The crystal structure of 2,3,4,4-tetrachloro-1-keto-naphthalenedihydride at −160°C,

H. Veenvliet and Tiny Migchelsen


Crystals of 2,3,4,4-tetrachloro-1-keto-naphthalenedihydride (β-TKN) are orthorhombic, space group Pnma, a = 10.388 (±3), b = 6.955 (±3), c = 14.281 (± 4) Å. There are four molecules in the cell at special positions with symmetry m. The structure has been determined from 3252 reflections measured with an automatic three-circle diffractometer at −160°C. Anisotropic least-squares refinement gave Rw = 0.069. The geometry of the “benzene” ring of the molecule is similar to that of benzene itself, part of the remaining ring of the molecule shows a strong similarity with chloranil. The values observed for the C–Cl bonds are: C(sp3)–Cl = 1.800 (± 1), C(sp2)–Cl = 1.713 (±2) Å. Molecules at neighbouring mirror planes show a strong Cl…O interaction, Cl…O = 2.973 Å. Further electron-spin-resonance experiments are necessary to give an explanation of the photochromic behaviour of the crystals.

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Zeitschrift für Kristallographie – Crystalline Materials offers a place for researchers to present results of their crystallographic studies. The journal includes theoretical as well as experimental research. It publishes Original Papers, Letters and Review Articles in manifold areas of crystallography.