Question

The ionisation isomer of $\left[Cr\right(H_{2}O{)}_{4}Cl\left(N{O}_2\right)]Cl$ is:

• A. $\left[Cr\right(H_{2}O{)}_4\left(O_{2}N\right)]C{l}_2$
• B. $\left[Cr\right(H_{2}O{)}_{4}C{l}_2\left]\right(N{O}_2)$
• C. $\left[Cr\right(H_{2}O{)}_{4}Cl\left(ONO\right)]Cl$
• D. $\left[Cr\right(H_{2}O{)}_{4}C{l}_2\left(N{O}_2\right)]H_{2}O$

Answer 1

Answer: (B)

$\left[Cr\right(H_{2}O{)}_{4}C{l}_2\left]\right(N{O}_2)$

Ionisation isomers are complexes that produces different ions in solution, i.e., they have ions interchanged inside and outside the coordination sphere.
$\left[Cr\right(H_{2}O{)}_{4}Cl\left(N{O}_2\right)]Cl$ and $\left[Cr\right(H_{2}O{)}_{4}C{l}_2]N{O}_2$ have different ions inside and outside the coordination sphere and hence are ionisation isomers.