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

We report the synthesis and crystal structure of novel co-ligand phosphine/alkynyl protected Au nanoclusters, with composition [Au 11 (PPh 3 ) 8 (C[triple bond, length as m-dash]CPh-CF 3 ) 2 ](SbF 6 ) (1). The gold atoms in the cluster as a capped crown structure subtend C 3v symmetry with one deriving from a central icosahedron and 10 peripheral Au atoms, and all alkynides are exclusively σ coordination bonding. The mean core diameter is about 5.1 Å and the overall van der Waals diameter can be estimated to be 20.5 Å. The optical absorbance of 1 in solution reveals characteristic peaks at 384 and 426 nm and a shoulder between 450 and 550 nm.