Identify the complex formed by $\mathrm{Ni}^{2+}$ with dimethylglyoxime (DMG)

Nickel(II) reacts with dimethylglyoxime to form the well-known neutral chelate complex: $\mathrm{Ni(dmgH)_2}$ where each dimethylglyoxime ligand loses one proton and coordinates as a monoanionic bidentate ligand.

Find the molecular formula of dimethylglyoxime

Dimethylglyoxime has the structure: $\mathrm{CH_3-C(=NOH)-C(=NOH)-CH_3}$ Its molecular formula is: $\mathrm{C_4H_8N_2O_2}$

So, one DMG molecule contains 8 hydrogen atoms.

Hydrogen atoms in the coordinated ligand

In the nickel complex, each DMG loses one acidic hydrogen during complex formation. Therefore, each coordinated ligand $\mathrm{dmgH^-}$ contains: $8 - 1 = 7 \text{ H atoms}$

Total hydrogen atoms in the complex

Since the complex is $\mathrm{Ni(dmgH)_2}$, it contains two such ligands: $2 \times 7 = 14$

Final answer

The complex contains: $\boxed{14}$

Comparison with stored correct answer

Stored correct answer = $14$

Our derived answer matches it.