Hi,
How do you know how many ligands a metal ion needs to form a complex ion?
So for example, with (Fe(H20)6)2+, how am I supposed to know that the Fe needs 6 H20's, rather than 4?
Thank you!
http://chem.libretexts.org/Core/Inorganic_Chemistry/Coordination_Chemistry/Properties_of_Coordination_Compounds/What_is_a_Complex_Ion%3F
Start with the d level electrons in iron.
To determine the number of ligands a metal ion needs to form a complex ion, you need to consider a few factors. These factors include the coordination number of the metal ion, the electronic configuration of the metal ion, and the nature of the ligands.
1. Coordination number: The coordination number refers to the number of atoms or groups directly attached to the central metal ion. It provides information about how many ligands can bind to the metal ion. Common coordination numbers include 2, 4, 6, and 8.
2. Electronic configuration: The valence electron configuration of the metal ion influences its reactivity and ability to form complexes. The metal ion tends to form complexes by sharing or donating its valence electrons to the ligands to achieve a more stable electron configuration.
3. Ligand nature: Different ligands have different abilities to bind to metal ions. Some ligands are strong field ligands, while others are weak field ligands. Strong field ligands exert a stronger influence on the metal ion, causing a greater distortion in its electron configuration. This often leads to a lower coordination number. Weak field ligands have a weaker influence and may result in a higher coordination number.
In the case of (Fe(H2O)6)2+, you are dealing with the hydrated form of iron(II). Iron(II) has a d6 electron configuration (3d6, 4s0). It forms a complex with six water molecules as ligands. The coordination number of 6 is commonly observed for metals with d6 electron configurations, as water acts as a weak field ligand for iron(II).
In summary, to determine the number of ligands a metal ion needs to form a complex, you consider the coordination number, the electronic configuration of the metal ion, and the nature of the ligands. It is useful to study the properties and behavior of different metal ions with specific ligands to gain a deeper understanding of complex formation.