Understanding the Charge on a Complex Ion: [Co(NH?)?NO?]2?

In the realm of inorganic chemistry, the understanding of complex ions and their charges is crucial for the detailed analysis and prediction of the properties of coordination compounds. One such complex ion that often causes confusion is [Co(NH?)?NO?]2?. This article aims to elucidate the charge on this complex ion and its relationship with the metal ion's oxidation state.

Introduction to the Complex Ion [Co(NH?)?NO?]2?

The complex ion [Co(NH?)?NO?]2? is a noteworthy example of a coordination complex, consisting of a central cobalt(III) ion (Co3?) coordinated with various ligands. The cobalt(III) ion is surrounded by five ammine (NH?) ligands and one nitrate (NO??) ligand, giving it a total coordination number of six.

Determining the Charge on the Complex Ion

To understand the charge on the complex ion [Co(NH?)?NO?]2?, it is essential to consider the charge contributions from both the central metal ion and the ligands around it.

Charge of the Metal Ion: Co3?

The metal ion in this complex is cobalt(III), denoted as Co3?. In the coordination chemistry, the oxidation state of cobalt is indicated by the Roman numeral in parentheses. Hence, the charge on the cobalt(III) ion is 3.

Ligand Contributions

The ligands in the complex ion can either supply electrons (anionic ligands) or have a neutral charge (neutral ligands).

In this specific complex ion, there are:

Five neutral ammine (NH?) ligands One neutral nitrate (NO??) ligand

Since both the ammine and nitrate ligands are neutral, they do not contribute any net charge to the complex ion.

Additional Counterions

Another critical aspect of the charge in this complex ion is the presence of counterions. In the case of [Co(NH?)?NO?]2?, it is described with two nitrate counterions, [NO??]2?. These nitrate ions have a charge of -1 each, making the total charge -2.

Hence, to balance the overall charge of the complex ion, the net charge of the complex is 2, as indicated by the superscript 2?. The presence of the two nitrate counterions ensures that the overall charge of the complex plus the counterions is neutral.

Charge Determination in Complex Ions

The charge on a complex ion can be determined by summing the charges of all the individual parts of the complex ion, including the central metal ion and the ligands:

Total Charge Charge of Metal Ion (Charge of Neutral Ligands) (Charge of Anionic Ligands) (Charge of Counterions)

For the complex ion [Co(NH?)?NO?]2?:

Charge of metal ion (Co3?): 3 Charge of neutral ligands (5 × NH?): 0 Charge of nitrate ligand (NO??): 0 Charge of counterions (2 × [NO??]2?): -2

Total Charge 3 0 0 (-2) 1

Therefore, the charge on the complex ion [Co(NH?)?NO?]2? is 2.

Conclusion

The charge on the complex ion [Co(NH?)?NO?]2?, with a central cobalt(III) ion and specific ligands, is 2. This charge determination is crucial for understanding the electronic structure and behavior of the complex ion, as well as its interactions with other species in various chemical environments.

For a deeper dive into the intricacies of coordination chemistry and the determination of charges on complex ions, further studies and references in inorganic chemistry textbooks and research papers are recommended.