Syntheses and properties of arenediazonium and anilinium cation lariat ether complexes: an “ostrich molecule” complex and evidence for intramolecular sidearm - macroring interaction

The preparation of several novel lariat ethers (macrocyclic crown polyethers having sidearms bearing pendant donor groups) is reported, These compounds are ethers derived from known 2-hydroxymethyl-15-crown-5 or -21-crown-7. The sidearms Include 2-aminophenyl, 2,4-diaminophenyl, 2-nitrophenyl, 2-(3'-nitrobiphenyl), and 2-(3'-aminobiphenyl). In several cases, the amino groups were converted into ammonium salts which showed substantial stabilization by intramolecular hydrogen bonding. Likewise, an -NH₂^+.,BF₃^- complex showed evidence of intramolecular hydrogen bonding. Diazotization of the aminobiphenyl residue produced an arenediazonium cation which underwent intramolecular crown complexation, as judged by infrared spectroscopic studies to form what we call an “ostrich molecule” complex. Addition of N,N-dimethylaniline to the intramolecular arenediazonium cation complex afforded an azo compound, but europium shift reagent studies showed clearly that the diazonium cation reacted outside the macroring.