We relied on the density functional theory (DFT) to study the electronic structure of the [2Fe-2S*](SH)(4) model of the active site of 2Fe ferredoxins and other proteins containing reduced [2Fe-2S*] clusters. The two (Fe3+-Fe2+- S-H) dihedral angles Omega(1) and Omega(2) defined for the two ligands on the ferrous side were allowed to vary, while the two other (Fe2+-Fe3+-S-H) angles Omega(3) and Omega(4) on the ferric side were kept constant. The Lande (g), magnetic hyperfine, and quadrupole tensors for two geometries, C-2 (Omega(1) = Omega(2)) and Cs(Omega(1) = -Omega(2)), were calculated. To apply our model to the actual proteins, we listed all of the crystallographic structures available for the [2Fe-2S*] systems. A classification of these proteins, based on the four dihedral angles {Omega(i)}(i=1-4), separates them into three main classes. The main structural feature of the first class (Omega(1) approximate to Omega(2)), with an average dihedral angle Omega(av) = (Omega(1) + Omega(2))/2 comprised between 115degrees and 150degrees, corresponds to a local ferrous C-2 geometry (rather than C-2v, as previously assumed by Bertrand and Gayda: Biochim. Biophys. Acta 1979, 579, 107). We then established a direct correlation between the three principal g values and Omega(av). It is the first time that such a link has been made between the spectroscopic and structural parameters, a link, moreover, fully rationalized by our DFT calculations. We finally point out the basic differences between our C-2 results with those of the C-2v phenomenological model proposed in the late 1970s by Bertrand and Gayda.