Structural trends in phosphine-substituted [RuCoxRh3–xH(CO)12](x= 0–3) clusters. Crystal structures of [RuCo3H(CO)11(PR3)](PR3= PMe3 or PMe2Ph), [RuCo2RhH(CO)11(PMe2Ph)], [RuCoxRh3–xH(CO)10(PPh3)2](x= 1–2), and [RuRh3H(CO)11(PR3)](PR3= PMe3 or PMe2Ph)

Abstract
The crystal structures of [RuCo3H(CO)11(PMe3)], [RuCo3H(CO)11(PMe2Ph)], [RuCo2RhH(CO)11(PMe2Ph)], [RuCo1.75Rh1.25H(CO)10(PPh3)2], [RuCoRh2H(CO)10(PPh3)2], [RuRh3H(CO)11(PMe3)], and [RuRh3H(CO)11(PMe2Ph)] show [Rh4(CO)12]-like ligand arrangements with phosphines on basal rhodium or cobalt atoms. The phosphines are axially co-ordinated except in the last two compounds, where equatorial co-ordination is found. Hydrides bridge Ru–Rh edges in [RuRh3H(CO)11(PR3)](PR3= PMe3 or PMe2Ph) and basal M3 faces in the other compounds. Geometric parameters are discussed with respect to the metal combination or ligand site.