Metal complexes with ligands that coordinate via the nitrogen atom of azo (NN) or imino (CN) groups are of interest due to their π-acceptor properties and redox-active nature, which leads to interesting (opto)­electronic properties and reactivity. Here, we describe the synthesis and characterization of rhenium­(I) tricarbonyl complexes with neutral N,N-bidentate formazans, which possess both NN and CN fragments within the ligand backbone (Ar1-NH-NC­(R3)-NN-Ar5). The compounds were synthesized by reacting equimolar amounts of [ReBr­(CO)5] and the corresponding neutral formazan. X-ray crystallographic and spectroscopic (IR, NMR) characterization confirmed the generation of formazan-type species with the structure fac-[ReBr­(CO)3(κ2-N 2 ,N 4(Ar1-N1H-N2C­(R 3)-N3N4-Ar5))]. The formazan ligand coordinates the metal center in the ‘open’ form, generating a five-membered chelate ring with a pendant NH arm. The electronic absorption and emission properties of these complexes are governed by the presence of low-lying π*-orbitals on the ligand as shown by DFT calculations. The high orbital mixing between the metal and ligand results in photophysical properties that contrast to those observed in fac-[ReBr­(CO)3(L,L)] species with α-diimine ligands.