Question

The correct structures $\mathrm{trans}-\left[{\mathrm{NiBr}}_2{\left({\mathrm{PPh}}_3\right)}_2\right]$ and $\mathrm{meridional}-\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_3{\left({\mathrm{NO}}_2\right)}_3\right]$ respectively are:

• A.

  

• B.

  

• C.

  

• D.

  

Answer 1

The correct option is B

The correct option is (B):

Explanation for the correct answer:

Trans and Meridional isomers:

1. Trans are basically the isomers in which the two similar atoms, same groups of many atoms or the same functional groups present there in the double bonded compound must be there on the opposite side to each other in the molecular structure.
2. So the angle between those atoms or group of atoms can be equal to $180°$and there can be less repulsion too.
3. Meridional isomers is basically a type of isomer which is actually a combination of both trans as well as cis isomer as when the three ligands around the metal are in same plane then it is said to be meridional isomer.
4. Trans isomer:
5. Meridional isomer:
6. Hence, in option (B), as ${\mathrm{PPh}}_3\mathrm{and}\mathrm{Br}$ are on opposite sides and 3 ligands each of ${\mathrm{NO}}_2\mathrm{and}{\mathrm{NH}}_3$ are also adjacent (cis) and opposite (trans) to their similar ones individually.

Explanation for the incorrect answers:

Option (A):

1. In the compound one, the similar groups are present on the opposite sides at the angle of $180°$ to each other and hence this isomer would be trans-isomer.
2. In compound second, only the two ligands are just identical to each other forming the facial isomer.
3. Hence, option (A) is incorrect.

Option (C):

1. As the two same groups in the first compound are present on the same side forming the cis isomer so it is not appropriate for the solution.
2. Here in the second compound, there is the combination of both trans and cis isomer as the three ligands around the metal are in the same plane and hence, this isomer would be the meridional isomer.
3. Hence, option (C) is incorrect.

Option (D):

1. As the two same groups in the first compound are present on the same side forming the cis isomer so it is not appropriate for the solution.
2. In compound second, only the two ligands are just identical to each other forming the facial isomer.
3. Hence, option (D) is incorrect.

Therefore, the correct answer is option (B):