Crown ethers reactions with organometallic compounds

One of the more important recent developments in organometallic aluminum chemistry has been the formation and isolation of low-coordinate compounds, and, in particular, cations. These were first prepared in reactions of various aluminum reagents with crown ethers to form the inclusion compounds known as liquid clathrates. 71,72 Most of the evidence supports the presence of ion pairs as the basis of the solvent inclusion effect. Indeed, the compound [AlMe2-18-crown-6]+[AlMe2Cl2] was isolated from one such system (the cation is shown in Figure 6(a)).73 This was the first time the Me2Al+ unit had been structurally characterized. 

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