What is the geometry of cis-diamminedichloroplatinum(II)?
From the name, the formula is
WHAT KIND OF MOLECULAR GEOMETRY IS THIS?
For a four-coordinate metal-ligand complex, we can have either a tetrahedral, square planar, or see-saw geometry.
We know it is square planar because we are given the cis configuration, which is not possible in tetrahedral or see-saw geometries. Thus, it is fairly easy to figure out how to draw cis vs. trans from there.
HOW TO DRAW CIS?
Cis means same side, while trans means opposite side.
Therefore, two identical ligands will be
It's a planar molecule, so feel free to draw it in the plane of the paper.
If we were not given the configuration, however, then consider the following.
DETERMINING THE GENERAL LIGAND FIELD SPLITTING ENERGY (LARGE? SMALL?)
Platinum, being a
That decreases the coulombic repulsion energy, which we will call
There also exists an exchange energy
These are such that the pairing energy
#color(blue)(Pi = Pi_c + Pi_e)#
Normally square planar complexes have more repulsions than tetrahedral complexes due to their smaller equatorial angles (and thus more closely spaced the ligand bonding electron pairs), so they tend to be low spin, as shown below for a
In addition, we know that see-saw complexes do not have cis/trans configurations.
Hence, we can still predict this complex to be square planar.