Synthesis, characterization and properties of Mo6S8(4-tert-butylpyridine)6 and related M6S8L6 cluster complexes (M = Mo, W)

Abstract

Octahedral molybdenum chalcogenide clusters are the building blocks of the well-known Chevrel phases. Although the synthesis of molecular Mo₆S₈L₆ (L = PEt₃ and pyridine) clusters has been previously reported, a high yield and larger scale synthetic procedure is needed to produce soluble Mo₆S₈L₆ (L = Lewis base ligand) clusters, so that they can be used as precursors for the construction of novel network structures. Using the previously developed W₆S₈(4-tert-butylpyridine)₆ synthesis as a starting point, a facile, high yield (70%) synthesis of Mo₆S₈(4-tert-butylpyridine)₆ from (Bu₄N)₂Mo₆Cl₈Cl₆ was developed. This general sulfidation reaction scheme can be extended to the direct preparation of many M₆S₈L₆ (M = W, Mo; L = Lewis base ligand) complexes. Three Mo₆S₈L₆ complexes (L = PEt₃, methylamine, 4,4′-bipyridine) were also prepared via ligand exchange reactions with Mo₆S₈(4-tert-butylpyridine)₆. The above Mo₆S₈L₆ complexes were characterized and their reactivity was compared with their tungsten counterparts. Crystal structures were found for Mo₆S₈(4-tert-butylpyridine)₆, Mo₆S₈(4,4′-bipyridine)₆, and Mo₆S₈(methylamine)₆.