Au(EtP)Cl: a structurally related cluster to Au(EtP)Cl gives insight into the formation process

The reaction of Et 3 PAuCl with NaBH 4 in EtOH leads to the metalloid gold cluster Au 32 (Et 3 P) 12 Cl 8 ( Au 32 ) or Au 54 (Et 3 P) 18 Cl 12 ( Au 54 ) depending on the work-up procedure of the reaction mixture. The molecular structure of Au 54 is determined by X-ray diffraction and can be described as a fusion of two Au 32 clusters showing a similar solubility. The metalloid cluster Au 54 can be either described by a shell model or as a combination of tetrahedral Au 4 X units (X = Cl, Et 3 P); edge and face sharing, whereas tetrahedral Au 4 units are a central motif in gold cluster chemistry. This novel Au 54 gold cluster gives another unique insight into the formation or decomposition process of metalloid clusters, indicating that Au 32 and Au 54 form from a single yet unknown cluster source. Cluster fusion? A slight change in the synthetic procedure of Au 32 (Et 3 P) 12 Cl 8 leads to the metalloid gold cluster Au 54 (Et 3 P) 18 Cl 12 , giving further insight into the formation mechanism, showing new structural motifs within metalloid gold clusters