Crystal structure of the gold nanoparticle [N(C8H17)4][Au25(SCH2CH2Ph)18]

We report the crystal structure of the thiolate gold nanoparticle [TOA(+)][Au-25(SGH(2)CH(2)Ph)(18)(-)], where TOA(+) = N(C8H17)(4)(+). The crystal structure reveals three types of gold atoms: (a) one central gold atom whose coordination number is 12 (12 bonds to gold atoms); (b) 12 gold atoms that form the vertices of an icosahedron around the central atom, whose coordination number is 6 (five bonds to gold atoms and one to a sulfur atom), and (c) 12 gold atoms that are stellated on 12 of the 20 faces of the Au-13 icosahedron. The arrangement of the latter gold atoms may be influenced by aurophilic bonding. Together they form six orthogonal semirings, or staples, of -Au-2(SCH2CH2Ph)(3-) in an octahedral arrangement around the Au-13 core.