What is the name of the complex [Ni(H2O)4(NH2CH2CH2NH2)]SO4.5H2O as per IUPAC rules?
Answer & explanation
Correct answer: option 2
The correct answer is option 2. Tetraaquaethylenediamine nickel (II) sulphate-5-water.
Let us break down the naming of the complex \([Ni(H_2O)_4(NH_2CH_2CH_2NH_2)]SO_4 \cdot 5H_2O\) step by step according to IUPAC rules.
The complex consists of:
Metal ion: Nickel (Ni) in the +2 oxidation state (\(Ni^{2+}\)).
Ligands:
\(H_2O\) (water): Aqua ligand.
\(NH_2CH_2CH_2NH_2\) (ethylenediamine): Ethylenediamine ligand.
Counter Ion: \(SO_4\) (sulfate).
Hydrate: \(5H_2O\) (five water molecules as part of the crystal lattice).
Steps to Name the Complex:
1. Determine Coordination Number: Nickel is coordinated to \(4\) water molecules (\(H_2O\)) and \(1\) ethylenediamine molecule (\(NH_2CH_2CH_2NH_2\)), making a total coordination number of \(5\).
2. Name the Ligands:
Water (\(H_2O\)) is named as "aqua".
Ethylenediamine (\(NH_2CH_2CH_2NH_2\)) is named as "ethylenediamine".
3. Order Ligands Alphabetically: Ligands are named in alphabetical order regardless of their charge.
4. Construct the Name:
Begin with the number of each type of ligand. Follow with the name of each ligand, specifying its coordination number. Include the metal ion's oxidation state and the name of the counter ion.
Let us validate the correct naming based on the options provided:
Option 1: Aquaethylenediamine nickel (II) sulphate-1-water - Incorrect because it does not correctly describe the number of water molecules in the hydrate.
Option 2: Tetraaquaethylenediamine nickel (II) sulphate-5-water - Incorrect because it does not correctly describe the coordination number of the ethylenediamine ligand.
Option 3: Tetraaqua bis (ethylenediamine) nickel (II) sulphate-5-water - Correct naming because it accurately describes:
"Tetraaqua" indicates \(4\) water molecules.
"Bis(ethylenediamine)" indicates \(1\) ethylenediamine molecule.
"Nickel (II)" specifies the oxidation state of nickel.
"Sulphate-5-water" indicates \(1\) sulphate molecule and \(5\) water molecules.
Based on the correct application of IUPAC naming rules and the analysis of options, the correct name for the complex \([Ni(H_2O)_4(NH_2CH_2CH_2NH_2)]SO_4 \cdot 5H_2O\) is: \(\text{Tetraaqua bis (ethylenediamine) nickel (II) sulphate-5-water} \).
This name accurately reflects the composition and structure of the complex as specified.