Question

List examples of positive and negative ligands.

Answer 1

Ligands:

• The ions or molecules which surround a metal ion or metal atom are called ligands which are attached to a central metal atom or central metal ion by a co-ordinate bond.
• In order to be a ligand, any molecule or ion should possess at least one lone pair or a bond pair that can be shared with a central metal ion.
• The ionic ligands can be divided into the following two categories: Negative ligands and Positive ligands

Negative ligands:

• Ligands that carry a negative charge or anion and usually contain suffixes like ‘ite’ or ‘ate’ which are further replaced by ‘O’ are called negative ligands.
• List of examples for Negative ligands:$\mathrm{Nitrosyl}\left(\mathrm{NO}\right),$$\mathrm{Chloride}\left({\mathrm{Cl}}^{-}\right),$$\mathrm{Isothiocyanate}(\mathrm{N}=\mathrm{C}={\mathrm{S}}^{-}),$$\mathrm{Superoxide}\left({\mathrm{O}}^{2–}\right),$etc.

Positive ligand:

• The ligand ligands that carry a positive charge or cation and usually contain suffixes like ‘ium’ is called the positive ligand.
• List of examples of positive ligands:$\mathrm{\eta }7-{\mathrm{C}}_7{{\mathrm{H}}^{+}}_7\mathrm{Cycloheptatrienyl}\left(\mathrm{heptahaptocycloheptatrienyl}\right)$,$\mathrm{N}{\mathrm{H}}_2\mathrm{N}{{\mathrm{H}}_3}^{+}\left(\mathrm{hydrazinium}\right)$and
  $\mathrm{N}{{\mathrm{O}}_2}^{+}\left(\mathrm{nitronium}\right)$etc.

Hence, these are the given list of positive and negative ligands.