(i) Write down the IUPAC name of the following complex:

(en)]Cl

(ii) Write the formula for following complex:

Pentaamminenitrito-O-Cobalt(III)

(i)

Diamminedichloro (ethane-1,2-diammine) chromium (III)chloride

*First we have to name the species (ligands and metal) within square brackets.

*The ligands are named in alphabetical order irrespective of their number present. Since ‘(en)’ is a bidentate ligand with substituents its name is written in brackets. *Once all the ligands are named then the central metal ion with oxidation state has to be named. Here the central metal is Chromium bonded to 2 ammonia (neutral), 3 chloride(negatively charged) and one ethane-1,2-diammine(neutral). Since the complex is having 3 negatively charged ions the positive charge on chromium should also be 3.

*One chloride is outside the square brackets hence named after the central metal ion.

(ii) Co(NH₃)₅ (ONO)]²⁺

When writing the formula of a complex first central metal ion is written in the square brackets. Next the ligands follow.

Here we have 2 ligands. Pentaamine implies 5 molecules of ammonia, and one nitrito implies nitro group. Nitro can be linked through nitrogen or oxygen as both have lone pairs to donate. It is mentioned in the name as Nitrito-O- implies the linkage is through Oxygen hence written as -ONO-.