Symmetry in complexes

This kind of isomerism occurs when a compound can be represented by two asymmetrical structures, one of which is the mirror image of the other. It is common in octahedral complexes involving bidentate groups for, unless bidentate groups are present, there is always a plane of symmetry in complexes of this shape. The cation of [CoCl2(en)2]Cl has two optically active cis-forms (Fig. 289(a) and (b)) in addition to an inactive trans-form (Fig. 289(c)). [Co(cn)3]Br3 has also been resolved Fig. 290(a) and (b) show the two enantiomorphs of the terpositive cation. 

---