Mixed-ligand tetrairon-sulfur clusters (C5Me5)2(Ph2C2S2)2Fe4S4 (1) and (C5Me5)2(Ph2C2S2)Fe4S5 (2) were synthesized by refluxing a mixture of (C5Me5)2Fe2(CO)4, elemental sulfur, and PhC≡CPh in mesitylene. Similar treatments using PhC≡CMe and PhC≡CEt instead of PhC≡CPh afforded clusters corresponding to 1, namely (C5Me5)2(Ph(Me)C2S2)2Fe4S4 (3) and (C5Me5)2(Ph(Et)C2S2)2Fe4S4 (4). The reactions of Cp2Fe2(CO)4 with elemental sulfur and alkynes (PhC≡CPh and PhC≡CEt) afforded mixed-ligand clusters Cp2(Ph2C2S2)2Fe4S4 (5) and Cp2(Ph(Et)C2S2)2Fe4S4 (6), respectively, as well as the cubane cluster Cp4Fe4S4. The structures of clusters 1 and 2 were determined by X-ray structural analyses. Cluster 1 bears two C5Me5 and two diphenyldithiolene ligands on the four iron atoms, and there are three Fe—Fe bonds, so that Fe4S4 core is highly distorted. The Fe—Fe bonding distances are 2.711(1), 2.717(1), and 2.789(1) Å. The remaining three distances are 3.400(1), 3.255(1), and 3.270(1) Å. Cluster 2 contains an Fe4S4 core which consists of four iron atoms, three μ3-S ligands, and one μ3-S2 ligand. Three iron atoms in the Fe4S5 core have C5Me5 ligands and the fourth iron atom is coordinated by a diphenyldithiolene ligand. The μ3-S2 ligand is located on the opposite side of the fourth iron atom. There are two Fe—Fe bonds, the lengths of which are 2.716(1) and 2.725(1) Å. The other four distances are long, ranging from 3.300(1) to 3.769(1) Å. Crystals of 1-CH2Cl2 (C49H52Cl2Fe4S8) belong to the monoclinic space group P21/a with a = 20.679(3) Å, b = 20.130(3) Å, c = 12.742(2) Å, β = 104.97(2)°, V = 5124(1) Å3, Z = 4, and R(Fo) = 0.069 for 9193 reflections with |Fo| ≥ 3σ(Fo); those of 2·THF (C49H52Cl2Fe4S8) belong to the monoclinic space group P21/c with a = 17.302(3) Å, b= 17.639(2) Å, c = 17.099(3) Å, β = 102.99(3)°, V = 5058(1) Å3, Z = 4 and R(Fo) = 0.058 for 8164 reflections with |Fo| ≥ 3σ(Fo).