JEE Main · 2023 · 11 Apr 2023 · Shift 1 · Coordination Compounds

Meridional (mer) and facial (fac) isomers exist for octahedral complexes of the type $[{\mathrm{MA}}_3{\mathrm{B}}_3]$. In the mer isomer, three identical ligands occupy meridional positions (forming a plane through the metal), while in the fac isomer, they occupy one triangular face. $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_3{\left({\mathrm{NO}}_2\right)}_3\right]$ is an $[{\mathrm{MA}}_3{\mathrm{B}}_3]$ type complex and can exist as both fac and mer isomers.