New macrocyclic ligands. XI Synthesis, X-ray structure and computational studies of a new N2O4S2-heteroatom cage

Atkinson, Ian M.;Hockless, David C.R.;Lindoy, Leonard F.;Matthews, Owen A.;Meehan, George V.;Skelton, Brian W.;White, Allan H.

Ian Atkinson

Abstract

The synthesis and single-crystal X-ray structure determination of a new cage molecule containing four oxygen, two sulfur, and two nitrogen heteroatoms are described. The structure determination shows that a twist occurs about each (tribenzyl) nitrogen bridgehead so that an overall helical configuration within putative quasi-2 symmetry is generated; both nitrogens have their lone pairs orientatedexo. Single crystals of this compound are homochiral. Semiempirical MO calculations have been used to probe the topological rigidity of this system relative to the more symmetrical analogue incorporating six oxygen and two nitrogen heteroatoms reported previously. The introduction of the sulfur atoms appears to restrict the facile interconversion between enantiomers that was predicted for the N₂O₆-analogue mentioned above. The implications of the structure for the design of larger cages are discussed

Journal

Australian Journal of Chemistry

Publication Name

Australian Journal of Chemistry

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ISBN/ISSN

1445-0038

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CSIRO Publishing

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DOI

10.1071/CH00132