Question

Fac-mer isomerism is associated with which one of the following complexes? (M=central metal)

• A. $\left[\right.\text{M}\left(\text{A} \text{A}\right)_{2}\left]\right.$
• B. $\left[\right.\text{}\text{M}\text{A}_{3}\text{B}_{3}\left]\right.$
• C. $\left[\right.\text{M}\left(\text{A} \text{A}\right)_{3}\left]\right.$
• D. $\left[\right.\text{M}\text{A}\text{B}\text{C}\text{D}\left]\right.$

Answer 1

Answer: (B)

Fac-mer isomerism is associated with $\left[\right.\text{}\text{}\text{M}\text{A}_{3}\text{B}_{3}\left]\right.$ type complexes. 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.
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