Concept:Anionic ligands are negatively charged species that donate electron pairs to a central metal ion.
Explanation:Isothiocyanato is
NCS− or
SCN−, so it carries a negative charge.
Hence, it is an anionic ligand.
Ammine is
NH3​, which is a neutral molecule.
Aqua is
H2​O, which is also neutral.
Ethylenediamine is
H2​NCH2​CH2​NH2​, and it is a neutral bidentate ligand.
Therefore, only isothiocyanato is anionic among the given options.
Answer:Option A – Isothiocyanato.