Alfred Werner

Alfred Werner (1866–1919) was a Swiss chemist who established modern coordination theory, explaining the structures and bonding of metal complexes. He received the 1913 Nobel Prize in Chemistry.

Coordination compound: A compound containing a central metal atom or ion bonded to surrounding molecules or ions called ligands. These compounds were the puzzling substances Werner’s theory set out to explain.
Primary valence: In Werner’s theory, the ionizable charge of a metal complex, corresponding broadly to its oxidation state. It explained which counterions separated from a complex in solution.
Hexol: A cobalt(III) coordination compound whose preparation and optical activity became a landmark in Werner’s research. Werner’s synthesis of an optically active inorganic complex challenged the view that such activity required carbon.
Arthur Hantzsch: A German chemist known for research in organic chemistry and for early work on stereochemistry. Werner collaborated with Hantzsch on stereochemical questions during his early career.
Inorganic chemistry: The study of chemical compounds and reactions not primarily based on carbon–hydrogen frameworks. Werner’s theory transformed the understanding of complex inorganic compounds.
Ligand: An ion or molecule that donates an electron pair to a central atom, commonly a metal, to form a coordination bond. Ligands occupy positions around metal centers in the compounds Werner studied.
Secondary valence: In Werner’s theory, the fixed number of groups directly coordinated to a metal center. It accounted for the metal’s coordination number and the arrangement of attached groups.
Cobalt(III) hexammine chloride: A coordination salt containing the complex cation [Co(NH₃)₆]³⁺ and three chloride counterions. Its ionization behavior illustrated Werner’s distinction between coordinated groups and counterions.
University of Zurich: A public research university in Zurich, Switzerland, founded in 1833. Werner conducted his influential research and taught chemistry there.
Coordination chemistry: The study of compounds in which metal centers bind surrounding ligands. Werner established the structural principles that organize this field.

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