The manipulation of trinuclear ruthenium clusters [Ru3(CO)9(μ-H)2(μ3-PMes)] (1) with PH2Ph, in refluxing hexane, produces [Ru3(CO)8(PH2Ph)(μ-H)2(μ3-PMes)] (2) where PH2Ph coordinates as a terminal ligand. Cluster 2 gets converted to [Ru3 (CO)9(μ3-PMes)(μ3-PPh)] (3) when heated in a toluene solution in the presence of CO. This study provides the solutions of the X-ray structures for clusters 2 and 3.