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1993 (1)
1Author    Jumn-Min Fan, Yu Wang, Chuen-Her UengRequires cookie*
 Title    Electrostatic Properties of 3-(p-Ethoxyphenyl) sydnone  
 Abstract    The bonding type and characteristic chemical reactions of the sydnone ring have been rationalized by examination of the deformation electron density distribution and electrostatic potential from both experiment and theory. The net atomic charges, bond lengths and bond orders of the title compound confirm the semiaromatic bonding type for the sydnone ring. The highly negative net atomic charge of C4 suggests its susceptibility to electrophilic substitution at this position. The well known 1,3-dipolar cycloaddition reaction of the sydnone ring can be understood by the analysis of the 7 t -o r b i t a l wavefunctions, which give rise to similar deformation densities as the experimental ones. The good agreement between the experimental and theoretical (ab initio calculation using 3-21G basis sets) deformation density distribution of the title compound justifies the use of the same basis set to derive the electrostatic potential. The electrostatic potential map reveals all the possible protonation sites of the sydnone ring at Ol, N2 and 06 with the deepest hole at 06 (84.6 kcal/mole). The molecular structure of 3-(p-ethoxyphenyl)syd-none [1] is shown in Figure 1. The phenyl ring plane and the sydnone ring plane are nearly coplanar (di-hedral angle of 2°). A deformation density study of this compound is presented here using both experimental X-ray diffraction data at 110 K and a split valence basis ab-initio calculation. The deformation densities examined are Ag x _ x , Ag m _ a , and Ag mo _ ao , where ÄQx-x is from conventional X-X (high angle [2], Ag m _ a is from a multipole model [3], Ag mo _ ao is from an ab-initio calculation using a 3-21G basis set [4]. The bond lengths, bond orders and net atomic charges of this compound are presented in Table 1 with com-parison between experimental and theoretical results. Bond lengths and bond orders indicate C5-06 to be Fig. 1. Molecular drawing with thermal ellipsoids at 110 K. 
  Reference    Z. Naturforsch. 48a, 105—108 (1993); received December 28 1991 
  Published    1993 
  Keywords    Sydnone, Deformation charge density, Electrostatic potential 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0105.pdf 
 Identifier    ZNA-1993-48a-0105 
 Volume    48