Johnsonin

Johnsonin is a fictional chemical compound used in chemistry education to illustrate coordination chemistry, ligand field theory, and molecular nomenclature. It does not correspond to any known substance in standard databases, and no experimental data support its real existence.

In the standard hypothetical description, Johnsonin is a six-coordinate octahedral complex of a transition metal M bound to six ligands L, written as [M(L)6]2+ in its common oxidation state. The ligands are typically assumed to be neutral or monoanionic and chosen to produce clear crystal field splitting, allowing discussion of high-spin and low-spin configurations.

Synthesis is described in textbooks as a sequence where a metal salt MX2 reacts with six equivalents of a multidentate ligand under controlled solvent conditions to form the octahedral complex, with byproducts such as counterions balancing charge.

Properties and behavior: color changes with ligand field strength, UV-visible spectra illustrate d-d transitions, and reactivity toward substitution reactions can be used to discuss kinetics. Johnsonin serves as a didactic tool rather than a practical compound.

Etymology and usage: The name combines “Johnson” with a suffix to indicate the fictional nature, often attributed to a pedagogical scenario created by educators.

Notes: Johnsonin is not real; it is a pedagogical construct used to demonstrate concepts in coordination chemistry.