The nine-vertex ferracarborane salt [N(PPh3)(2)][7,7,7-(CO)(3)-closo-7,1-FeCB7H8] (1) reacts with an excess of [IrCl(CO)(PPh3)(2)] in the presence of Tl[PF6] to form, successively, the bimetallic species [7,7,9,9,9-(CO)(5)-7-PPh3-closo-7,9,1-IrFeCB6H7] (3), in which one {BH}(-) vertex has formally been subrogated by an {Ir(CO)(2)(PPh3)} unit, and the trimetallic complex [6,7,9-{Ir(CO)(PPh3)(2)}-7,9-(mu-H)(2)-7,9,9-(CO)(3)-7PPh(3)-closo-7,9,1-IrFeCB6H6](5), which contains an {FeIr2} triangle. The {FeIrCB6} core in 5 resembles that in 3 with, in addition, the (FeIr)-Ir-... connectivity being spanned by an {Ir(CO)(PPh3)(2)} fragment and the consequent Fe-Ir and Ir-Ir bonds bridged by hydrido ligands. In contrast to the above, treatment of the 10-vertex diferracarborane salt [N(PPh3)(2)][6,6,6,10,10,10-(CO)(6)-closo-6,10, 1-Fe2CB7H8] (2) with the same reagents yields two very different, trimetallic complexes, namely [8,10-{Ir(mu-PPh2)(Ph)(CO)(PPh3)}-8-(mu-H)-6,6,6,10,10-(CO)(5)-closo-6,1 0,1-Fe2CB7H7] (6) and [6,7,10-{Fe(CO)(3)}-6-(mu-H)-6,10,10,10-(CO)(4)-6PPh(3)-closo-6,10,1-IrF eCB7H7] (7). In 6, an exo-polyhedral {IrPh(CO)(PPh3)} moiety is attached to a {closo6,10,1-Fe2CB7} framework via a PPh2-bridged Fe-Ir bond and a B-H -> Ir agostic-type linkage, the iridium center formally having inserted into one P-Ph bond of a PPh3 unit. Complex 7 contains an {IrFeCB7} cluster core, with an exo- polyhedral {Fe(CO)(3)} moiety bridging a {BIrFe} triangular face and with an additional Ir-H-Fe bridge. However, this metal atom arrangement reveals that iridium and iron moieties have exchanged exo- and endo-polyhedral sites with respect to the 10-vertex metallacarborane. X-ray diffraction studies upon 3, 5, 6, and 7 confirmed their novel structural features; some preliminary reactivity studies upon these compounds are also reported.