The crystal and molecular structures of the hexarhodium carbonyl clusters Rh₆(CO)₁₅L (L = P(OPh)₃, ; P(4-XC₆H₄)₃, (X = CF₃, ; Cl, ; F, ; OMe, ); P(ⁿBu)₃, ; Me₂SO, ; MeCN, ; C₈H₁₄, ) have been determined by single crystal X-ray crystallography. Redetermination of the structure of the parent Rh₆(CO)₁₆ cluster,, has also been performed and all the results are compared with those for the rather disparate group of monosubstituted derivatives reported earlier. The structures all relate closely to that of the parent which has an octahedral array of Rh atoms with four opposite faces triply bridged by CO ligands. Each Rh atom also has two terminal CO groups attached. The substituents simply replace one of the terminal COs. A group of ligands, comprised of the P-donors and cyclooctene, all show distortions with a high degree of stereoselectivity in the vicinity