Question

Fac, mer isomerism is associated with which of the following general formula ?

• A. $M(A{A}^{\prime }{)}_2$
• B. $M(AA{)}_3$
• C. MABCD
• D. $M{A}_3{X}_3$

Answer 1

Answer: (D)

The compounds of the formula $\left[M{A}_3{B}_3\right]$ exhibit fac and mer isomerism.
The fac isomer is also known as facial isomer or cis isomer.
Three $A$ ligands are present on one triangular face and three $B$ ligands are present on opposite triangular face.
The mer isomer is also known as meridional isomer or trans isomer.