Ligandide

Ligandide is a term that appears sporadically in discussions of coordination chemistry and organometallic chemistry, but it is not a standard or widely adopted term in formal nomenclature. In many sources, the word is used informally to describe a concept related to ligands bound to a central metal atom or to a ligand-derived fragment within a metal complex. Because there is no agreed-upon definition, the precise meaning of ligandide varies among authors and contexts.

Common interpretations include:

- The ligand environment or coordination sphere of a metal complex, i.e., the ensemble of ligands that surround and interact with the metal center, which governs the complex’s electronic structure and geometry.

- A ligand-derived fragment that remains associated with a metal center during a reaction, used in theoretical discussions or catalytic mechanisms to denote the part of the system that contributes the donor atoms and electronic effects.

- A hypothetical or pedagogical construct used to compare ligands by treating them as a distinct, quasi-molecular unit attached to a metal, sometimes in discussions of electronic effects, bite angle, and sterics.

In practice, authors typically prefer explicit description of ligands, donor atoms, and coordination geometry rather than the catch-all term ligandide. The term may appear in textbooks, lecture notes, or theoretical papers as a shorthand, but readers should consult the author’s definitions in context.

See also: coordination chemistry, ligand, metal complex, organometallic chemistry.