Six trinuclear substituted complexes of the type Ru-3(CO)(9)(arphos)(L) were synthesized by a substitution reaction involving Ru-3(CO)(10)(arphos) (1) with L, where L = PCy3, PPh3, P(C6H4F-m)3, P(C6H4F-P)(3), P(C6H4Cl-p)(3) and PPh(C6H4OMe-p)(2), using a thermal method. The structures of the resulting clusters were elucidated by single crystal X-ray diffraction, complemented by means of elemental analysis and spectroscopic methods, including infrared spectroscopy and H-1, C-13{H-1} and P-31{H-1} NMR spectroscopy. The longest Ru-Ru bond in Ru-3(CO)(9)(arphos)(L) [L = PCy3 (2), P(C6H4F-m)(3) (4), P(C6H4F-P)(3) (5), P(C6H4Cl-p)(3) (6) and PPh(C6H4OMe-P)(2) (7)] is the bond that is cis to the monodentate phosphine ligands, while in Ru-3(CO)(9)(arphos)PPh3 (3), the longest bond is the bond that is bridged by the arphos ligand.