Question

When a co-ordination compound $Cr{Cl}_3\cdot 6H_{2}O$ is mixed with $AgN{O}_3$, $2$ moles of $AgCl$ are precipitated per mole of the compound. Write
(i) Structural formula of the complex.
(ii) IUPAC name of the complex.

Answer 1

There are three compounds with the formula

$CrC{l}_3.6H_{2}O$. One is violet, one is grey-green, and the third is deep

green.

The violet isomer produces 3 moles of silver chloride upon reaction with silver nitrate and does not lose water in a desiccator.

$\left[Cr\right(H_{2}O{)}_6]C{l}_3$ (violet)

The grey-green isomer gives 2 moles of silver chloride upon reaction with silver nitrate and loses one mole of water when stored in a desiccator.

$\left[Cr\right(H_{2}O{)}_{5}Cl]C{l}_2.H_{2}O$ (grey-green)

The deep green isomer gives 1 mole of silver chloride upon reaction with silver nitrate and loses two moles of water when stored in a desiccator.

$\left[Cr\right(H_{2}O{)}_{4}C{l}_2]Cl.2H_{2}O$ (deep green)

(i)The given compound has a structural formula $\left[Cr\right(H_{2}O{)}_{5}Cl]C{l}_2.H_{2}O$

(ii) The IUPAC name of the complex is $Pentaaquachlorochromium\left(III\right)dichloridemonohydrate$