[yang09]

Question: Determine the Point group of Trans-dichloroethylene

So the symmetries I found were the Identity symmetry(E), the inversion symmetry(i), and the vertical mirror plane inversion( the mirror is on the plane of the paper, cutting each molecule in half). But from here, I'm lost. I know the point group is not going to be a C,D or S group because there are no rotational axis, atleast that I didn't see. It's either a C_i or sigma_v, but I don't know which. Any help is appreciated

[DevaDevil]

how about the 180^o rotation along the C=C bond?

Cl¹         H²
  \         /
   C¹ = C²
  /         \
H¹         Cl²

and rotated

Cl²         H¹
  \         /
   C² = C¹
  /         \
H²         Cl¹

[Jorriss]

I haven't done point groups in a few months but are you sure it's a vertical mirror plane?