SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF THE HETEROMETALLIC CLUSTERS CPCOFE(2)(MU(3)-SE)(2)(CO)(6) AND CPCOFE(2)(MU(3)-S)(MU(3)-SE)(CO)(6)

The heterometallic clusters CpCoFe(2)(mu(3)-Se)(2)(CO)(6) (1) and CpCoFe(2)(mu(3)-S)(mu(3)-Se)(CO)(6) (2) were prepared in moderate yield from the room-temperature reaction of the mixed-chalcogenide compound (CO)(6)Fe-2(mu-SSe) with freshly prepared CpCo(CO)(2). Both clusters were characterized by elemental analysis, IR, and H-1, C-13, and Se-77 NMR as well as X-ray diffraction analysis. Compound I crystallized in the triclinic space group P ($) over bar 1, with a = 6.638(1) Angstrom, b = 14.675(4) Angstrom, c = 17.844(7) Angstrom, alpha = 111.37(3)degrees, beta = 100.80(2)degrees, gamma = 89.88(2)degrees, V = 1585.9 Angstrom(3), Z = 4, D-c = 2.35 g cm(-3), R = 3.85% and R(w) = 3.12%. Compound 2 crystallized in the monoclinic space group C2/c with a = 34.994(10) Angstrom, b = 6.599(2) Angstrom, c = 14.766(5) Angstrom, beta = 111.95(3)degrees, V = 3162.7 Angstrom(3), Z = 8, D-c = 2.16 g cm(-3), R = 3.51%, and R(w) = 3.26%. Both clusters consist of square pyramidal cores of Fe2CoSe2 and Fe2CoSSe, respectively, and in each case the Co atom occupies the apical site of the square pyramid.