Armed-azacrown ethers N,N′-bis(4-hydroxy-3,5-dimethylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacylooctadecane 1, N-(4-hydroxy-3,5-dimethylbenzyl)-1,4,7,10-tetraoxa-13-azacyclopentadecane 2 and -1,4,7-trioxa-10-azacyclododecane 3, and their alkali-metal complexes were prepared. Single crystal structures have been determined for 1, 1·KI·3H2O, 1·KSCN·H2O, 2·NaSCN, 2·KSCN, 2·RbSCN and 2·CsSCN, 3,
... [Show full abstract] 3·LiSCN·H2O, 3·LiBr·3H2O and 3·RbSCN. The compounds 1·KI·3H2O and 1·KSCN·H2O are normal 1:1 complexes, but 2·NaSCN, 2·KSCN, 2·RbSCN and 2·CsSCN are novel polymer-like (1:1)n complexes in which the phenolic OH group in the side arm of the crown ether co-ordinates to the cation incorporated in the crown moiety of another molecule. In the complexes of 3, when Li+ is used as guest cation, the normal 1:1 complex is obtained, but Rb+ forms a polymer-like (2:2)n complex. Fourier-transform IR spectra showed that the O–H stretching band of the phenolic OH group in the polymer-like complexes shifted to lower frequency by ca. 210–290 cm–1 compared with those of the corresponding host compounds. Also, 13C NMR titration experiments indicated that the stoichiometry of the alkali-metal complexes with 2 and 3 in CD3CN–CD3OD (5:1) solution is 1:1, and thus they do not form polymer-like complexes under these conditions.