Which of the following is an unsymmetric bidentate ligand?

Glycinate ion

The correct answer is option 4. Glycinate ion.

An unsymmetric bidentate ligand is a type of ligand that can coordinate to a metal center using two donor atoms, but the two donor atoms are not of the same element or type. Let's examine the given options to determine which one is an unsymmetric bidentate ligand:

(1) Oxalate ion (\(C_2O_4^{2-}\)) - Oxalate ion is a symmetric bidentate ligand. It has two oxygen atoms as donor atoms, and both oxygen atoms are of the same type.

(2) Ethylenediamine (\(NH_2CH_2CH_2NH_2\)) - Ethylenediamine is a symmetric bidentate ligand. It has two nitrogen atoms as donor atoms, and both nitrogen atoms are of the same type.

(3) Acetylacetone (\(CH_3COCH_2COCH_3\)) - Acetylacetone is a symmetric bidentate ligand. It has two oxygen atoms as donor atoms, and both oxygen atoms are of the same type.

(4) Glycinate ion (\(NH_2CH_2COO^-\)) - Glycinate ion is an unsymmetric bidentate ligand. It has two donor atoms, one nitrogen atom, and one oxygen atom. The nitrogen atom and the oxygen atom are not of the same type, making it unsymmetric.

So, the correct answer is: (4) Glycinate ion