Cation Binding Properties and Molecular Structure of the Crystalline Complex (Aza-12-crown-2)2*NaI

Article abstract of DOI:10.1021/jo00382a028

Aza-12-crown-4 forms a 2:1 sandwich complex similar to that known for 12-crown-4 sodium iodide, except that the presence of >NH in each ring makes Na-donor bonds unequal in strength and leads to hydrogen bonding with the counterion.The heteroatoms of each macroring are coplanar, and both nitrogens are on the same side of the complex (twist angle 43 deg from eclipsed).This may be due to a long (and weak) hydrogen bond to iodide, an interaction confirmed by analysis using Raman spectroscopy.The previously unreported 1:1 and 2:1 cation affinity constants (anhydrous MeOH , 25 deg C) for this macrocycle are logK_S(1:1) = 1.3 +/- 0.1 and logK_S(2:1) = 2.0 +/- 0.1, respectively.