Structure of ${\mathrm{ICl}}_2^{-}$ is

${\mathrm{ICl}}_2^{-}$

No. of hybrid orbitals=$\frac{1}{2}\left(\mathrm{V}+\mathrm{M}- \mathrm{charge}\right)=\frac{1}{2}(7+2+1)=5\to {\mathrm{sp}}^3\mathrm{d} \mathrm{hybridization}$

The central atom 'I' has 3 lone pairs and 2 bond pairs, So the shape is distorted trigonal bipyramidal, i.e. linear.