A series of original heteroleptic dirhodium(II) complexes (4a-j) of formula Rh2(OAc)3(L), where L is a redox-active ferrocenecarboxylate ligand, has been prepared. These dirhodium(II) complexes have been characterised by NMR, mass spectrometry and cyclic voltammetry. All complexes show a quasi-reversible redox behaviour for the ferrocenyl unit. The latter can be selectively oxidised by [N(4-C6H4Br)3]+.BF4-. Four selected heteroleptic complexes 4a, 4b, 4f and 4i, have been evaluated as catalysts for the intramolecular decomposition of a diazo compound. The ratio between the aromatic substitution product 6 and the aliphatic C-H insertion product 7 increases (up to 19% increase) when using the in situ generated oxidised form of the dirhodium(II) complexes (4a+BF4- to 4i+BF4-). This shows that the oxidation of the ferrocenecarboxylate ligand has an effect on the chemoselectivity of the dirhodium-catalysed diazo decomposition, and thus that the electronic properties of a complex can be tuned without exchanging ligands.