Question

Given the list of ligands and their corresponding names, choose the pair that disagree.
A. $OH$, hydroxo
B. $C{N}^{-}$, cyanide
C. $C{l}^{-}$, chloro
D. $H_{2}O$, aqua

Answer 1

Hint: The ions or molecules capable of donating at least a pair of electrons to the central metal atom or ion to form a coordination complex is called a ligand. The word ligand is derived from Latin, which means “tie or bind”. Ligands can be anions, cations, and neutral molecules and they act as Lewis bases (donate electron pairs) and central metal atoms viewed as Lewis acid (electron pair acceptor). The bonding nature between metal to ligand varies from the covalent bond to the ionic bond.

Complete step by step answer:
The first option is OH. The corresponding name of hydroxide ion or $O{H}^{-}$ is hydroxo.
Second option is $C{N}^{-}$. The corresponding name of cyanide ion or $C{N}^{-}$ is cyano.
Third option is $C{l}^{-}$. The corresponding name of halide ion or $C{l}^{-}$ ion is chloro.
Fourth option is $H_{2}O$. The corresponding name of the water ligand is aqua.
After discussing we can conclude that the second pair of the ligand and its corresponding name is wrong.

Thus, the correct option for these questions is B.

Note: Types of ligands.
Monodentate or Unidentate ligands: If a ligand contains one donor atoms, it is a bidentate or monodentate ligand. Example: Water, ammonia, etc.
Polydentate ligands: When ligands have two or more donor atoms that may simultaneously co-ordinate to the central metal atom, then it is called a polydentate ligand. Examples: Ethylenediamine.
Ambidentate ligands: The ligands which have two or more different donor sites but only one of these is attached to a single metal atom at a given time are called ambidentate ligands. Example: Thiocyanate $\left(SC{N}^{-}\right)$ with $\left(M\leftarrow SC{N}^{-}\right)$ and Isothiocyanato $\left(NC{S}^{-}\right)$ with $\left(M\leftarrow NC{S}^{-}\right)$ linkage.
Bridging ligands: A bridging ligand is defined as one that can simultaneously bond itself to more than one metal ion. $O{H}^{-}$, $C{l}^{-}$,$N{H}^{-}$ etc. can function both as monodentate and bridging ligands.