Fluorination Of [OS3CO12] in HF/SbF5 affords [Os(CO)(4)(FSbF5)(2)]. According to its crystal structure (orthorhombic, Pna2(1), a = 1590.3(3), b = 1036.6(1), c = 878.2(2) pm, Z = 4), the two SbF6 units occupy cis positions in the octahedral environment around the Os atom. Fluorination of [Ir-4(CO)(12)] in HF/SbF5 produced three different compounds: (1) [Ir-4(CO)(8)(mu-F)(2)(Sb2F11)(2)] (tetragonal, P (4) over bar n2, a = 1285.2(2), c = 952.9(1) pm, Z = 2). Here, two of the six edges of the Ir4 tetrahedron in [Ir4CO12] are replaced by bridging fluorine atoms. (2) [fac-Ir(CO)(3)(FSbF5)(2)-HF]SbF6.HF (orthorhombic, Pnma, a = 1250.6(l), b = 1340.7(2), c = 1092.6(2) ppm, Z = 4). The Ir-4 tetrahedron in Ir-4(CO)(12) is completely broken down, but the facial Ir(CO)(3) configuration is retained. (3) [mer-Ir(CO)(3)F(FSbF5)(2)] (triclinic, P (1) over bar, a = 834.9(1), b = 86 4.9(1), c = 1060.0(1) pm, alpha = 69.173(4)degrees, beta = 77.139(4)degrees, gamma = 88.856(4)degrees, Z = 2).