A series of six novel cluster complexes [M₆I₈(SAr^f)₆]²⁻ (M=Mo or W; SAr^f=p-SC₆F₄-C₆F₅, p-SC₆F₄Cl, or p-SC₆F₄CF₃) was prepared by exchange reactions between [Mo₆I₁₄]²⁻ or [W₆I₁₄]²⁻ and silver salts of the corresponding thiols and characterized by X-ray single-crystal diffraction and elemental analysis, NMR, ESI-MS, and CV techniques. In the crystal structures all the thiolate ligands adopt an idiosyncratic orientation along one of the idealized three-fold axes passing through two opposite μ₃-I ligands and the centers of two opposite faces of the M₆ octahedra. This leads to shortened intramolecular C⋅⋅⋅I distances inside the cluster below 3.5 Å. The clusters exhibit red photoluminescence with relatively high quantum yield, up to 0.42 in the case of (Bu₄N)₂[W₆I₈(SC₆F₄CF₃)₆]. Moreover, all the compounds exhibit X-ray luminescence; the close values of the maxima in the photo- and X-ray induced emission spectra indicate that the luminescence is cluster-centered.