Question

The name of the compound \[\left[ {{\text{Co}}{{\left( {{\text{N}}{{\text{H}}_{\text{3}}}} \right)}_{\text{5}}}{\text{N}}{{\text{O}}_{\text{2}}}} \right]{\text{C}}{{\text{l}}_{\text{2}}}\] will be?
A. Pentaaaminenitrocobalt(II) chloride
B. Pentaaaminenitrchlorideocobaltate(III)
C. Pentaaaminenitrocobalt(III) chloride
D. Pentanitrosoamminechlorocobaltate (III)

Answer 1

Hint: The name of coordination compounds is written by using the IUPAC rules of the naming of coordination compounds. Write the name of all ligands in alphabetical order then write the name of the metal with the charge of the metal.

Complete step by step answer:
Rules of writing the IUPAC name of the given compound:
Write the name of the cation part then the name of the anion part.
Write the name of the ligand in alphabetical order.
For neutral ligands, the name of the compound is used as such but for water use ‘aqua’ for ammonia use ‘ammine’.
For anionic ligands replace the,
Ide with o, Ate with ato, Ite with ito.
Use Greek prefix to denote the number of the ligand. If the name of the ligand has a Greek prefix then use bis for two, tris for three.
Write the name of the metal.
For the cationic complex, write the metal name as such.
For anionic complexes, use the suffix ‘ate’.
Write the name of \[\left[ {{\text{Co}}{{\left( {{\text{N}}{{\text{H}}_{\text{3}}}} \right)}_{\text{5}}}{\text{N}}{{\text{O}}_{\text{2}}}} \right]{\text{C}}{{\text{l}}_{\text{2}}}\] as follows:
In the above compound, five ammine, one nitro and counter ion chloro ligands are present.
Determine the charge of the metal as follows:
Suppose the charge of the metal is x. The charge of the ammine ligand is zero and the charge of nitro and the chloro ligands is - 1.
x + 5(0) + 1(-1) + 2(-1) = 0
x = + 3
So, the charge on the metal is + 3.
So, the name of the compound is, Pentaamminenitrocobalt(III) chloride.

Therefore, option (C) Pentaamminenitrocobalt(III) chloride, is correct.

Note: The molecules that bounds with the central atom are known as ligands. The chlorine is an atom whereas the chloro represents that chlorine is working as a ligand. The counter ion only balances the charge of the complex so, its number is not shown in the name of the complex.