Write the preparation of interhalogen compounds and state their uses. Discuss the properties of interhalogen compounds.

(N/A) Preparation: The interhalogen compounds can be prepared by the direct combination or by the action of a halogen on lower interhalogen compounds.
$Cl_{2} + F_{2} \xrightarrow{437 \ K} 2 ClF$; $I_{2} + 3 Cl_{2} \rightarrow 2 ICl_{3}$
$Cl_{2} + 3 F_{2} \xrightarrow{573 \ K} 2 ClF_{3}$; $Br_{2} + 3 F_{2} \rightarrow 2 BrF_{3}$
$I_{2} + Cl_{2} \rightarrow 2 ICl$; $Br_{2} + 5 F_{2} \rightarrow 2 BrF_{5}$
Uses of interhalogen compounds: These compounds can be used as non-aqueous solvents.
They are very useful fluorinating agents.
$ClF_{3}$ and $BrF_{3}$ are used for the production of $UF_{6}$ in the enrichment of $U-235$.
$U_{(s)} + 3 ClF_{3(l)} \rightarrow UF_{6(g)} + 3 ClF_{(g)}$
$(i)$ Physical properties: These are all covalent molecules and are diamagnetic in nature.
They are volatile solids or liquids at $298 \ K$ except $ClF$ which is a gas.
Their physical properties are intermediate between those of constituent halogens except that their melting point and boiling point are slightly higher than expected.
Some Properties of Interhalogen Compounds

Type and Formula	Physical state,colour,and Structure
$XX^{\prime}$: $ClF, BrF, IF^{a}, BrCl^{b}, ICl, IBr$	colourless gas,pale brown gas,detected spectroscopically,gas,ruby red solid ($\alpha$-form),brown red solid ($\beta$-form),black solid; Structure: Linear
$XX^{\prime}_{3}$: $ClF_{3}, BrF_{3}, IF_{3}, ICl_{3}^{c}$	colourless gas,yellow green liquid,yellow powder,orange solid; Structure: Bent $T$-shaped
$XX^{\prime}_{5}$: $IF_{5}, BrF_{5}, ClF_{5}$	colourless gas but solid below $77 \ K$,colourless liquid,colourless liquid; Structure: Square Pyramidal
$XX^{\prime}_{7}$: $IF_{7}$	colourless gas; Structure: Pentagonal Bipyramidal

$a$ Very unstable; $b$ The pure solid is known at room temperature; $c$ Dimerises as $Cl$-bridged dimer $(I_{2}Cl_{6})$.
The molecular structures of interhalogen compounds can be explained by $VSEPR$ theory.
$(ii)$ Chemical properties: Interhalogen compounds are more reactive than halogens (except fluorine) because of weak $X-X^{\prime}$ bonds as compared to halogen-halogen bonds.
Interhalogens undergo hydrolysis giving a halide ion derived from the smaller halogen and a hypohalite (when $XX^{\prime}$),halite (when $XX^{\prime}_{3}$),halate (when $XX^{\prime}_{5}$) and perhalate (when $XX^{\prime}_{7}$) anion derived from the larger halogen.
$XX^{\prime} + H_{2}O \rightarrow HX^{\prime} + HOX$
$XX^{\prime}_{3} + 2 H_{2}O \rightarrow 3 HX^{\prime} + HOXO$
$XX^{\prime}_{5} + 3 H_{2}O \rightarrow 5 HX^{\prime} + HOXO_{2}$
$XX^{\prime}_{7} + 4 H_{2}O \rightarrow 7 HX^{\prime} + H_{5}IO_{6}$ (ortho periodic acid)