Lithium areneselenolates

This type of deprotonation procedure can also be applied to prepare lithium or magnesium areneselenolates (143, 148) and sterically hindered silyltelluro-late derivatives of the Group 1 (1A) metals Li, Na, and K (149). An alternative procedure based on the reduction of a diselenide (RSeSeR) with [LiHBEt3] in THF can also afford the desired lithium areneselenolate (32). 

The insertion of sulfur into a reactive metal-carbon bond has been known in organic chemistry for some time, but was mainly used to prepare arenethiols (150). However, this method has only recently found its use in the synthesis of pure lithium arenethiolate complexes, which contain potentially intramolecu-larly coordinating heteroatom donor functions (50, 151). It has since then been reported that this method is also applicable for the preparation of lithium areneselenolates and arenetellurolates (152). This route has also been used for the synthesis of bis(arenethiolato)magnesium complexes with intramolecular coordination (153). 

However, situations where more weakly coordinating ligands such as Et20 (144) are present or where less than stoichiometric amounts (3 equiv) of thf are used (146), already lead to the formation of dimeric aggregates of the type [Li(SAr)L]2 (Fig. 18). Similarly, polynuclear lithium areneselenolates [Li(SeAr)] react with bpy to afford dimeric aggregates [Li(SeAr)(bpy)]2 (32). A trimeric structure, for which details were not reported, has very recently been found for the thiolato mono thf complex [Li(thf)(SC6H2-t-Bu3-2,4,6)]3 (154) the structure of the analogous selenolato complex is also trimeric (155). 

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