'Passivated Precursor' Approach to All-Alkynyl-Protected Gold Nanoclusters and Total Structure Determination of Au.

A 'passivated precursor' approach is developed for the efficient synthesis and isolation of all-alkynyl-protected gold nanoclusters. Direct reduction of dpa-passivated precursor Au-dpa (Hdpa=2,2'-dipyridylamine) in one-pot under ambient conditions gives a series of clusters including Au(C≡CR) (R=-CH-2-F), Au(C≡CR), Au(C≡CR), Au(C≡CR), and Au(C≡CR). These clusters can be well separated via column chromatography. The overall isolation yield of this series of clusters is 40 % (based on gold), which is much improved in comparison with previous approaches. It is notable that the molecular structure of the giant cluster Au(C≡CR) is revealed, which presents important information for understanding the structure of the mysterious Au nanoclusters. Theoretical calculations indicated Au(C≡CR) has a smaller HOMO-LUMO gap than Au(S-CH-4-CH). This facile and reliable synthetic approach will greatly accelerate further studies on all-alkynyl-protected gold nanoclusters.