Question

Consider the following reaction and the statement
${\left[ {Co{{\left( {N{H_3}} \right)}_4}B{r_2}} \right]^ + } + B{r^ - } \to \left[ {Co{{\left( {N{H_3}} \right)}_3}B{r_3}} \right] + N{H_3}$
A)two isomers are produced if the reactant complex ion is a cis- isomer.
B) two isomers are produced if the reactant complex is a trans- isomer.
C) only one isomer is produced if the reactant complex ion is a trans-isomer.
D) only one isomer is produced if the reactant complex ion is a cis-isomer.
The correct statements are:
a) C and D
b) B and D
c) A and B
d) A and C

Answer 1

Geometrical isomerism is shown by the complexes which show the coordination number as four and six.
When the same ligand occupy the adjacent position in the polyhedral , then it is known as cis isomer .
Whereas when the same ligand occupies a different position in the polyhedral then it is known as trans isomer.

Complete step-by-step answer:
Geometrical isomerism is shown by the complexes which show the coordination number as four and six. It basically arises because of the difference in the geometrical arrangement of the ligands around the central metal ion.
Now ,we will discuss the two types of ligands which are as follows:
When the same ligand occupy the adjacent position in the polyhedral , then it is known as cis isomer .
Whereas when the same ligand occupies a different position in the polyhedral then it is known as trans isomer.
When there is one square planar complex of the type (MABXL) shows three isomers which are two of cis and one of trans.then it is seen in octahedral complexes with type $M{X_2}{L_4}$ THEN it shows cis and trans structures. Further when three same ligands are occupying position around the meridian of the octahedral then it is known as meridional isomer.
Talking about the reaction :
${\left[ {Co{{\left( {N{H_3}} \right)}_4}B{r_2}} \right]^ + } + B{r^ - } \to \left[ {Co{{\left( {N{H_3}} \right)}_3}B{r_3}} \right] + N{H_3}$
When we consider this reaction then we find out the two statements correct which are the first and the third statement. These statements states that which are as follows:
A)two isomers are produced if the reactant complex ion is a cis- isomer.
And the third statement states that
C) only one isomer is produced if the reactant complex ion is a trans-isomer.

Hence, option d) is correct which says that statement A and C are correct.

Note: We should keep this in mind that the tetrahedral complexes do not show geometrical isomerism because the position of the unidentate ligand attached to the central metal atom are same with respect to each other.