ISSN:
0020-7608
Schlagwort(e):
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Geometrical and electronic structures of chlorinated polyacetylene, (CHCl)x, a precursor of one-dimensional conjugated polyyne, have been investigated through experimental and theoretical approaches. Uniaxially oriented (CHCl)x films prepared by means of prolonged FeCl3-doping of mechanically stretched polyacetylene films have been subjected to analyses. Polarized infrared absorption spectra showed a dichroism to confirm an orientation of the (CHCl)x films. On the basis of x-ray diffraction analysis, a fiber period of the (CHCl)x has been determined to be 5.2 ± 0.1 Å. Ab initio crystal orbital calculations have been performed on structural models of infinite polymer systems for the (CHCl)x. Energy gradient optimization afforded a relative stability of three different configurational structures of poly-1,2-dichloroethylene which is assumed to be a planar zigzag all-trans conformation with respect to carbon-carbon single bonds, i.e., di-syndiotactic (dst) 〉 erythro-di-isotactic (e-dit) 〉 threo-di-isotactic (t-dit) structures. In addition, the fiber period of the ist structure was calculated to be 5.2 Å, coinciding with the experimental value of the (CHCl)x. In consequence, it has been demonstrated that the prolonged FeCl3-doping of polyacetylene causes a stereospecific chlorination to yield a stereoregular dst structure of the (CHCl)x. The present results imply that a usage of this sort of chlorination through the chemical doping should provide a novel reaction design, especially to control a stereospecificity of chlorination reaction.
Zusätzliches Material:
6 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/qua.560382408
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