Copper-hydride nanoclusters with enhanced stability by N-heterocyclic carbenes

Abstract

Copper-hydrides have been intensively studied for a long time due to their utilization in a variety of technologically important chemical transformations. Nevertheless, poor stability of the species severely hinders its isolation, storage and operation, which is worse for nano-sized ones. We report here an unprecedented strategy to access to ultrastable copper-hydride nanoclusters (NCs), namely, using bidentate N-heterocyclic carbenes as stabilizing ligands in addition to thiolates. In this work, a simple synthetic protocol was developed to synthesize the first large copper-hydride nanoclusters (NCs) stabilized by N-heterocyclic carbenes (NHCs). The NC, with the formula of Cu31(RS)25(NHC)3H6 (NHC = 1,4-bis(1-benzyl-1H-benzimidazol-1-ium-3-yl) butane, RS = 4-fluorothiophenol), was fully characterized by high resolution Fourier transform ion cyclotron resonance mass spectrum, nuclear magnetic resonance, ultra-violet visible spectroscopy, density functional theory (DFT) calculations and single-crystal X-ray crystallography. Structurally, the title cluster exhibits unprecedented Cu4 tetrahedron-based vertex-sharing (TBVS) superstructure (fusion of six Cu4 tetrahedra). Moreover, the ultrahigh thermal stability renders the cluster a model system to highlight the power of NHCs (even other carbenes) in controlling geometrical, electronic and surface structure of polyhydrido copper clusters.

N-Heterocyclic carbene derivatives to modify gold superatom characteristics. Tailorable electronic and optical properties of [Au11(PPh3)7LCl2]+ as a cluster from relativistic DFT

“…55–64 Earlier examples include that of Shionoya involving the NHC counterpart of the classical Schmidbauer [C(AuPPh 3 ) 6 ] 2+ cluster and the formation of a [Au 13 (NHC) 9 Cl 3 ] 2+ cluster showing a high emission quantum yield by Crudden, 65 which preceded the characterization and applications of several species. 66–74…”

1H NMR global diatropicity in copper hydride complexes

“…Since the discovery of Stryker's reagent, [HCu-PPh 3 ] 6 , 1 now widely employed to regioselectively hydrogenate αβ-unsaturated carbonyl compounds, several copper hydrides complexes have been synthesized. 2–28 The broad variety of applications for these complexes include 23,24,29–31 hydrogen storage, 5,32–36 catalysis, 28,32,37–45 energy storage, 38,32 and energy conversion, 32,46 to give but a few examples. Within this family of compounds, several coordination modes have been observed for Cu–H hydrides such as adopting a bridge position, face-capping or interstitial positions to help to stabilize the cluster.…”

Co-ligand triphenylphosphine/alkynyl-stabilized undecagold nanocluster with a capped crown structure

“…[5][6][7][8][9][10][11] Ligand-protected gold nanoclusters having well-dened compositions and structures are of great signicance in terms of the correlation of structures and properties. [12][13][14] During the past decades, great progress has been made in engineering interfaces of metal nanomaterials via single ligand systems, for instance, phosphine, thiol, alkynyl, halide, and N-heterocylic carbene, [15][16][17][18][19][20][21][22] which readily promote the surface reactivity of nanoclusters, thereby helping to achieve high catalysis performance. 23 The pioneering work of ([Au 11 (PPh 3 ) 7 ](SCN) 3 ) can be traced back to Malatesta et al in 1966, but the structure could not be accurately dened at that time.…”