Synthesis, characterization and properties of Mo_6S_8(4-tert-butyl-pyridine)_6 and related M_6S_8L_6 cluster complexes (M = Mo, W)

摘要

Octahedral molybdenum chalcogenide clusters are the building blocks of the well-known Chevrel phases. Although the synthesis of molecular Mo_6S_8L_6 (L = PEt_3 and pyridine) clusters has been previously reported, a high yield and larger scale synthetic procedure is needed to produce soluble Mo_6S_8L_6 (L = Lewis base ligand) clusters, so that they can be used as precursors for the construction of novel network structures. Using the previously developed W_6S_8(4-tert-butylpyridine)_6 synthesis as a starting point, a facile, high yield (70%) synthesis of Mo_6S_8 (4-tert-butylpyridine)_6 from (Bu_4N_2)Mo_6Cl_8Cl_6 was developed. This general sulfidation reaction scheme can be extended to the direct preparation of many M_6S_8L_6 (M = W, Mo; L = Lewis base ligand) complexes. Three Mo_6S_8L_6 complexes (L = PEt_3, methylamine, 4,4'-bipyridine) were also prepared via ligand exchange reactions with Mo_6S_8(4-tert-butylpyridine)_6. The above Mo_6S_8L_6 complexes were characterized and their reactivity was compared with their tungsten counterparts. Crystal structures were found for Mo_6S_8(4-butylpyridine)_6, Mo_6S_8(4,4'-bipyridine)_6, and Mo_6S_8(methylamine)_6.