Nonsuperatomic [Au23(SC6H11)16]- Nanocluster Featuring Bipyramidal Au15 Kernel and Trimeric Au3(SR)4 Motif

We report the X-ray structure of a cyclohexanethiolate-capped [Au-23(SR)(16)](-) nanocluster (counterion: tetraoctylammonium, TOA(+)). The structure comprises a cuboctahedron-based bipyramidal Au-15 kernel, which is protected by two staple-like trimeric Au-3(SR)(4) motifs, two monomeric Au(SR)(2) and four plain bridging SR ligands. Electronic structure analysis reveals nonsuperatomic feature of [Au-23(SR)(16)](-) and confirms the Au-15 kernel and surface motifs. The Au-15 kernel and trimeric staple motif are unprecedented and offer new insight in understanding the structure evolution of gold nanoclusters.