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.