Cnh point groups

point group contains a C axis and a Of, plane, perpendicular to C . For n even the point group contains a centre of inversion i. It also contains other elements which may be generated from these. 

The point group Cj , contains only a plane of symmetry, in addition to I. It is therefore the same as Ci and is usually given the symbol Q. 

The point group is the same as 2 - Molecules belonging to other point groups can be visualized as consisting of two identical fragments of C symmetry back to back with one staggered at an angle of 71/n to the other. 

Apart from these two important examples molecules belonging to point groups are rare. 

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