The reactions of Fe(CO)(5) with poolysulfides and polyselenides of various chain lengths and stoichiometries were investigated. It was found that Fe(CO)(5) must always be present in excess relative to the polychalcogenide chain, or immediate decomposition would result. Conversely, if Fe(CO)(5) is present in large excess [Fe-3(CO)(9)(mu(3)-E)](2-)(E = S, Se) is formed in excellent yield. This was isolated in very good yield as its [Ph(4)P](+) salt. The salt [Ph(4)P](2)[Fe-3(CO)(9)(mu(3)-Se], Ib, crystallizes in the triclinic space group P (1) over bar; a = 11.580(4) Angstrom, b = 12.369(3) Angstrom, c = 19.707(4) Angstrom, alpha = 88.18(2)degrees, beta = 81.78(2)degrees, gamma = 71.32(2)degrees, V = 2646(1) Angstrom(3), Z = 2, R = 0.0322, R(w) = 0.0358. As the ratio and chain length of polychalcogenide are increased, there is increased oxidation of the iron centers, leading to clusters with formulas [Fe-5(CO)(14)(mu(3)-E)(2)](2-) and [Fe-6(CO)(12)E(6)](2-) (E = S, Se) successively. The salt [n-Bu(4)N](2)[Fe-5(CO)(14)(mu(3)-S)(2)], II, crystallizes in the monoclinic space group P2(1)/c; a = 33.284(7) Angstrom, b = 18.769-(4) Angstrom, c = 18.704(4) Angstrom, beta = 90.945(5)degrees, V = 11683(10) Angstrom(3), Z = 8, R = 0.0987, R(w) = 0.1179. The salt [Ph(4)P](2-)[Fe-5(CO)(14)(mu(3)-Se)(2)], III, crystallizes in the triclinic space group P (1) over bar; a = 12.951(4) Angstrom, b = 13.155(6) Angstrom, c = 20.729(8) Angstrom, alpha = 98.01(3)degrees, beta = 94.25(3)degrees, gamma = 115.77(3)degrees, V = 3113(2) Angstrom(3), Z = 2, R = 0.0742, R(w) = 0.0883. The salt [Et(4)N](2)[Fe-6(CO)(12)Se-6], IVb, crystallizes in the monoclinic space group P2(1)/c; a = 12.134(2) Angstrom, b = 12.753(2) Angstrom, c = 16.058(2) Angstrom, beta = 112.51(2)degrees, V = 2348.8(5) Angstrom(3), Z = 2, R = 0.0307, R(w) = 0.0335. The cluster [Fe-6(CO)(12)E(6)](2-) could be used as a [Fe-2(CO)(6)E](2-) transfer group for M(II) salts, leading to formation of [MFe(4)(CO)(12)S-4](2-) (M = Ni, Pd). The salt [Ph(4)P](2)[{Fe-2(CO)(6)(mu(3)-S)(2)}Ni-2]. CH2Cl2, Va, crystallizes in the triclinic space group P (1) over bar; a = 11.270(4) Angstrom, b = 12.038(5) Angstrom, 12.664(5) Angstrom, alpha = 79,53(3)degrees, beta = 82.55(3)degrees, gamma = 89.32(3)degrees, V = 1675(1) Angstrom(3), Z = 1, R = 0.0543, R(w) = 0.0699. Cyclic voltammograms were obtained for all these clusters, identifying other stable oxidation states.