Three 18-membered macrocyclic diamides with differing donor atoms and backbone substituents

The crystal structures are reported for 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-6,17-dione, (C₁₂H₂₂N₂O₆), (I), dibenzo[e,q][1,4,10,13,7,16] tetraoxadiazacyclooctadecine-6,13-dione, (C₂₀H₂₂N₂O₆), (II) and 1,4-dioxa-10,13-dithia-7,16-diazacyclooctadecane-8,15-dione, (C₁₂H₂₂N₂O₄S₂), (III). Solid-state structures show different types of hydrogen bonding for all three structures. In I, there are two intermolecular hydrogen bonds between an amide and carbonyl [N–H···O = 2.8206(11) Å and 2.8637(11) Å] and two intermolecular hydrogen bonds between an amide and ether [N–H···O = 2.9570(11) Å and 3.0067(11) Å]. There are two intramolecular hydrogen bonds between amide and ether oxygens [N–H···O = 2.589(3) Å and 2.623(4) Å] in II. Molecule III has a mixture of intramolecular hydrogen bonds between an amide and thioether [N–H···S = 3.0501(18) Å] and intermolecular hydrogen bonds between an amide and carbonyl [N–H···O = 2.835(2) Å].