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.
Tetradentate ligands can be classified by the topology of the connections between donor atoms. Common forms are linear (also called sequential), ring or tripodal. A tetrapodal ligand that is also tetradentate has four legs with donor atoms and a bridgehead that is not a donor. Upon binding with a central atom, there are several arrangements possible (known as geometric isomers).
A linear tetradentate ligand has the four donor atoms in a line and each subsequent donor is connected by one of three bridges. Such a ligand bound to a metal in tetrahedral coordination can only connect in one way, though if the ligand is unsymmetrical then there are two chiral arrangements. A linear tetradentate ligand can also bind to a metal in square planar coordination in one way, where anticlockwise or clockwise arrangements are equivalent.
A linear tetradentate ligand has its donor atoms arranged along or in a chain so that each adjacent donor atom has to be adjacent on the central atom. This arrangement leads to three stereochemical outcomes, and the four donor groups can be co-equatorial. This geometry is called trans because the remaining unoccupied positions on the octahedron are mutually trans (opposite). When the two internal donor atoms are pyramidal (such as the secondary amines in trien or EDDA), two diastereomers for the trans arrangement are determined by the relative stereochemistry of these centers. Typically these donors are mutually trans, resulting in a chiral complex of C2-symmetric complexes.
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
Learn about how the quality of water is a direct result of complex bio-geo-chemical interactions, and about how to use these processes to mitigate water quality issues.
Presentation of selected signalling pathways with emphasis on both the mechanism of action of the molecules involved, molecular interactions and the role of their spatio-temporal organization within t
Explores crystal field theory, focusing on square planar complexes and the spectrochemical series.
Covers coordination numbers, common ligands, and preferred geometries in coordination chemistry, emphasizing the spatial distribution between ligands and the role of d⁸ electron configurations.
Covers the reactivity towards oxidation and product formation after ligand loss.
A dinuclear metal-organic cage with four acrylate side chains was prepared by self-assembly. Precipitation polymerization of the cage with N-isopropylacrylamide yielded a thermoresponsive nanogel. The host properties of the cage were retained within the ge ...
2024
The combination of palladium salts and bipyridyl ligands can lead to the formation of a large variety of coordination complexes, with different shapes and sizes, displaying a very versatile host-guest chemistry. Increasing their structural complexity remai ...
G-protein-coupled receptors (GPCRs) are key regulators of human physiology and are the targets of many small-molecule research compounds and therapeutic drugs. While most of these ligands bind to their target GPCR with high affinity, selectivity is often l ...