Fig. 4: X-ray crystal structures of crown ether urea and thiourea axle rotaxanes.
From: Weak functional group interactions revealed through metal-free active template rotaxane synthesis
a Rotaxane 15. Hydrogen bond lengths [Å]: O1—H25C, 2.66; O1-H27C, 2.71; O8—H1N, 2.12; O9—H2N, 2.65. Hydrogen bond angles (deg): O1—H25C, 145.4; O1-H27C, 165.0; O8—H1N, 169.7; O9—H2N, 143.2. b Rotaxane 17. Hydrogen bond lengths [Å]: O2—H1N, 2.41; O3—H1N, 2.32; O3—H2N, 2.74. Hydrogen bond angles (deg): O2—H1N, 126.9; O3—H1N, 158.3; O3—H2N, 148.5. NH···O and CH···O hydrogen bonds shown in dark green. Solvate molecules and other hydrogen atoms omitted for clarity.
