Which of the following ligands are capable of forming chelate rings?

(I) ${\mathrm{NH}}_2– {\mathrm{CH}}_2– {\mathrm{CH}}_2– {\mathrm{NH}}_2$     (II) ${\mathrm{CH}}_3– {\mathrm{CH}}_2– {\mathrm{CH}}_2– {\mathrm{NH}}_2$

(III)${\mathrm{NH}}_2 – {\mathrm{CH}}_2– {\mathrm{CH}}_2– \mathrm{NH} – {\mathrm{CH}}_2– {\mathrm{COO}}^{-}$  (IV) ${\mathrm{NH}}_2– {\mathrm{CH}}_2– {\mathrm{CH}}_2–\stackrel{\oplus }{{\mathrm{NH}}_3}$

 In chelation, ring formation occurs because two atoms from the same ligand coordinate with the metal atom. This cannot happen if the ligand is mono dentate.

${\mathrm{CH}}_3 – {\mathrm{CH}}_2 – {\mathrm{CH}}_2 – {\mathrm{NH}}_2$ $\Rightarrow$Mono dentats ligand

${\mathrm{NH}}_2– {\mathrm{CH}}_2– {\mathrm{CH}}_2–\stackrel{\oplus }{{\mathrm{NH}}_3}$   $\Rightarrow$Mono dentats ligand