Owing to the inherent instability caused by the low Cu(I)/Cu(0) half-cell reduction potential, Cu(0)-containing copper nanoclusters are quite uncommon in comparison to their Ag and Au congeners. Here, a novel eight-electron superatomic copper nanocluster [Cu 31 (4-MeO-PhC�C) 21 (dppe) 3 ](ClO 4 ) 2 (Cu 31 , dppe = 1,2-bis(diphenylphosphino)ethane) is presented with total structural characterization. The structural determination reveals that Cu 31 features an inherent chiral metal core arising from the helical arrangement of two sets of three Cu 2 units encircling the icosahedral Cu 13 core, which is further shielded by 4-MeO-PhC�C − and dppe ligands. Cu 31 is the first copper nanocluster carrying eight free electrons, which is further corroborated by electrospray ionization mass spectrometry, X-ray photoelectron spectroscopy and density functional theory calculations. Interestingly, Cu 31 demonstrates the first near-infrared (750−950 nm, NIR-I) window absorption and the second near-infrared (1000−1700 nm, NIR-II) window emission, which is exceptional in the copper nanocluster family and endows it with great potential in biological applications. Of note, the 4-methoxy groups providing close contacts with neighboring clusters are crucial for the cluster formation and crystallization, while 2-methoxyphenylacetylene leads only to copper hydride clusters, Cu 6 H or Cu 32 H 14 . This research not only showcases a new member of copper superatoms but also exemplifies that copper nanoclusters, which are nonluminous in the visible range may emit luminescence in the deep NIR region.

A pair of alkynyl–diphosphine-coprotected copper­(I) clusters, namely, [Cu6(4-MeO-PhCC)5(dppe)3]­(ClO4) [Cu 6 ; dppe = 1,2-bis­(diphenylphosphino)­ethane] and [Cu11(H)­(4-MeO-PhCC)8(dpppe)3]­(ClO4)2 [Cu 11 ; dpppe = 1,5-bis­(diphenylphosphino)­pentane], featuring trigonal-prismatic frameworks have been synthesized by a reduction method. Their molecular structures are determined by X-ray crystallography and characterized by multiple techniques. The length of the spacer of the diphosphine ligand can directly affect the aspect ratio of the clusters. Cu 6 with dppe as ligands has a trigonal-prismatic core. The longer alkyl spacer of dpppe helps to elongate the trigonal-prismatic framework to form Cu 11 , with its trigonal-prismatic framework encapsulating a Cu5H unit. Electrospray ionization mass spectrometry, 2H NMR, and liberations of hydrogen further verify the presence of a hydride in the cluster. Density functional theory calculations help to locate the position of the hydride and understand the electronic structures of the clusters. Cu 11 is the first alkynyl–phosphine-coprotected copper hydride cluster. These two clusters show distinct luminescence properties. The compact Cu 6 is phosphorescent upon radiation, while the longer Cu 11 with more flexibility is nonluminous. This work enriches the family of copper hydrides and demonstrates the ligand effects in the extension of the length and structural complexity of clusters.

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