Reaction of the early-late heterobimetallic compound [Cp tt 2 Zr(µ 3 -S) 2 {Rh(CO)} 2 (µ-dppm)] (1) with MeI affords the unusual oxidative addition product [Cp tt 2 Zr(µ 3 -S) 2 Rh 2 (µ-CO)(µ-dppm)(I)(COCH 3 )] (4) showing the presence of a bridging carbonyl and a terminal acetyl ligand. The optimized structure of 4 by DFT calculations is further substantiated by the spectroscopic data of the 13 CO-labeled complex 4*.The same reaction carried out on the structurally related gem-dithiolate dinuclear complexes [Rh 2 (µ- has shown an analogous bonding scheme in the "Rh 2 (µ-CO)P 2 " subunit of complexes 4 and 7. Although both complexes can be formally described as composed of a Rh(III)-Rh(III) unit assuming a ketonic character of the bridging carbonyl ligand, the natural charges on the rhodium atoms and the WBI indexes for the Rh-Rh and CO bonds points out to electronically unsaturated metal centers bridged by a carbonyl ligand lacking ketonic character and a significant metal-metal interaction. In addition, DFT calculations on reaction pathway leading to the formation of 4 evidenced the key role of the bulky "Cp tt 2 Zr" fragment in the course of the reaction.3