Crystal structures of an azobenzene-bridged aza-18-crown-6 cryptand and a sodium complex thereof

We report the single-crystal X-ray diffraction structures of the azo-benzene-bridged aza-18-crown-6 cryptand 7,16-[3,3'-(diazene-1,2-di-yl)bis-(1,3-phenyl-enecarbon-yl)]-1,4,10,13-tetra-oxa-7,16-di-aza-cyclo-octa-decane, C₂₆H₃₂N₄O₆, <b>1</b>, and its sodium complex poly[[{μ-7,16-[3,3'-(diazene-1,2-di-yl)bis-(1,3-phenyl-enecarbon-yl)]-1,4,10,13-tetra-oxa-7,16-di-aza-cyclo-octa-deca-ne}bis-{tetra-kis-[3,5-bis-(tri-fluoro-meth-yl)phen-yl]borato}disodium] benzene disolvate], {[Na₂(C₃₂H₁₂F₂₄B)₂(C₂₆H₃₂N₄O₆)]·2C₆H₆} _<i>n</i> . The free ligand <b>1</b> crystallizes in space group <i>P</i>2₁/<i>n</i> and adopts an elongated strain-distorted crown conformation with a slightly twisted azo-benzene unit. In contrast, <b>2</b> [obtained with sodium tetra-kis-3,5-bis-(tri-fluoro-meth-yl)phenyl borate (NaBArF)] crystallizes in space group <i>P</i>1 and features multiple Na⁺ centers that assemble into a three-dimensional network in the solid state. Hirshfeld surface analysis was used to provide a complementary, qu-anti-tative description of the dominant inter-molecular contacts governing the crystal packing.