Question

The IUPAC name of the complex \[[Pt{(N{H_3})_2}Cl(N{H_2}C{H_3})]Cl\]is:
A. Diammine Dichloride(methanamine) platinum (II) chloride
B. Bisammine (methanamine) chlorido platinum (II) chloride
C. Diammine Dichloride (aminomethane) platinum (II) chloride
D. Diammine (methanamine) chlorido platinum (II) chloride

Answer 1

Hint: Name the ligands first in alphabetical order without spaces. The metal is named next. If the metal has a positive oxidation number, its name is written normally. If its oxidation number is negative, the name of the metal will have the suffix -ate. The oxidation number of the metal is written in Roman numerals inside parentheses following the name of the metal.

Complete Step by Step Solution:
In naming a coordination compound, the ligands' names are written first, in alphabetical order, without any spaces.
Neutral ligands are named as such. Anionic ligands that end in “-ide” are replaced in the end by “-o”. Anions ending in “-ate” are replaced by “-ato” and those ending in “-ite” are replaced by “-ito”.
The number of ligands is indicated by using prefixes such as “bi-“, “tri-“, “tetra-“ etc.
In the coordination sphere of \[[Pt{(N{H_3})_2}Cl(N{H_2}C{H_3})]Cl\], we have the following:

Ligands	Ligand type	IUPAC name
Two \[N{H_3}\](amine) ligands	Neutral	Diammine
One \[Cl\](chloride) ligand	Anionic	Chlorido
One \[N{H_2}C{H_3}\](methanamine) ligand	Neutral	Methanamine

The IUPAC names of the ligands are written in alphabetical order. Thus, so far, the name of the complex is Diamminechlorido(methanamine)_______

The metal must be named next. For this, we must calculate the oxidation number of the metal first. In this complex, let’s assume the oxidation number of platinum to be x. Since the coordination sphere is attached to a chloride ion (which has an oxidation number of -1), it must have an oxidation number of +1. The oxidation number of platinum can be calculated as follows:
\[\begin{array}{l}{[Pt{(N{H_3})_2}Cl(N{H_2}C{H_3})]^ + }\\{\rm{ }}x{\rm{ 0 - 1 0}}\end{array}\]
\[\therefore {\rm{ x + 0 - 1 + 0 = + 1}}\]
\[ \Rightarrow x = 1 + 1\]
\[ \Rightarrow x = + 2\]
Since platinum is in a +2 oxidation state, it will be named platinum(II). The IUPAC name of the complex, at this point, is Diamminechlorido(methanamine) platinum(II)______

Since the coordination sphere is attached to a chloride ion, its name comes at the end to complete the IUPAC name of the complex.
Therefore, the complete IUPAC name of the complex is Diamminechlorido(methanamine) platinum(II) chloride.
Thus, option A is correct.

Note: The numeric prefixes for polydentate ligands such as ethylenediamine, oxalate etc. are “bis- “, “tris- “, “tetrakis- “etc. and not the usual “bi-“, “tri-“ etc. Care must be taken to identify polydentate ligands and use appropriate numeric prefixes. Any confusion here will make the entire name wrong.