Why cis-1,2-dichloroethene is more stable than trans

Why cis-1,2-dichloroethene is more stable than trans


4 Answers

Aman Bansal
592 Points
11 years ago

Dear Yash,

Cis is more stable bcoz cis isomer is a polar molecule whereas the trans isomer is non-polar Both molecules contain polar chlorine-carbon bonds, but in the cis isomer they are both on the same side of the molecule. That means that one side of the molecule will have a slight negative charge while the other is slightly positive. The molecule is therefore polar.

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Aman Bansal

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Ankit Kumar Sharma
48 Points
5 years ago
In cis isomer a interaction occurs between sigma orbital oh Hydrogen-carbon bond and sigma* orbital of chlorine-carbon bond, which is only possible for cis orientation. This interaction gives a partial triple bond character and molecule gets stability. This also occurs in case of difluoroethene.Thank You.Ankit Kumar Sharma, West Bengal, Bsc Student.
dolly bhatia
200 Points
5 years ago
The chemical hardness and electrophilicity deduced either from improved virtual orbital (IVO) energies or from correlated treatments correctly predict that cis-1,2-dichloroethene is energetically more stable than the corresponding trans isomer and ground state energies from multireference perturbation theory with IVO orbital’s agree with these predictions. However, when same quantities are computed using hartee-Fock orbital’s, inconsistencies between the two approaches emerge in predicting stability of isomers of 1,2-dicholoroethenes. The IVO energies are appropriate for computation of hardness related parameters, notably chemical hardness and electrophilicity. 
11 Points
5 years ago
Conjugation occurs in cis isomer as lone pair of one chlorine is transferred to other chlorine through pi bond to vacant 3d orbital of chlorine giving it a double bond like character as well as polarity.

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