141871-07-0Relevant academic research and scientific papers
Spiro-λ4-sulfanes with intramolecular sulfur-oxygen interactions: Syntheses and molecular structures
Szabo,Kuti,Kapovits,Rabai,Kucsman, A.,Argay,Czugler,Kalman,Parkanyi
, p. 1 - 16 (2007/10/03)
Three novel N-acetylated spiro-λ4-sulfanes with five-membered spirorings (fused with aromatic rings) and with two N heteroatoms (in (1)) or with N and O heteroatoms (in (2) and (3)) in axial positions have been prepared and their molecular structures determined by X-ray diffraction. The molecular structures of compounds (1-3) show trigonal bipyramidal geometry about the central sulfur atom. The rather long axial S-N bonds(1.93 A)in he symmetric spiro-λ4-sulfane (1) exhibit the usual hypervalent character, whereas the S-N (1.73 and 1.80 A) and S-O (2.23 and 2.07 A) bond lengths in the unsymmetric spiro λ4-sulfanes (2) and (3) correspond to elongated covalent S-N bonds and highly polarized S-O hypervalent bonds, respectively. Each structure exhibits usual S-C(ar) bond lengths (1.79-1.81 A). The axial N-S-N/O and the equatorial C(ar)-S-C(ar) angles lie in the intervals 173-179°and 98-103°, respectively. The conformations of (1-3) including the single-cis-single-trans isomerism of the endocyclic and exocyclic amide parts, the shape of the spirorings, and the relative positions of the equatorial aromatic rings are discussed in detail. In (1-3) the exocyclic carbonyl-oxygen approaches the central sulfur atom by 2.90,2.73 and 2.71 A, respectively, leading to an effective intramolecular sulfur-oxygen interaction of 1,4-type. The S···O close contacts, however, do not alter appreciably the trigonal bipyramidal geometry about the central sulfur atom.
