The reaction of cis-[Mo-2(O2C-Fc)(2)(NCCH3)(4)][BF4](2) (cis-1) with two electronically different N,N'- diarylformamidinate (DArF) ligands (DArF = N,N'-bis(p-trifluoromethylphenyl)formamidinate (DTfmpF), N,N'-bis(p-anisyl)formamidinate (DAniF)) results in the isolation of the tris- and monosubstituted complexes [Mo-2(DTfmpF)(3)(O2C-Fc)] (2a) and [Mo-2(DAniF)(O2C-Fc)(3)] (2b). These complexes complete the series of [Mo-2(DArF)n(O2C-Fc)(4-n)] (n = 40) type compounds, thus allowing for a comprehensive study. On the basis of the oxidation potential E-1/2([Mo-2](4+)/[Mo-2](5+)) of all Mo-2 complexes, ligand basicity is found to decrease in the order DAniF > DTfmpF > FcCO(2) >> CH3CN. In addition, no direct electronic interaction between the trans-positioned Fc units in complex 2b is detected, which is attributed to the full overlap of all Fc oxidation processes. Furthermore, the low-energy absorption bands of compounds 2a,b are located at different positions in their respective UV-vis spectra.