Two novel diaryl(alkoxy)(acyloxy)spiro-λ4-sulfanes (3 and 5) exhibiting isomerism in relation to swapping of the five- and six-membered spiro-rings and two analogous cyclic alkoxysulfonium salts (4 and 6) with intramolecular S ⋯ O interaction have been prepared and their molecular structures determined by X-ray diffraction. In all cases the arrangement of the ligands about the central sulfur atom shows a slightly distorted trigonal bipyramidal (TBP) geometry. In unsymmetrical spiro-λ4-sulfanes the S-O(alkoxy) and the considerably polarized S-O(acyloxy) bond lengths are 1.686(2) and 2.109(2) Å for 3 and 1.683(2) and 2.047(2) Å for 5, respectively. In the analogous cyclic sulfonium salts the corresponding interatomic distances are 1.645(3) and 2.255(3) Å for 4 and 1.616(2) and 2.349(2) Å for 6, respectively. The sums of the individual S-O interatomic distances found in the investigated spiro-λ4-sulfanes and cyclic alkoxysulfonium salts are 3.795(2) and 3.730(2) Å for 3 and 5, whereas they are 3.900(3) and 3.965(2) Å for 4 and 6, showing a significant difference between the two intervals. The individual S-O(alkoxy), S-O(acyloxy), S ⋯ O(carbamoyl) and S-Car bond lengths, as well as the Car-S-Car bond angles are compared and discussed. The five- and six-membered spiro-rings assume a flattened envelope and a somewhat inverted half-chair conformation, respectively. The almost linear O-S-O bond system is not affected significantly by the different size of the spiro-rings except the case of sulfur-oxygen nonbonded interaction.
|Number of pages||9|
|Journal||Journal of the Chemical Society. Perkin Transactions 2|
|Publication status||Published - May 1997|
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