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

The task is to determine the IUPAC nomenclature for the provided coordination entities: (a) \( [Fe(en)_2Cl_2]^+ \), (b) \( [Co(NH_3)_4(H_2O)Br]SO_4 \), and (c) \( [Ni(CN)_4]^{2-} \).

1. IUPAC Name for \( [Fe(en)_2Cl_2]^+ \):
The central metal is Fe. Its oxidation state is +3, calculated as follows: 2 Cl⁻ contribute -2 to the charge, and the overall complex charge is +1, thus Fe must be +3. The ligands are two ethylenediamine (en, neutral) and two chloride ions (Cl⁻). Ligands are named alphabetically: ethylenediamine (bis- for 2) and chloro. Since the complex is cationic, the metal is named iron(III).
The IUPAC name is \( \text{Dichloridobis(ethylenediamine)iron(III)} \).

2. IUPAC Name for \( [Co(NH_3)_4(H_2O)Br]SO_4 \):
The central metal is Co. Its oxidation state is +3, calculated as follows: Br⁻ contributes -1, \( SO_4^{2-} \) contributes -2, and the overall charge is 0, therefore Co must be +3. The ligands within the complex are four ammonia molecules (\( NH_3 \), neutral), one water molecule (\( H_2O \), neutral), and one bromide ion (Br⁻). Ligands are named alphabetically: ammine (\( NH_3 \), tetra- for 4), aqua (\( H_2O \)), and bromido (Br⁻). The complex is cationic, with sulfate (\( SO_4^{2-} \)) as the counter ion. The metal is named cobalt(III).
The IUPAC name is \( \text{Tetraammineaquabromidocobalt(III) sulfate} \).

3. IUPAC Name for \( [Ni(CN)_4]^{2-} \):
The central metal is Ni. Its oxidation state is +2, calculated as follows: 4 CN⁻ ions contribute -4 to the charge, and the overall complex charge is -2, thus Ni must be +2. The ligand is four cyanide ions (CN⁻), named as cyano (tetra- for 4). Since the complex is anionic, the metal is named nickelate(II).
The IUPAC name is \( \text{Tetracyanonickelate(II)} \).

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