The reaction between RuCl(C=CHBut)(PPh3)(η-C5Me5) and Fe2(CO)9 afforded the salt [Ru(CO)2(PPh3)-(η-C5Me5)] [Fe3(µ3-C2But)(CO)9], which has been characterized by a single-crystal X-ray structure determination. The cation has a piano-stool structure, while the anion contains a CCBut ligand sitting on a triangular Fe3 cluster.