Controlling Gold Nanoclusters by Diphospine Ligands

We report the synthesis and structure
determination of a new Au22 nanocluster coordinated by
six bidentate diphosphine ligands:
1,8-bis­(diphenyl­phosphino) octane (L8 for short).
Single crystal X-ray crystallography and electrospray ionization mass
spectrometry show that the cluster assembly is neutral and can be
formulated as Au22(L8)6. The Au22 core consists of two Au11 units clipped together
by four L8 ligands, while the additional two ligands coordinate
to each Au11 unit in a bidentate fashion. Eight gold atoms
at the interface of the two Au11 units are not coordinated
by any ligands. Four short gold–gold distances (2.64–2.65
Å) are observed at the interface of the two Au11 clusters
as a result of the clamping force of the four clipping ligands and
strong electronic interactions. The eight uncoordinated surface gold
atoms in the Au22(L8)6 nanocluster
are unprecedented in atom-precise gold nanoparticles and can be considered
as potential in situ active sites for catalysis.