Would you expect the complex [Co (en) 3]Cl3 to have any unpaired electrons? Any isomers?

Answer: zero unpaired electrons

And exist as geometrical and optical isomers

Explanation:

Since here oxidation no of Central atom Co is + 3 and Electronic configuration=[Ar]3d6

And en is a strong field ligand hence pairing of Electrons involved and it results zero unpaired electrons.

Cis isomer exists as active d and l isomers while trans isomer is optically inactive.