Within the last decade, the ternary molybdenum chalcogenides have played a major role in superconductivity: opening of the ternary superconductor range, competition between superconductivity and magnetism. It is mainly due to the pseudomolecular nature of the Mo6X8 unit. In these materials, the Mo6 cluster plays the electron-acceptor role and the number of valence electrons per molybdenum atom is related to the Mo-Mo intracluster bonding. The increase of this valence electron concentration (VEC) per molybdenum in new ternary chalcogenides corresponds to larger and larger clusters. These new extended clusters belong to a very large family containing the general Mo3nX3n+2 (n≥2) block unit. The tridimensional stacking of these building blocks provides more and more large channels and leads to a more and more anisotropic character of their physical properties.