Three Complexes of a [2.2]Cryptahemispherand

Abstract

The macrocyclic host 36,37,38-trimethoxy-5,10,15-trimethyl-22,25,30,33-tetraoxa-1,19-diazapentacyclo [17.8.8.13,7.18,12.113,17]octatriaconta-3,5,7(38),8,10,12(37),13,15, 17(36)-nonaene contains a somewhat flexible cavity lined with seven O atoms and two N atoms. The structures of three of its complexes are reported here: that with sodium thiocyanate, (I) {[Na(C38H52N2O7)] SCN}, at 296 K, and those with potassium thiocyanate, (II) {[K(C38H52N2O7)]SCN.H2O}, and caesium perchlorate, (III) {[Cs(C38H52N2O7)]ClO4·H2O}, at 156 K. The host adapts well to Cs+, with effective ninefold coordination; it adapts nearly as well to K+, but is not sufficiently flexible to be a good complexer for the much smaller Na+ ion. In structure (II) and in structure (III), a water molecule forms hydrogen bonds between an O atom of the host and an atom of the anion [N of SCN− in (II), O of ClO4− in (III)].