The synthesis and crystal structure of the first trimetallic iodo-gold-silver-platinum cluster, [(Ph 3 P) 6 Au 6 Ag 6 Pt(AgI 3 ) 2 ](THF) 2 , with a centered icosahedral metal core and two planar AgI 3 capping units are described. The cluster core serves as the basic building block for a new series of trimetallic (Au Ag Pt) polyicosahedral clusters with iodo ligands. In the crystal, the clusters form a clathrate structural network capable of stabilizing weakly hydrogen-bonded (THF) 2 dimers.