Linkage Isomerism and Flexidentate Ligands

Linkage isomerism is a phenomenon in which a ligand can attach to a central metal ion through different atoms. In other words, the ligand can exist in two or more isomeric forms depending on the nature of the atom that is attached to the metal ion. The common example of linkage isomerism is the nitro group, which can attach to the metal ion through nitrogen or oxygen atoms.

On the other hand, a flexidentate ligand is a ligand that can attach to the metal ion through different atoms at different times. For example, ethylenediamine is a flexidentate ligand as it can attach to the metal ion through either of its two nitrogen atoms.

Answer

Out of the given options, the ligand that can show linkage isomerism and act as a flexidentate ligand is NO2 (nitro group). This is because the nitro group can attach to the metal ion through either nitrogen or oxygen atoms, exhibiting linkage isomerism. Additionally, it can act as a flexidentate ligand by binding to the metal ion through one nitrogen atom first and then the other nitrogen atom at a later time.

Option A (CNS) can show linkage isomerism but is not a flexidentate ligand as it can only attach to the metal ion through the nitrogen atom. Option C (CN) can also show linkage isomerism, but it is not a flexidentate ligand as it can only attach to the metal ion through the carbon atom. Option D (NO3) cannot show linkage isomerism as all three oxygen atoms are equivalent and cannot attach to the metal ion through different atoms.