Question

Select the correct statement :

• A. Chelation effect is maximum for five and six membered rings
• B. Greater the charge on the central metal cation, greater the value of $\Delta$ (CFSE)
• C. In complex ion $[Co{F}_6{]}^{3-},F^{-}$ is a weak field ligand, so that ${\Delta }_{oct}<P$ (Pairing energy) and it is low spin complex.
• D. $\left[CoC{l}_2\right(N{H}_3{)}_2\left(en\right){]}^{\oplus }$ complex ion will have four different isomers.

Answer 1

Answer: (A), (B), (D)

The correct options are
A Chelation effect is maximum for five and six membered rings
B Greater the charge on the central metal cation, greater the value of $\Delta$ (CFSE)
D $\left[CoC{l}_2\right(N{H}_3{)}_2\left(en\right){]}^{\oplus }$ complex ion will have four different isomers.

(A) Chelation effect is maximum for five and six remember rings as there is no strain in five and six remember rings.
Thus option A is correct.

(B) Greater the charge on the central metal cation, greater the value of (CFSE). This is because greater will be the attraction between metal and ligands. This will result in greater interaction.
Thus option B is correct.

(C) In the complex cation, $[Co{F}_6{]}^{3-},F^{-}$ is a weak field ligand. Hence, ${\Delta }_{oct}<P$. Hence, pairing will not occur. The complex will be a high spin complex.
Thus option C is incorrect.

(D) The complex $\left[CoC{l}_2\right(N{H}_3{)}_2\left(en\right){]}^{\oplus }$ has four geometrical isomers, one cis and three trans. The cis form is optically active and exists as d and $l$ isomers. The trans isomer is optically inactive. Thus total four stereoisomers are present.
Thus option D is correct.