The tetrahedrane cluster, FeCo2(CO)9(μ3-S), reacts with the redox-active ligand, 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd), to give the disubstituted cluster, FeCo2(CO)7(bpcd)(μ3-S), as the sole product. This diphosphine-substituted cluster contains a cobalt-bound, chelating bpcd ligand. Both IR and 31P NMR spectroscopies have been employed in the solution characterization of FeCo2(CO)7(bpcd)(μ3-S), and the solid-state structure has been unequivocally established by X-ray diffraction analysis. FeCo2(CO)7(bpcd)(μ3-S) crystallizes in the monoclinic space group C2/c, a = 34.494(3) Å, b = 11.4194(9) Å, c = 18.634(2) Å, β = 98.103(7)°, V = 7266.7(9) Å3, Z = 8, and dcalc = 1.584 g/cm3. Cyclic voltammetric studies on FeCo2(CO)7(bpcd)(μ3-S) reveal the presence of two quasireversible redox responses assigned to the 0/1− and 1−/2− redox couples. The orbital composition of these redox couples has been examined by carrying out extended Hückel MO calculations on the model complex FeCo2(CO)7(H4-bpcd)(μ3-S), with the results being compared to related cluster compounds.