Chalcogen tungsten

The first examples of a chalcogen insertion into a transition metal-carbene bond were reported in 1981. Stirring solutions of the pentacarbonyl-(diarylcarbene)tungsten complexes 39 in pentane in the presence of solid sulfur afforded the thioketone complexes 40 [Eq. (8)].171 The reaction rate increased considerably when pentane was replaced by CS2 as the solvent due to the higher solubility of elemental sulfur in CS2. 

In 222, the Mo atom occupies the common apical site of two distorted square-pyramidal cores, in each of which the two Fe atoms, one Se atom, and one Te atom occupy the basal sites. The formation of 222 demonstrates the contrast in the influence of the chalcogens in cluster-expansion reactions. Although 77 readily reacts with [M(CO)s(THF)] (M = W, Mo) to form [Fe2M(CO)io(/i3-Se)2] (M = W (217), Mo (218)), 110 reacts with the tungsten compound only to form 216 formation of [Fe2Mo(CO)io((u.3-Te)2] is not observed. An intermediate situation arises when the mixed-chalcogenide compound 114 is used for reacting with [Mo(CO)5(THF)]. The formation... 

Tungsten coordination has recently been comprehensively reviewed in Comprehensive Coordination Chemistry, particularly in the areas of mononuclear complexes, dinu-clear species containing single and multiple W-W bonds, polyoxometaUate synthesis, structure, and reactivity, and chalcogen-containing cluster complexes. ... 

B7.26 Chalcogen clusters of chromium, molybdenum, tungsten and rhenium... 

A few metal complexes of selenothioic and diselenoic acids have been reported. In a study on the reactivity of metal-carbon triple bond compounds toward chalcogens, it was found that molybdenum (52) and tungsten (53) carbyne complexes reacted with elemental selenium to yield the corresponding di-selenoate complexes 54 and 55, respectively (Eqs. 13 and 14) [18]. 

Chalcogen incorporation was monitored in the syntheses in Scheme 5.10 compound labels 40-44 in this scheme refer to general cluster core configurations without specific reference to terminal ligands. All reactions involved heterometallic clusters prepared from the facially chelated mononuclear molybdenum or tungsten trisulfide species 38 and 39, and from the previously described MoFe3S4 cubane 12-Mo site-specific... 

MOLYBDENUM AND TUNGSTEN CLUSTERS AS AQUA IONS [M3Q4(H20)9] + (M = Mo,W Q = S,Se) AND RELATED CHALCOGEN-RICH TRINUCLEAR CLUSTERS... 

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