Molybdenum cluster compounds with

Compounds 4-7 (Table 1) belong to this group. The physicochemical properties of the given binuclear clusters are close to those of the analogous rhenium and molybdenum compounds with the quadruple M-M bonds and are as a rule isostructural with them [1,89,90]. 

A second example of cluster formation involves the antagonism between molybdenum and copper. The presence of high concentrations of molybdenum in pasture soils is known to lead to symptoms of copper deficiency in animals. This has been attributed to the formation of thiomolyb-dates in the rumen of grazing animals, which then interfere with the metabolism of copper through the formation of cluster compounds of molybdenum and copper. It has been shown that thiomolyb-date, MoS42, readily forms such clusters on reaction with phosphines and copper(II) salts under appropriate conditions. Structures are shown in Figure 38.992,993 Reaction between thiomolybdate and copper compounds in aqueous solution have also been reported.994... 

Molybdenum and tungsten in their lower oxidation states have a profound tendency to form M—M bonds, and therefore cluster compounds, as well as the dinuclear species just discussed in Section 18-C-10. One class of these clusters has already been presented in Sections 18-C-7 and 18-C-8, namely, the trinuclear species such as the M3Of+ and M3SJ+ cores and the cuboidal M4S3+ ones. This section will now deal with a number of other clusters of these elements. 

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