Template Reactions

Multidentate carborane-containing Lewis acids and their chemistry: mercuracarborands

“…This was later proven to be the case [13] and is discussed in Section 2.2. The results of the [12]mercuracarborand-4 and later [9]mercuracarborand-3 studies support the hypothesis that the tetrameric cycle is formed via a kinetic template effect. Further proof of an anion template effect will be discussed in Section 3.…”

“…The first mercuracarborand to be synthesized was the tetrameric [12]mercuracarborand-4 [9]. This was accomplished by reacting 1,2-dilithio-1,2-C 2 B 10 H 10 with mercury(II) chloride in ethereal solvent.…”

“…In a subsequent publication [10], it was found that the [12]mercuracarborand-4 cycle with two bound iodide ion guests could be synthesized in a similar manner using mercury(II) iodide. It was also discovered that this cycle could be freed of complexed iodide ions by treatment with silver acetate without decomposition of the mercuracarborand.…”

“…By definition [12], if in the presence of a template a reaction leads to products that do not form without the template, the reaction is mediated by a kinetic template effect. The initial reaction of dilithiocarborane (A) with the mercury center produces the reactive species, 1-Li-2-HgX-1,2-C 2 B 10 H 10 (B).…”

“…This pathway is also mediated by a template anion that is coordinated to two mercury centers bound to a carborane. Intermediate C can react with A, following along the aforementioned pathway or it can react with B to produce the new intermediate F. Again the process continues until [12]mercuracarborand-4 is formed. This was the first example of an anionic guest acting as a template for host construction ever reported.…”