Question

Write IUPAC names of the following coordination entities:
(a) \( [Fe(en)_2Cl_2]^+ \) 
(b) \( [Co(NH_3)_4(H_2O)Br]SO_4 \)
(c) \( [Ni(CN)_4]^{2-} \) 

Hint:

When naming coordination complexes, remember to follow these key steps:
Name the ligands first, in alphabetical order. Use prefixes like "di-", "tri-" to indicate the number of identical ligands.
The metal follows the ligands, with its oxidation state in parentheses in Roman numerals.
For anionic complexes, the metal name ends in "-ate" (e.g., nickel becomes "nickelate").
For neutral ligands, use their common names (e.g., ammonia for NH\(_3\), water for H\(_2\)O).

Answer 1

To solve the problem, we need to write the IUPAC names of the given coordination entities: (a) \( [Fe(en)_2Cl_2]^+ \), (b) \( [Co(NH_3)_4(H_2O)Br]SO_4 \), and (c) \( [Ni(CN)_4]^{2-} \).

1. Name \( [Fe(en)_2Cl_2]^+ \):
- Central metal: Fe, oxidation state: +3 (since 2 Cl⁻ give -2, total charge +1, so Fe is +3).
- Ligands: en (ethylenediamine, neutral) × 2, Cl⁻ × 2.
- Name ligands alphabetically: ‘en’ (di- for 2) as ethylenediamine, Cl as chloro.
- Complex is cationic, so metal name is iron(III).
IUPAC name: \( \text{Dichloridobis(ethylenediamine)iron(III)} \).

2. Name \( [Co(NH_3)_4(H_2O)Br]SO_4 \):
- Central metal: Co, oxidation state: +3 (Br⁻ gives -1, \( SO_4^{2-} \) gives -2, total charge 0, so Co is +3).
- Ligands in complex: \( NH_3 \) (neutral) × 4, \( H_2O \) (neutral) × 1, Br⁻ × 1.
- Name ligands alphabetically: ammine (\( NH_3 \), tetra- for 4), aqua (\( H_2O \)), bromido (Br⁻).
- Complex is cationic, counter ion is sulfate, metal name is cobalt(III).
IUPAC name: \( \text{Tetraammineaquabromidocobalt(III) sulfate} \).

3. Name \( [Ni(CN)_4]^{2-} \):
- Central metal: Ni, oxidation state: +2 (4 CN⁻ give -4, total charge -2, so Ni is +2).
- Ligands: CN⁻ × 4, named as cyano (but in IUPAC, ‘cyano’ is used, tetra- for 4).
- Complex is anionic, so metal name is nickelate(II).
IUPAC name: \( \text{Tetracyanonickelate(II)} \).

Final Answer:
(a) \( \text{Dichloridobis(ethylenediamine)iron(III)} \), (b) \( \text{Tetraammineaquabromidocobalt(III) sulfate} \), (c) \( \text{Tetracyanonickelate(II)} \).