Point Group Ci: Cl2Br2 Ethane

Build meso-CHClBr-CHClBr with the Indigo® 68821W point group molecular model kit to demonstrate C_i point group symmetry, inversion centers, and meso compound geometry. Ideal for symmetry, group theory, and inorganic chemistry courses.

The Indigo® 68821W model kit builds meso-CHClBr-CHClBr, a clear example of the C_i point group. The model identifies both symmetry elements: the identity operation E and the center of inversion i. With no rotation axis and no mirror plane, the inversion center is the sole symmetry element that maps the molecule onto itself, making C_i one of the simplest point groups. Other C_i molecules include (E)-hex-3-ene, 1,2-dichloro-1,2-difluoroethane, 2,3-dichlorobutane, and (E)-azodioxymethane.

Why Study Point Group Ci Symmetry Operations?

The C_i point group contains exactly two symmetry operations, E and i. These are defined entirely by the presence of an inversion center and nothing else. Meso-CHClBr-CHClBr has two chiral centers making the molecule achiral because inversion through the center maps one half of the molecule exactly onto the other. This makes C_i a good example of point group theory and stereochemical intersecting. The inversion center is not just a symmetry operation but the geometric feature that accounts for the molecule's physical properties.

In spectroscopy and group theory courses, the C_i point group carries direct spectroscopic consequences. Like all centrosymmetric point groups, C_i obeys the mutual exclusion rule. It has IR active vibrational modes that are Raman inactive and vice versa. The character table for C_i contains two irreducible representations, A_g and A_u, corresponding to Raman active and IR active modes respectively. The C_i meso compound model pairs naturally with the C₁ CFClBrH model to illustrate how the addition of a single inversion center, with no accompanying rotation axis or mirror plane, is sufficient to impose spectroscopic selection rules and remove chirality simultaneously.