In this article, we will be talking about the D orbital configurations in which the lobes of the D orbital point directly at the ligands in a square-planar crystal field. How does one determine if the lobes of the D orbital point directly at the ligands?
The D molecular orbital is typically defined as having two angular orbitals and one radial orbital, which combine to form three spatial orbitals. These are referred to as d z 2 , d xy , and d x 2−y 2 .
In this article, we will be focusing on just the d z 2 angular orbital and the d xy hybridization Orbital(s). How do we know which ones these are? We will tell you!
After reading this article, you will know how to identify for which D orbitals the lobes point directly at the ligands in a square-planar crystal field.
Identify the d orbitals that contain lobe directions pointing directly at the ligands
Now that you know which d orbitals have lobes pointing in the direction of the ligands, you must identify which d orbitals contain a lobe in each direction.
There are two requirements for an orbital to be able to contain lobes pointing directly at the ligands. The first requirement is that the orbital must belong to a set of lower energy orbitals, specifically 2s, 2p, and 3s.
The second requirement is that the orbital must belong to a set of symmetric orbitals. Asymmetric orbitals do not contain a reflection across some plane, so all of its points (electrons) are different.
Converting asymmetric orbitals into symmetric ones is easy: Just merge identical points together! Doing so will create new points, but will not change the number of points in each orbital.
Understand why this happens
Now, let’s talk about why this happens. When the d orbitals point directly at the ligands in a square-planar crystal field, the electron density on the n ligand is zero.
When the electron density on the n ligand is zero, then there is no potential for that electron to be absorbed by the metal. When there is no potential for absorption, then there is no interaction between the ligand and metal.
When there is no interaction between the ligand and metal, then there is no coordination of the ligand to the metal. When coordination does not occur, then it cannot form a crystal lattice with the metal. When it cannot form a crystal lattice with the metal, then it will not be part of the complex.
Know what this means in terms of chemical reactivity
Once you’ve determined the configuration of your d-orbitals in your square-planar complex, you can determine the ligands that can be attached to it.
If all of the lobes point directly at the ligands, then the complex is said to be solvophobic. This means that it does not like to attach other molecules to it. It is relatively stable and does not readily react with other compounds.
If only one lone lobe points directly at the ligand, then the complex is said to be solvophilic. This means that it likes to attach molecules to it. It is relatively reactive and readily reacts with other compounds.
The remaining cases are considered amphiphilic, which means that there are some lobes that point directly at the ligand and some that do not. These are typically more reactive than amphiphilic or non-amphiphilic complexes.
Use your knowledge to answer related questions
Now that you know how to identify square-planar d orbitals, you can use your knowledge in several ways. You can answer questions about which d orbitals point directly at the ligands in a square-planar crystal field, you can answer questions about what happens to the lobes of the d orbitals in a non-square-planar crystal field, and you can answer questions about whether or not lone electron pairs occupy these orbitals.
Questions about which d orbitals point directly at the ligands in a square-planar crystal field are easy to answer. Any d orbital that is squared off at the bottom is one that points directly at the ligands. These are the 2s, 2pz, 3s, and 3pz d orbitals. The other ones are rounded or oblong, so they do not point directly at the ligand atoms.
Questions about what happens to the lobes of the d orbital in a non-square-planar crystal field are also easy to answer. If there is an sigma bond between two adjacent atoms within one of the lobes of an orbital, then there is a ninety degree rotation of that lobe. This happens because of mutual repulsion between the electron density and the overlapping atom.
Test your knowledge by taking a quiz
Now it’s time to put your knowledge to the test. Take a quiz on the material you just read to make sure you understand the information.
Quiz: For Which D Orbital(s) Do the Lobes Point Directly at the Ligands in a Square-Planar Crystal Field?
Now that you have read this article, you should be able to answer this quiz question.
Question: In which d orbital(s) do the lobes point directly at the ligands in a square-planar crystal field?
Answer: Only in d z2 orbitals do the lobes point directly at the ligands in a square-planar crystal field. All other d orbitals have orbital symmetry, meaning that there is some direction in which all of the electrons are located and all other directions are different. This makes it so that some of the lobes point toward the ligand and some do not.
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