One of the notable features of the transition element is the great variety of oxidation states it may show in its compounds. The elements which give the greatest number of oxidation states occur in or near the middle of the series. Manganese, for example exhibits all the oxidation states from +2 to +7. The lesser number of oxidation states at the extreme ends is either due to the loss or sharing of a few electrons (Sc, Ti) or too many d electrons of higher valence. Early in the first series scandium (II) is virtually unknown and titanium (IV) which is more stable than Ti (III) or Ti (II). On the other end, the only oxidation state of zinc is +2.

Ambidentate ligand among the following is

1. \(NCS\)
2. \(C_2O_4^{2-}\)
3. \(SCN\)
4. \(N_2NCH_2CH_2NH_2\)
5. \(NO_2\)

Choose the correct answers from the options given below:

A, C and E only

The correct answer is 1. A, C and E only.

An ambidentate ligand is a ligand that can bind to a central metal atom through two or more different donor atoms. In the given options, only \(NCS, SCN,\) and \(NO_2\) are ambidentate ligands.

• \(NCS\) can bind to a metal atom through either the nitrogen atom \((N)\) or the sulphur atom \((S)\).
• \(SCN\) can bind to a metal atom through either the sulphur atom \((S)\) or the nitrogen atom \((N)\).
• \(NO_2\) can bind to a metal atom through either the nitrogen atom \((N)\) or the oxygen atom \((O)\).

\(C_2O_4^{2-}\) is a bidentate ligand, but it is not ambidentate because it can only bind to a metal atom through one set of donor atoms (the two oxygen atoms).

\(H_2NCH_2CH_2NH_2\) is a chelating ligand, but it is not ambidentate because it can only bind to a metal atom through one set of donor atoms (the two nitrogen atoms).

Therefore, the only ambidentate ligands among the given options are \(NCS, SCN,\) and \(NO_2\).