What is the IUPAC name of [Co((NH3)2sar]Cl5?
The correct answer and explanation is:
The IUPAC name of the compound [Co((NH3)2sar)]Cl5 is diamminesarconate(III) chloride pentachloride.
Explanation:
- Complex Identification:
- The central metal ion is cobalt (Co), which has an oxidation state of +3 as indicated by the complex’s charge balance. In this complex, cobalt is coordinated to two ammonia (NH3) ligands and one sar (sarconate) ligand.
- The ammonia (NH3) ligands are neutral molecules and are called ammine in the IUPAC nomenclature.
- The sarconate ligand (usually abbreviated as sar) is a bidentate ligand. It forms two bonds with the central metal ion.
- The remaining part of the complex includes chloride ions, which are present as counterions outside the coordination sphere of the cobalt.
- Ligand Naming:
- Ammine is used to describe ammonia ligands.
- The sar ligand is named sarconate, representing a bidentate ligand that attaches to the metal via two donor atoms.
- Coordination Number:
- The cobalt ion is surrounded by five ligands (two ammine ligands and one sarconate ligand, along with five chloride ions).
- The chloride ions are considered counterions and do not participate in the coordination with the central metal.
- Oxidation State of Metal:
- The cobalt ion has an oxidation state of +3, which is indicated by the “(III)” suffix.
- Complex Charge:
- The complex has a positive charge of +1 because the total charge from the ligands is neutral, and the chloride counterions balance this by being negatively charged.
Thus, the full IUPAC name reflects both the identity of the ligands and the overall charge and structure of the complex, leading to the name diammine sarconate(III) chloride pentachloride.