Synthesis and characterisation of four bimetallic gold-gallium clusters with Au-Ga rings as a new structural motif in gold cluster chemistry.

Using the newly introduced reducing agent in gold cluster chemistry GaCp, four new bimetallic gold-gallium cluster compounds were synthesised, stabilised by alkylphosphine ligands. The gold core of Au 6 (GaCl 2 ) 4 (PEt 3 ) 6 , Au 7 (GaCl 2 ) 3 (P n Pr 3 ) 6 and Au 13 (GaCl 2 ) 5 (GaCl)(P n Pr 2 n Bu) 9 is composed of two, three and four Au 4 tetrahedra, linked in different ways. This arrangement gives the last-mentioned cluster the shape of a five-pointed star. A fourth synthesised metalloid gold cluster Au 13 (GaCl 2 ) 5 (P n Pr 3 ) 9 consists of a voluminous gold core encircled by a gold-gallium chain. These gold-gallium chains are present in all four cluster compounds and are similar to the well-known gold-sulphur staple motifs in thiol-stabilised gold cluster compounds.