Trinuclear, tetranuclear and octanuclear chalcogenido clusters of molybdenum and tungsten supported by trimethylphosphine ligands

Abstract A variety of trinuclear, tetranuclear and octanuclear chalcogenido compounds of molybdenum and tungsten that are supported by PMe 3 ligands has been synthesized and structurally characterized by X-ray diffraction. For example, the tetranuclear sulfido cluster, Mo 4 S 6 (SH) 2 (PMe 3 ) 6 , has been obtained by reaction of Mo(PMe 3 ) 6 with H 2 S, while the trinuclear selenido and tellurido compounds, Mo 3 Se 5 (PMe 3 ) 6 and Mo 3 Te 5 (PMe 3 ) 6 , may be obtained by thermolysis of Mo(PMe 3 ) 4 Se 2 and Mo(PMe 3 ) 4 Te 2 , respectively. In contrast to the formation of a trinuclear compound analogous to Mo 3 E 5 (PMe 3 ) 6 (E = Se, Te), thermolysis of the tungsten complex, W(PMe 3 ) 4 S 2 , produces the octanuclear sulfido cluster, W 8 S 16 (PMe 3 ) 10 . Of these compounds, Mo 4 S 6 (SH) 2 (PMe 3 ) 6 and W 8 S 16 (PMe 3 ) 10 possess M:S stoichiometries of 1:2 and so may be regarded as molecular derivatives of the respective disulfides, MS 2 , which are important components of hydrotreating catalysts.