Chelating Ligand:

A chelating ligand is a type of ligand that can form multiple coordinate bonds with a single metal ion. This results in a more stable complex due to the formation of a ring structure between the metal ion and the ligand. Chelating ligands are commonly used in coordination chemistry and have important biological applications.

DMG as a Chelating Ligand:

DMG or dimethylglyoxime is a bidentate ligand, which means it can form two coordinate bonds with a metal ion. It contains two nitrogen atoms that can donate lone pairs of electrons to the metal ion, forming a stable complex. DMG is commonly used as a chelating ligand in analytical chemistry to detect the presence of metal ions, particularly nickel.

Other Ligands:

Cl-, H2O, and OH- are not chelating ligands as they can only form one coordinate bond with a metal ion. Cl- and OH- are monodentate ligands, meaning they can only donate one lone pair of electrons to the metal ion. H2O is a weaker ligand than DMG and can only form one coordinate bond with a metal ion.

Conclusion:

In conclusion, DMG is a chelating ligand as it can form multiple coordinate bonds with a single metal ion, resulting in a more stable complex. Cl-, H2O, and OH- are not chelating ligands as they can only form one coordinate bond with a metal ion.