Electron-rich polyisocyano derivatives Fe-2(S2CnH2n)(CO)(6-x)(CNMe)(x) (x similar to 4) undergo oxidatively induced (FeCp2+) reaction with additional CNMe to give [Fe-2(SR)(2)(CNMe)(7)](PF6)(2), a new class of iron thiolates. Crystallographic characterization established that the 34 e(-) dinuclear core resembles the oxidized (H-2-binding) form of the active sites of the Fe-only hydrogenases, key features being the face-sharing bioctahedral geometry, the mu-CX ligand, and an Fe-Fe separation of 2.61 Angstrom. Oxidation of the phenylthiolate Fe-2(Sph)(2)(CO)(2)(CNMe)(4) led to mononuclear [Fe(SPh)(CNMe)(5)](PF6), which is analogous to [Fe-2(SR)(2)(CNMe)(10)](PF6)(2) formed upon treatment of [Fe-2(S2C3H6)(CNMe)(7)](PF6)(2) with excess CNMe.