Chromium(II) acetate

Chromium(II) acetate is a salt of chromium and acetic acid, commonly isolated as a hydrated dimer. Its two chromium atoms are joined by a metal–metal quadruple bond.

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Chromium–chromium quadruple bond: A metal–metal bond formed from one sigma, two pi, and one delta bonding interaction. This bond joins the dimer’s chromium atoms and gives the compound its distinctive structure.
Acetate: The conjugate base of acetic acid, with formula CH₃COO⁻. Acetate ligands bridge the chromium atoms in the commonly isolated dimer.
Organic reduction: A chemical transformation that increases electron density or lowers oxidation state in an organic molecule. Chromium(II) acetate can serve as a one-electron reducing reagent in organic reactions.
Linus Pauling: An American chemist who developed influential theories of chemical bonding and molecular structure. Pauling helped establish early interpretations of multiple bonding between metal atoms.
Molecular orbital theory: A model of chemical bonding that describes electrons as occupying orbitals spread over molecules. It explains how chromium orbitals combine to produce four bonding interactions.
Chromium: A transition metal element with atomic number 24. Its d-electron configuration enables the compound’s unusual metal–metal bond.
Reductive coupling: A reaction that joins molecular fragments while reducing their oxidation state. Chromium(II) reagents can promote carbon–carbon bond formation through reductive coupling.
F. Albert Cotton: An American inorganic chemist known for research on metal–metal bonds and cluster compounds. Cotton’s work helped make metal–metal multiple bonding a central topic in inorganic chemistry.
Antiferromagnetism: Magnetic ordering in which neighboring magnetic moments align in opposite directions. The paired chromium centers have unusually low magnetic response, tied to their bonding and electron pairing.
Oxidation state: A formal bookkeeping value describing an atom’s electron loss or gain in a compound. The chromium centers are assigned the +2 oxidation state in this salt.