Why is octahedral and square bipyramidal

There is one pair of electrons that has taken the place of one of the atoms and because these electrons are now present, it gives the molecule a distict new look. There are five bonding pairs and one electron pair. The atoms have to arrange themselves in the most stable form possible, not only limiting the bond-pair to bond-pair interaction, but also limiting the bond-pair to electron-pair interaction.

The easiest way to visualize what this molecule looks like to visualize the x, y, and z coordinate plane again, but this time remove what would be considered the negative y coordinate axis and put a pair of lone pair electrons in its place.

The molecule is still considered apart of the octahedral species because it still satisfies the 6 atom requirement, but in terms of its shape, the electrons effect the shape.

This allows it to have its new shape. If you actually exclude those electrons and lay the molecule on the surface, you can see that it looks like a three dimensional pyramid with a square base. Again all the atoms and electron pair are 90 degrees apart from each other and from the atom directly across and opposite from it. Here is what a square pyramidal would look like:. Square Pyramidal 5 bond pairs and 1 electron pair. The last of the octahedral species is known as a square planar.

This molecule resembles both of the previous molecules, but more similarly resembles a square pyramidal. It still has many of the characteristics of a square pyramidal, but what makes it different is that rather than having only one pair of electrons replacing the position of an atom, there are two pairs of electrons that are replacing the position of two atoms.

To visualize what this molecule looks like, we refer back to the x, y, and z coordinate system, the only difference is this time we are taking away the entire y coordinate, and replacing it with electrons on what would be the positive y coordinate axis as well as placing a pair of electrons in what would be considered the negative y coordinate axis.

The reason for this arrangement goes back to having the molecule arrange itself in the most stable form possible limiting interactions between bond-pair to bond-pair, bond-pair to electron-pair, and electron-pair to electron-pair.

If you try visualizing what this would look like, it almost resembles a three-dimensional "X" with two pairs of lone electrons.

Because the lone pairs of electrons are still present, that allows this molecule to still be considered an octahedral due to the fact that it still meets the requirements of being surrounded by 6 atoms or groups. In regards to its shape the electron pairs cause repulsion, thus allowing it to have its new shape.

The atoms and electrons are still 90 degrees apart from eachother and degrees from the atom directly across and opposite from it. Here is what a square planar would look like:.

Square Planar 4 bond pairs and 2 electron pairs. Rename to desired sub-topic. You can delete the header for this section and place your own related to the topic. Remember to hyperlink your module to other modules via the link button on the editor toolbar. What causes the three different octahedral species to arrange the way they do?

What conditions must be met? Can two seperate electron-pair stand at 90 degrees apart from eachother? Give one example of a molecules that would fall into the category of a octehedral, square pyramidal, and square planar. The molecules take the arrangment they do due to trying to arrange themselves in the most stable structure possible limiting the interaction between bond-pair and electron-pair interaction.

As long as these conditions can be met, it is possible for the structure to not only exist, but remain stable. This again goes back to satisfying the conditions of keeping the molecule as stable as possible by limiting lone-pair to lone -pair interaction as well as same sign interaction. Because electrons hold the same kind of charge, they can not be near eachother due to same charge repulsion and so they need to be as far away as possible from eachother so that the molecule may be stable.

Molecules that would fall into the category of triganol planar based on their molecular geometry would be SF6, a molecule that falls into the category of a square pyramidal would be BrF5 and one molecule that would fall into a category of a square planar would be [AuCl2]-.

Introduction To be able to understand and distinguish the difference between the three types of octahedral species and how they differ from one molecule to the next, it is essential to try to visualize shapes geometrically and in 3D.

Here is basic, but clear example of what an octahedral looks like: Octahedral 6 bond pairs and 0 electron pairs The next molecule that we will examine is known as a square pyramidal. Notable examples include the anticancer drugs cisplatin [PtCl 2 NH 3 2 ] and carboplatin. In principle, square planar geometry can be achieved by flattening a tetrahedron.

As such, the interconversion of tetrahedral and square planar geometries provides a pathway for the isomerization of tetrahedral compounds. The removal of a pair of ligands from the z-axis of an octahedron leaves four ligands in the x-y plane. Therefore, the crystal field splitting diagram for square planar geometry can be derived from the octahedral diagram. The removal of the two ligands stabilizes the d z2 level, leaving the d x2 -y 2 level as the most destabilized.

Consequently, the d x2 -y 2 remains unoccupied in complexes of metals with the d 8 configuration. These compounds typically have sixteen valence electrons eight from ligands, eight from the metal.

Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:. Skip to main content. Transition Metals. Search for:. Tetrahedral and Square Planar Complexes. Learning Objective Discuss the d-orbital degeneracy of square planar and tetrahedral metal complexes.

Key Points In tetrahedral molecular geometry, a central atom is located at the center of four substituents, which form the corners of a tetrahedron. Tetrahedral geometry is common for complexes where the metal has d 0 or d 10 electron configuration.