Acta Cryst. (2002). E58, m68-m69  [ doi:10.1107/S1600536802001654 ]

Rerefinement of (-1,7,11,17-tetraoxa-2,6,12,16-tetraazacycloeicosane-⁴N¹,N¹⁷:N⁷,N¹¹)bis[dichlorozinc(II)]

V. A. Kuksa, S. M. S. V. Wardell, P. K. T. Lin and R. A. Howie

Abstract: This rerefinement of the title compound, [Zn₂Cl₄(C₁₂H₂₈N₄O₄)], based on the original intensity data, differs from the original only in the exchange of the NH and O moieties of the oxaaza-macrocycle, resulting in a dramatic improvement in the R factors and the anisotropic displacement parameters associated with the N and O atoms. The tetrahedral coordination of Zn involves Cl at 2.2144  (6) and 2.2279  (6)  Å, but now N rather than O at 2.0563  (18) and 2.0934  (17)  Å, in keeping with the usual arrangement for zinc complexes of this type. The revised model permits satisfactory N-HCl hydrogen bonds which the original did not. A crystallographic twofold axis passes through the centroid of the molecule perpendicular to its least-squares plane.

Online 31 January 2002

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