1:1 Molecular Complex Between Water and a Macrocyclic Crown Phosphonamide

The 21-membered macrocycle 3-methyl-11,14,17,20-tetraoxa-2,4-diaza-3phosphatricyclo[20.3.1.1^5,9] heptacosa-1(26),5,7,9(27),22,24-hexaene-3-sulfide and water form a 1:1 inclusion compound, C₂₁H₂₉N₂O₄PS.H₂O. The structure reveals host-guest hydrogen bonding with N and O binding sites. One NH-OH₂ and close contacts with three consecutive O atoms of the polyether chain maintain the water molecule inside the macrocyclic cavity. The thiophosphoryl group is directed outward and the -OCH₂CH₂O- units adopt the (ag ± a) conformation. The crystal is composed of centrosymmetrically related dimeric units of the complex.

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