Synthesis and structural characterization of inverse-coordination clusters from a two-electron superatomic copper nanocluster.

We have synthesized and structurally characterized a series of centred cuboctahedral copper clusters, namely Cu{SCNR}{C[triple bond, length as m-dash]CR'}, (where : R = Bu, R' = COMe; : R = Bu, R' = COEt; : R = Pr, R' = COEt; : R = Pr, R' = 3,5-(CF)CH); [Cu(μ-S){SCNR}{C[triple bond, length as m-dash]CR'}], ; Cu(μ-Cl){SCNR}{C[triple bond, length as m-dash]CR'}, (where : R = Bu, R' = Ph); Cu(μ-Br){SCN Bu}{C[triple bond, length as m-dash]CPh}, ; and [Cu(μ-Cl)(μ-Cl){SCN Bu}{C[triple bond, length as m-dash]CCOMe}] . Cluster is the first structurally characterized copper cluster having a Cu centered cuboctahedral arrangement, a miniature of the bulk copper structure. Furthermore, the partial Cu(0) character in the 2-electron superatoms was confirmed by XANES. Inverse coordination clusters are the first examples of copper clusters containing main group elements (Cl, Br, S) with a hyper-coordination number, twelve. A combined theoretical and experimental study was performed, which shows that the central copper (formally Cu) in nanoclusters can be replaced by chalcogen/halogen atoms, resulting in the formation of clusters which show enhanced luminescence properties and increase in the ionic component of the host-guest interaction as Br ≈ Cl > S > Cu, which is consistent with the Cu-X Wiberg indices. The new compounds have been characterized by ESI-MS, H, C NMR, IR, UV-visible, emission spectroscopy, and the structures , , and were established by X-ray diffraction analysis.