The coordination number of a central metal atom in a coordination compound refers to the number of ligand donor atoms bonded directly to the metal. In the compound [Fe(C2O4)3]3-, the ligand oxalate (C2O4) is bidentate, meaning it can form two bonds with the metal atom. Since there are three oxalate ligands, each contributing two donor atoms bound to the iron (Fe), the total coordination number for Fe is calculated as follows:
Ligand Type
Number of Ligands
Donor Atoms Per Ligand
Total Donor Atoms
Oxalate (C2O4)
3
2
3 × 2 = 6
Hence, coordination number of Fe in [Fe(C2O4)3]3- is 6.