Nomenclature Of Coordination Compounds

To determine the IUPAC name of the compound, we need to follow the naming rules for coordination compounds. In this compound, we have: - Cr as the central metal ion, with an oxidation state of +3, indicated by the ligands and the charge balance. - The ligands are: - H O (water), which is called "aqua", - NH (ammonia), which is called "ammine". - The complex is chloride-terminated, indicated by the Cl outside the coordination sphere. The IUPAC name is Chromium(III) ammine aqua chloride, reflecting the coordination of ammine and aqua ligands to chromium, with the chloride as a counter ion.

Concept: Rules for naming coordination compounds:
• Ligands named alphabetically
• Neutral ligands: ammine ( ), aqua ( )
• Oxidation state written in Roman numerals

Step 1: Identify ligands.


Step 2: Arrange alphabetically.
ammine comes before aqua:

Step 3: Find oxidation state of Co.


Step 4: Write final name.

Step 1: Understanding the Concept:
Naming coordination compounds: Ligands in alphabetical order, metal name, oxidation state in Roman numerals, then counter ion.

Step 2: Detailed Explanation:
Complex ion: .
- Ligand: en = ethane-1,2-diamine (neutral, bidentate).
- Three ligands → tris(ethane-1,2-diamine).
- Metal: cobalt. Oxidation state: en is neutral, SO charge = -3 overall. Let Co = x, then 2x + 3(-2) = 0 ⇒ 2x = 6 ⇒ x = +3.
- Counter ion: sulphate.
Name: tris(ethane-1,2-diamine)cobalt(III) sulphate.

Step 3: Final Answer:
The correct IUPAC name is tris(ethane-1,2-diamine)cobalt(III) sulphate.

Step 1:


Step 2:


Step 3:


Step 4:


Step 5:
Final Answer:

Step 1: Understanding the Concept:
Naming coordination compounds follows strict IUPAC nomenclature rules. The cation is named before the anion. Within the complex ion, ligands are named in alphabetical order, followed by the central metal atom and its oxidation state in Roman numerals.
Step 2: Key Formula or Approach:
The approach involves identifying the ligands, determining their alphabetical order, calculating the oxidation state of the central metal, and identifying the linkage of ambidentate ligands. Let the oxidation state of the metal be and use the formula: .
Step 3: Detailed Explanation:
Let's break down the complex :
1. Identify the parts: The complex cation is and the counter anions are two (chloride).
2. Name the ligands:
- There are five ligands. is named "ammine". Since there are five, we use the prefix "penta", making it "pentaammine".
- There is one ligand. This is an ambidentate ligand derived from nitrite. Because it is written as ONO, it is coordinating through the oxygen atom. Therefore, it is named "nitrito-O".
3. Alphabetize ligands: "ammine" comes before "nitrito-O".
4. Calculate Oxidation State of Cobalt (Co):
Let be the oxidation state of Co.
Charge of
Charge of
Charge of the complex sphere must be to balance the two ions.



So, the oxidation state is (III).
5. Assemble the name:
Combine the ligand names, metal name, and oxidation state: pentaamminenitrito-O-cobalt(III).
Add the counter ion at the end: chloride.
Step 4: Final Answer:
The full IUPAC name is pentaamminenitrito-O-cobalt(III) chloride.

Step 1: Understanding the Concept:
Naming coordination compounds requires following IUPAC rules: name the cation first, then the anion. Inside the complex ion, list ligands alphabetically, followed by the metal and its oxidation state in Roman numerals.

Step 2: Key Formula or Approach:
1. Identify the complex ion and counter ion.
2. Identify and name the ligands, determining their alphabetical order.
3. Use appropriate prefixes for the number of ligands (di-, tri- or bis-, tris- for complex ligands).
4. Calculate the oxidation state of the central metal.

Step 3: Detailed Explanation:
Let's break down the formula :
- The cation is the complex ion .
- The anion is chloride ( ).
- Ligands:
- ' ' represents chloride. As a ligand, it is named 'chlorido'. There are two, so we use the prefix 'di-' dichlorido.
- ' ' represents ethylenediamine. Its systematic IUPAC name is 'ethane-1,2-diamine'. Since the ligand name contains a number/prefix, we use 'bis-' for two of them bis(ethane-1,2-diamine).
- Alphabetical order: 'chlorido' comes before 'ethane-1,2-diamine'.
- Central Metal: Cobalt (Co). Since the complex is a cation, the name remains 'cobalt'.
- Oxidation State:
Let the oxidation state of Co be .
Charge of chlorido ligand =
Charge of 'en' ligand = (neutral)
Overall charge of the complex cation (to balance the one anion outside).


The oxidation state is (III).
Assembling the name: dichloridobis(ethane-1,2-diamine)cobalt(III) chloride.

Step 4: Final Answer:
The IUPAC name is dichloridobis(ethane-1,2-diamine)cobalt(III) chloride.