2. Can you predict the complex's geometrical shape?

There are 4 possible geometrical shape of Hg2 DMPS complexes:

1.cis-Hg DMPS complexes

2. trans-Hg DMPS complexes



3. bis- Hg DMPS complexes


4. tetrakis-Hg DMPS complex

Shape 1 and 2 shows two of the four possible isomers for linear Hg coordination, shape 3 shows the true double chelate (one Hg, two DMPS), and shape 4 shows the 4:1 complex.

From the 4 possible geometrical shape of Hg2+ DMPS complexes, the exact geometrical shape of Hg2+ DMPS complexes is the bis-Hg2+ DMPS complex. This is because it is a very stable form than the 3 other possible geometrical shapes. The bond bind more stronger and makes it not easily to react with the other substances.

Besides that, the coordination number of a metal ion is often influenced by the relative sizes of the metal ion and the surrounding ligands. As the ligands gets larger, fewer ligands can coordinate to the metal ions. Hence, the geometrical shape of shape 4 is not present.

Four coordinate complexes shown above have common geometries - tetrahedral and square planar. According to figure above, the complex's geometrical shape is square planar because square planar is for transition metal ions while tetrahedral is mostly for nontransition metal. Since Hg is a transition metal, therefore the most accurate geometry is square planar.

Below is a video about predicting Molecular and Electronic Geometries using VSEPR model. Please do watch for more understanding.