The hetero-metal clusters [η5-C5H4C(O)CH2CH 2C(O)OCH3]FeCoM(μ3-S)(CO)8 (M = Mo 1, M = W 2) were prepared by thermal reactions of FeCo2(CO)9(μ3-S) with metal exchange reagent [η5-C5H4C(O)CH2CH 2C(O)OCH3]M(CO)3Na (M = Mo or W) in THF. Cluster 1 reacted with 2,4-dinitrophenylhydrazine at room temperature to yield the cluster hydrazone derivative (μ3-S)CoFeMo(CO)8[η5-C5H 4C(NR)Me] [R = NHC6H3-2,4-(NO2)2] 3. All the compounds were characterized by elemental analyses, IR and NMR spectra. Cluster 1 was determined by single crystal X-ray diffraction. Crystal data: C18H11O11SCoFeMo, Mr = 646.05, triclinic, space group P1̄, a = 8.148(2), b = 10.685(3), c = 13.410(4) Å, a = 100.077(5), β = 102.452(5), γ = 91.108(6)°, V = 1120.4(5) Å3, Z = 2, Dc = 1.915 g/cm3, F(000) = 636, μ = 2.071 mm-1, the final R = 0.0378 and wR = 0.0968 for 5074 observations with (I > 2σ(I)). ; Department of Applied Biology and Chemical Technology