Ligand
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In organic chemistry, the word “ligand” is a convenience word, used to mean “atom or group of atom”.
eg. 1:
In 1, the four ligands on the chiral center are an ethyl group, a methyl group, a bromine atom, and a hydrogen atom.
eg. 2:
In 2, the ligands on the carbonyl carbon are a methyl group and a chlorine atom.