Sulfido refers to the ligand species . There is only one donor atom present in this ligand which is sulfur.Shriver and Atkins. Inorganic Chemistry (5th Edition). W. H. Freeman and Company, New York, 2010, pp 201. It also refers to the ligand or functional group , which is a sulfur atom bonded to the rest of molecule by a single bond, and has a charge of −1.
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