Diphosphine-Stabilized Small Gold Nanoclusters: From Crystal Structure Determination to Ligation-Driven Symmetry Breaking and Anion Exchange Properties.

A new class of small gold nanoclusters with molecular characteristics has been constructed using 1,1'-bis(diphenylphosphino)ferrocene (dppf) as the stabilizing ligand. The identities of the small gold nanoclusters have been fully characterized by NMR, electrospray ionization mass spectrometry, elemental analysis, and single-crystal X-ray diffraction analysis. Octa- and undecagold clusters are found to display different UV-vis absorption behavior. The ligation of the bidentate ligands and halides or pseudohalides has resulted in the symmetry breaking of these nanoclusters with C1 symmetry. The small gold nanoclusters with different coordinating halides or pseudohalides show distinct reactivities and stabilities in ligand/anion exchange experiments. The current research has provided insights into the origin of chirality in the diphosphine-stabilized small gold nanoclusters.