Question

What is the co-ordination number of metal in [Fe(C$_2$O$_4$)$_3$]$^{3-}$?

• A. Two
• B. Three
• C. Six
• D. Four

Answer 1

The Correct Option is C

The coordination number quantifies the number of ligand donor atoms directly attached to a metal ion within a coordination complex. Consider the complex [Fe(C₂O₄)₃]^3-. The ligand present is oxalate (C₂O₄^2-), which functions as a bidentate ligand, meaning it establishes two bonds with the central metal ion.

Calculation:

1. The complex features three oxalate ligands: [Fe(C₂O₄)₃]^3-.
2. Each individual oxalate ligand contributes two coordination sites.
3. Consequently, the aggregate number of coordination sites amounts to 3 ligands multiplied by 2 donor sites per ligand, equaling 6.

Therefore, the iron (Fe) ion in this complex exhibits a coordination number of six.