Write a formula for following coordination compound: sodium tris(ethylenediamine)oxalatonickelate(I).

• A. Na₂[Ni(en)₃CO₂]
• B. Na[Ni(NH₃)₃CO₂]
• C. Na[Ni(en)₃C₂O₄]
• D. Na[Ni(NH₃)₃C₂O₄]

Answer: (C)

Verified step by step guidance

1. Identify the central metal ion in the coordination compound. In this case, it is nickel (Ni).
2. Determine the ligands attached to the central metal ion. The ligands are ethylenediamine (en) and oxalate (C2O4).
3. Count the number of each type of ligand. The compound has three ethylenediamine ligands and one oxalate ligand.
4. Write the formula for the complex ion, placing the ligands around the central metal ion. The complex ion is [Ni(en)3C2O4].
5. Add the counter ion to balance the charge of the complex ion. Sodium (Na) is the counter ion, resulting in the formula Na[Ni(en)3C2O4].