1.3- dithioketonates, reaction with hydrogen

Figure 3-20. The reaction of a 1,3-diketone with hydrogen sulfide only gives a monothio derivative, 3.11, rather than a 1,3-dithioketone.

Similar reactions may occur with 1,3-diketones and 1,3-diketonates, and these reactions have been exploited by co-ordination chemists to prepare novel sulfur containing chelating ligands. The metal-directed reactions are synthetically useful since it is not possible to prepare 1,3-dithioketones by direct reactions of free 1,3-diketones with hydrogen... 

Figure 3-21. The metal directed reaction of a monothio compound with hydrogen sulfide to yield a chelated 1,3-dithioketonate.

However, the dithioketones may be readily prepared by reaction of the metal complexes of the monothio derivatives, 3.11, with hydrogen sulfide (Fig. 3-21). In this case, the metal probably plays a dual role, both in polarising the ligand and stabilising the product. Clearly, the use of a soft metal ion such as lead(it) or platinum(u) is to be preferred in a reaction of this type. 

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