Question

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

• A. $M(AA')_2$
• B. $M(AA)_3$
• C. MABCD
• D. $MA_3X_3$

Answer 1

Answer: (D)

$MA_3X_3$

Answer 2

The compounds of the formula $\left[ MA _{3} B _{3}\right]$ 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.