Coordination Number of Fe in [Fe(NH3)2(CN)4]^-
The coordination number of a metal ion is the number of ligands attached to it. In the given compound, [Fe(NH3)2(CN)4]^-, Fe is the central metal ion to which four CN^- ions and two NH3 ligands are attached. Hence, the coordination number of Fe in [Fe(NH3)2(CN)4]^- is 6.
Explanation
There are various factors that determine the coordination number of a metal ion. In general, the coordination number of a metal ion depends on:
- The size of the metal ion
- The size of the ligands
- The charge on the metal ion
- The charge on the ligands
- The geometry of the complex
In the given compound, Fe has a charge of +2, and each CN^- ion has a charge of -1. Each NH3 ligand has a neutral charge. The size of Fe is relatively small, and the size of both CN^- and NH3 ligands is also small. The geometry of the complex is octahedral, with four CN^- ions and two NH3 ligands arranged around the central Fe ion.
Since there are six ligands attached to the Fe ion, the coordination number of Fe in [Fe(NH3)2(CN)4]^- is 6.
Conclusion
The coordination number of Fe in [Fe(NH3)2(CN)4]^- is 6. This is because there are six ligands attached to the Fe ion, consisting of four CN^- ions and two NH3 ligands. The size of Fe and the ligands, the charge on the metal ion and the ligands, and the geometry of the complex all contribute to determining the coordination number of the metal ion.