SANDWICH COMPOUND Meaning and
Definition
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A sandwich compound, also known as a coordination complex, refers to a chemical compound consisting of a central atom or ion, usually a metal, sandwiched between two organic ligands or other groups. This unique architectural arrangement gives rise to its designation as a "sandwich" compound. The central atom is typically in a low oxidation state, such as a transition metal, and acts as the filling while the ligands, composed of organic molecules, serve as the outer layers.
In a sandwich compound, the ligands embrace the central atom on both sides simultaneously, forming stable coordination bonds. This bonding occurs due to the formation of coordinate covalent bonds, where the ligands donate an electron pair to the metal atom. The coordination bonds provide a highly stable structure for the sandwich compound, ensuring its overall integrity.
Sandwich compounds have garnered significant attention in the field of inorganic chemistry due to their fascinating electronic and structural properties. They often exhibit unique reactivity and are found to be involved in various catalytic processes. The study and characterization of sandwich compounds shed light on the nature of chemical bonding, as well as many chemical phenomena occurring within coordination chemistry.
Overall, sandwich compounds represent a distinct class of coordination complexes, featuring a central atom or ion embraced by two ligands, resulting in a unique sandwich-like structure.
Etymology of SANDWICH COMPOUND
The term "sandwich compound" originated from the concept of a sandwich, where two solid pieces of bread are typically placed on either side of a filling to create a meal.
In chemistry, a "sandwich compound" refers to a specific class of compounds known as "sandwich complexes". These complexes consist of a central metal atom or ion surrounded by two organic molecules called "ligands" that act as the "bread" holding the metal ion between them.
The etymology of the term comes from the resemblance of the compound's structure to that of a sandwich. The concept was introduced in the 1950s, and the term gained popularity due to its ability to convey the complex's layered structure, with the metal ion being enclosed by the surrounding ligands.
The first known sandwich compound is ferrocene, discovered in 1951.
