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Lecture

Crystal Field Theory: Octahedral and Tetragonal Distortions

In course

CH-222: Coordination chemistry

Fundamental knowledge of coordination compounds. ...

Description

This lecture delves into Crystal Field Theory, focusing on the impact of ligands on d orbitals in octahedral and tetrahedral environments. The instructor explains the energy splitting of d orbitals, the crystal field stabilization energy, and the effects of axial elongation and compression on the orbital diagrams.

Instructor

Wendy Lee Queen

Official source

Ontological neighbourhood

Chemistry

Inorganic chemistry: Coordination chemistry

Related concepts (18)

Crystal field theory

In molecular physics, crystal field theory (CFT) describes the breaking of degeneracies of electron orbital states, usually d or f orbitals, due to a static electric field produced by a surrounding charge distribution (anion neighbors). This theory has been used to describe various spectroscopies of transition metal coordination complexes, in particular optical spectra (colors). CFT successfully accounts for some magnetic properties, colors, hydration enthalpies, and spinel structures of transition metal complexes, but it does not attempt to describe bonding.

Ligand field theory

Ligand field theory (LFT) describes the bonding, orbital arrangement, and other characteristics of coordination complexes. It represents an application of molecular orbital theory to transition metal complexes. A transition metal ion has nine valence atomic orbitals - consisting of five nd, one (n+1)s, and three (n+1)p orbitals. These orbitals are of appropriate energy to form bonding interaction with ligands. The LFT analysis is highly dependent on the geometry of the complex, but most explanations begin by describing octahedral complexes, where six ligands coordinate to the metal.

Spectrochemical series

A spectrochemical series is a list of ligands ordered by ligand "strength", and a list of metal ions based on oxidation number, group and element. For a metal ion, the ligands modify the difference in energy Δ between the d orbitals, called the ligand-field splitting parameter in ligand field theory, or the crystal-field splitting parameter in crystal field theory. The splitting parameter is reflected in the ion's electronic and magnetic properties such as its spin state, and optical properties such as its color and absorption spectrum.

Coordination complex

A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the coordination centre, and a surrounding array of bound molecules or ions, that are in turn known as ligands or complexing agents. Many metal-containing compounds, especially those that include transition metals (elements like titanium that belong to the periodic table's d-block), are coordination complexes. Coordination complexes are so pervasive that their structures and reactions are described in many ways, sometimes confusingly.

Ligand

In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands".

Related lectures (32)

Crystal Field Theory: Spectrochemical Series

Explores the Spectrochemical Series for metals and ligands, Crystal Field Splitting, Jahn-Teller distortion, and bonding interactions in coordination compounds.

Ligand Field Theory: Octahedral Coordination Complexes

Covers ligand field theory for octahedral coordination complexes with pure sigma donors.

Pi-Donor and P-Acceptor Ligands

Explores the impact of pi-donor and p-acceptor ligands on ligand field splitting diagrams and metal orbitals in coordination complexes.

Crystal Field Theory: Square Planar Complexes

Explores crystal field theory, focusing on square planar complexes and the spectrochemical series.

Ligand Field Theory