Which of the following complexes is not expected to exhibit optical isomerism ?
[Co(NH3)3Cl3]
[Co(NH3)3Cl3] i.e., Ma3b3 type exists in two geometrical forms (facial and meridional)
Both of these are achiral. Hence (b) does not show optical isomerism.
Note: M(aa)2b2, M(aa)b2c2 and M(aa)3 types show optical isomerism.
But Ma4b2 or Ma2b4 type shown only geometrical isomers.