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(GaCl)(PEt), Au(GaCl)(P Pr) and Au(GaCl)(GaCl)(P Pr Bu) is composed of two, three and four Au 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(GaCl)(P Pr) 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.