystallography, ESI-MS, NMR spectroscopy, as well as XANES and EXAFS. Consistent with our X-ray crystallographic results, the edge energies of 2 and 3 suggest they are constructed exclusively with Cu(I) ions. Similarly, EXAFS of 2 and 3 reveal long Cu-Cu pathlengths, which is also consistent with their X-ray crystal structures. Given these results, as well as past work on Cu 2+ /thiol reactivity, we suggest that Cu(0) is unlikely to be formed by reaction of Cu 2+ with a thiol, and that previous reports of Cu(0)-containing nanoclusters synthesized by reaction of Cu 2+ with thiols are likely erroneous.

Reaction of N-Acetylcysteine with Cu2+: Appearance of Intermediates with High Free Radical Scavenging Activity: Implications for Anti-/Pro-Oxidant Properties of Thiols

“…Although the chemistry of thiols and particularly their interactions with copper ions have been studied for more than a century [ 18 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ], still little agreement exists on the fundamental mechanisms of the chemical processes involved. For instance, the classical problem of copper-catalyzed autoxidation of cysteine has remained a controversial issue as to the nature of catalytic species and the oxidation state of copper in such catalysts [ 29 , 35 , 36 , 40 , 42 , 47 ].…”

Thiolato Protected Copper Sulfide Cluster with the Tentative Composition Cu74S15(2-PET)45

“…Although they had different ligands and structural skeletons, it is possible to categorize them into similar core structures considered as building blocks. For example, [Cu 13 {S 2 CN n Bu 2 } 6 (acetylide) 4 ]­PF 6 , [Cu 25 H 22 (PPh 3 ) 12 ]­Cl, and [Cu 29 Cl 4 H 22 (Ph 2 phen) 12 ]Cl clusters consist of Cu 13 centered-cuboctahedral and icosahedral cores, respectively. − [Cu 28 (H) 15 (S 2 CNR) 12 ]­PF 6 and [Cu 14 H 12 (phen) 6 (PPh 3 ) 4 ]­[Cl] 2 consist of tetrahedron Cu 4 core incapsulated inside the copper cage. , Other structures having a hexacapped pseudorhombohedral Cu 14 core and a trigonal-bipyramidal [Cu 2 H 5 ] 3– core within the interior of the structure or unique “atlas-sphere” cluster have been reported. ,− The pioneering research in the group of Fenske and others established successful synthetic protocols for the preparation of metal chalcogenide clusters varying by size, composition, and structure. Moreover, a massive interest toward the field was in fact due to the availability and possibility of synthesizing atomically precise and chalcogenide-bridged copper clusters with drastically different Cu–S/Te/Se frameworks.…”

The Sulfur Rich Fluorothiophosphate Dianions [S5P2F2]2− and [S3PF]2− : Cluster and Chelation Control of P‐S Heterolysis

“…X‐ray diffraction confirmed the identity of the product as the anionic Cu 8 S 12 type cluster [N n Pr 4 ] 4 [Cu 8 (S 3 PF) 6 ] with a methanol solvate. The synthesis of the cluster presented here requires reduction of the Cu(II) to Cu(I): while many Cu 8 S 12 clusters reported previously use a Cu(I) starting material, [43–45] reduction of Cu(II) with sulfur containing ligands to form Cu(I) clusters is nonetheless known [46,47] …”

“…The synthesis of the cluster presented here requires reduction of the Cu(II) to Cu(I): while many Cu 8 S 12 clusters reported previously use a Cu(I) starting material, [43][44][45] reduction of Cu(II) with sulfur containing ligands to form Cu(I) clusters is nonetheless known. [46,47] The geometry of the cluster, Figure 5A, consists of a Cu 8 S 12 core arranged into an icosahedron with 6 faces consisting of 4 copper atoms and 4 sulfur atoms (Figure 5B). The 8 copper atoms form an almost perfect cubic geometry.…”