Explain geometrical isomerism in complexes with coordination number 4 and 6 with examples.

In case of disubstituted complexes, the substituted groups could either be adjacent or opposite to each other. This leads to geometric isomerism. Thus, we can prepare square planar complexes such as [Pt(NH₃)₄Cl₂]  in two forms, cis and trans. When the Chlorine atoms are adjacent to each other, we get the cis form. While when two chlorine atoms are opposite, we get the trans-form.