what are the point groups for

mer- Co Cl3 (CO3)
and
fac- Co Cl3 (CO3)

To determine the point groups for the coordination compounds, we need to consider the symmetry elements present in the molecule. These symmetry elements include rotation axes, mirror planes, and inversion centers.

1. mer-CoCl3(CO)3:
In this compound, "mer" refers to the meridional arrangement of the ligands around the central metal ion. Let's consider the symmetry elements:

a. Rotation axis: There is a C3 rotation axis passing through the central cobalt ion. This axis allows for a rotation of 120 degrees, bringing each ligand to the position of the next ligand.
b. Mirror plane: There is a horizontal mirror plane (σh) passing through the central cobalt ion, bisecting the three ligands, and reflecting the ligands onto their mirror images.

The point group for mer-CoCl3(CO)3 is C3h.

2. fac-CoCl3(CO)3:
In this compound, "fac" refers to the facial arrangement of the ligands around the central metal ion. Let's examine the symmetry elements:

a. Rotation axis: There is a C3 rotation axis passing through the central cobalt ion. However, in this arrangement, a C3 rotation brings ligands from adjacent positions, resulting in no change in the molecule's appearance.
b. Mirror plane: There is no mirror plane in this arrangement.

The point group for fac-CoCl3(CO)3 is C3v.

Overall, the point group for mer-CoCl3(CO)3 is C3h, while the point group for fac-CoCl3(CO)3 is C3v.