H₃Ru₃(CO)₉(μ3-COMe) can be readily deprotonated to generate the cluster anion [H₂Ru₃(CO)₉(μ-COMe)]^-. This anion reacts with MPPh_3Cl (M = Cu, Ag or Au) or [Rh(CO)_3(PPh_3)_2]^+ to give the tetranuclear species H_2Ru_3(CO)_9(μ3-COMe)(MPPh_3) or H_2Ru_3(CO)_9(μ3COMe)(Rh(CO)_2PPh)_3 respectively which consist of a tri-ruthenium unit face-bridged by COMe and edge-bridged by the heterometal. The clusters H_2Ru_3(CO)_9(μ3-COMe)(MPPh_3) react rapidly with PPh_3 to form the monosubstituted derivatives H_2Ru_3(CO)_8PPh_3(μ3-COMe)(MPPh_3) which have analogous structures. H_2Ru_3(CO)_9(μ3-COMe)(Rh(CO)_2PPh_3) rearranges with loss of CO to give H_2Ru_3Rh(CO)_10PPh_3(μ-COMe) which consists of a tetrahedral metal core with a Ru-Ru bond edge-bridged by COMe. In solution, this cluster exits as 2 isomers, the structure of the most abundant of these corresponding to that in the solid state. Treatment of H₂Ru₃Rh(CO)₁₀PPh(μ-COMe) with K[HBBu^s_3] forms an anionic mixture of [H_2Ru_3Rh(CO)_11PPh_3]^- and [HRu_3Rh(CO)_10PPh_3(COMe)]^-. [H_2Ru_3Rh(CO)_11PPh_3]^- has a tetrahedral metal core with an arrangement of ligands analogous to that of Rh_4(CO)_12. Reaction of the anionic mixture with [Rh(CO)_3(PPh_3)_2]^+ generates H_2Ru_3Rh_2(CO)_12(PPh_3)_2 which has a trigonal bipyramidal (tbp) metal core with the 2 Rh atoms occupying the apical sites. Reaction of the anionic mixture with AuPPh_3Cl leads to isolation of HRu_3RhAu(CO)_10(PPh_3)_2(μ3-COMe) and H_2Ru_3RhAu(CO)_11(PPh_3)_2 with the former also consisting of a tbp metal core. The reaction of [H_2Ru_3(CO)_9 (μ3-COMe)]^- with [Rh(CO)_3(PPh_3)_2]^+ also leads to formation of HRu_3(CO)_9PPh_3 (μ-COMe), HRu₃(CO)₈(PPh₃)₂ (μ-COMe) and H_2Ru_3Rh(CO)_8(PPh_3)_3 (μ-COMe). HRu₃(CO)₉PPh₃ (μ-COMe) has a structure analogous to that of HRu_3(CO)_10 (μ-COMe) but with an equatorial CO ligand bound to one of the bridged Ru atoms replaced by PPh₃. Cooling a solution of this species leads to the formation of 2 isomers due to loss of rotation of the COMe ligand about the C-OMe bond, each isomer arising from a different orientation of the Me group. The anion [H₂Ru₃(CO)₉(μ3-COMe)]^- also reacts with Rh(CO)(PPh₃)₂Cl which generates the heterometallic cluster H₂Ru₃Rh(CO)₉(PPh₃)₂(μ-COMe). In solution, this cluster exists as 4 isomers at room temperature and 5 isomers at 213K with a general structure believed to be similar to that shown by H_2Ru_3Rh(CO)_10PPh_3(μ-COMe).