Molekül- und Kristallstruktur von 9λ4-Thia-2,4,6,8,10,11-hexaza-1λ5,3λ5,5λ5,7λ5-tetraphosphabicylo[5.3.1]undeca-1,3,5,7(11),8,9-hexaen,einem schwefeldiimidoüberbrückten Cyclotetraphosphazen |
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Authors: | A Gieren B Dederer |
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Abstract: | Molecular and Crystal Structure of 9λ4-Thia-2,4,6,8,10,11-hexaaza-1λ5,3λ5,5λ5,7λ5-tetraphosphabicylo5.3.1]undeca-1,3,5,7(11),8,9-hexaene, Cyclotetraphosphazene Bridged by a Sulfur Diimide Group We have carried out an X-ray structure analysis of the title compound ( 1 ). 1 crystallizes in the monoclinic space group P21/b with a = 9.436(4), b = 20.102(7), c = 11.622(5) Å, γ = 103.52(8)°, Z = 8. There are two molecules in the asymmetric unit, which in approximation can be transformed one into the other by additional symmetry elements of a substructure of a space group B2/b. The S = N bond lengths are 1.53 Å. The P? N bonds connecting the SN2 system are 1.666 Å long. They are significantly longer than the P? N multible bonds in the P4N4 ring within a range of 1.517 to 1.565 Å. The sulfur diimide unit and its substituents are coplanar causing a half-boat conformation of the heterocyclic six membered ring. The cyclotetraphosphazene ring shows a flattened crown-saddle conformation, the phosphorous atoms arranged nearly at the corners of a square. Influenced by crystal packing there exist small deviations from the molecular mirror plane and also differences in conformation between the two molecules of the asymmetric unit. |
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