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Lecture

Coordination Chemistry: Ligand Interactions

In course

CH-222: Coordination chemistry

Fundamental knowledge of coordination compounds. ...

Description

This lecture covers the principles of coordination chemistry, focusing on ligand interactions with metal ions. Topics include the stability of complexes, Irving Williams Series, Hard Soft Acid Base Theory, and the influence of ligand size and charge on complex stability.

Instructor

Wendy Lee Queen

Official source

Ontological neighbourhood

Chemistry

Inorganic chemistry: Coordination chemistry

Related concepts (32)

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".

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.

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.

Coordination sphere

In coordination chemistry, the first coordination sphere refers to the array of molecules and ions (the ligands) directly attached to the central metal atom. The second coordination sphere consists of molecules and ions that attached in various ways to the first coordination sphere. The first coordination sphere refers to the molecules that are attached directly to the metal. The interactions between the first and second coordination spheres usually involve hydrogen-bonding. For charged complexes, ion pairing is important.

Tetradentate ligand

In chemistry, tetradentate ligands are ligands that bind four donor atoms to a central atom to form a coordination complex. This number of donor atoms that bind is called denticity and is a method of classifying ligands. Tetradentate ligands are common in nature in the form of chlorophyll, which has a core ligand called chlorin, and heme, which has a core ligand called porphyrin. They are responsible for the colour observed in plants and humans. Phthalocyanine is an artificial macrocyclic tetradentate ligand that is used to make blue and green pigments.

Related lectures (31)

Coordination Chemistry: Ligands and Geometries

Covers coordination numbers, common ligands, and preferred geometries in coordination chemistry, emphasizing the spatial distribution between ligands and the role of d⁸ electron configurations.

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.

Preparation & Stabilities of Complexes

Covers the preparation and stabilities of complexes, including redox reactions, substitution, and catalytic reactions.

Coordination Chemistry: High Spin Complexes and Ligands