A reinvestigation of the crystal and molecular structure of (18-crown-6) · 2 CH3NO2:D 3d stabilization via methyl hydrogen-crown oxygen ‘hydrogen bonds’

The title compound was crystallized from hot nitromethane. (18-crown-6) · 2CH₃NO₂ crystallizes in the monoclinic space groupP2₁/n witha=9.066(3),b=8.284(3),c=14.015(7) Å, =101.83(5)^o andD _calc=1.25 g cm^–3 forZ=2. Least-squares refinement using 890 independent observed reflections led to a final conventionalR value of 0.084. The hydrogen atoms were located but not refined. The crown ether resides about a crystallographic center of invertion. There are two nitromethane molecules (one centered above and one below the crown ether) weakly interacting with the crown oxygen atoms via the methyl hydrogens stabilizing aD _3d crown conformation. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82029 (5 pages).