Extended Hückel molecular orbital calculations on S6 in the planar D6h configuration and in the bent C2v geometry reveal that the former is favored for S62+ and the latter for S64−. It is shown that the additional six electrons would populate one π* and two σ* orbitals in the planar structure. In contrast, when these hexasulfur fragments are incorporated in triple-decker sandwich compounds the pseudo-D6h structure is favored for [(C5H5)Mo(S6)Mo(C5H5)]6+ but the C2v geometry is predicted for [(C5H5)Mo(S6)Mo(C5H5)]2+ which possesses only four more electrons. The required extra two electrons are shown to originate from a metallic δ-type molecular orbital. These EHMO calculations are in complete accord with some very recent experimental results from Gillespie's laboratory. Keywords: Molybdenum–sulfur clusters, EHMO calculations.