[maccha]

Can a square planar molecule with 2 sets of identical atoms attached to the central atom ever be polar? For example.. I know this isn't true but let's say the molecule SO2Cl2 had square planar geometry with S as the central atom.. it wouldn't be polar right?

[maccha]

no wait.. it would be polar?

[cth]

It depends on the conformation of the substituants.

Let's take an example: cisplatin Pt(Cl)₂(NH₃)₂ http://en.wikipedia.org/wiki/Cisplatin

If the two chlorine atoms are next to each other (as it is for cisplatin), then the complex is polar. The Cl atoms draw some of the electrons towards them  there is unbalance between the charges. The complex is polar.

If the two chlorine atoms are on opposite side of the platinum, then the complex is not polarized. The effect from one Cl is balanced by the effect from the other Cl. There is symmetry between the electrical charges. And similarly for the effects from the nitrogen atoms.