Question

The anion of acetylacetone (acac) Forms $\mathrm{Co}{\left(\mathrm{acac}\right)}_3$Chelates With ${\mathrm{Co}}^{+3}$. The rings of the chelates are _________.

• A. Six Membered
• B. Five Membered
• C. Four Membered
• D. Three Membered

Answer 1

The correct option is A

Six Membered

The explanation for the correct options:

The Ligand acetylacetone(acac) forms 6 member chelate ring in the complex $\mathrm{Co}{\left(\mathrm{acac}\right)}_3$

Chelates: An organic compound formed when a polydentate ligand bonds to a central metal atom is known as chelates.

The explanation for the incorrect option:

Option B:

Five-Membered: These ligands are able to adapt themselves to the requirement of the different metals by changing the MN distance and NMN angles

Option C:
Four-member rings can be formed with simple oxy anion ligands such as nitrate.

For example,[${\left[\mathrm{Co}{\left(\mathrm{dien}\right)}_2\right]}^{3+}$, contains diethylenetriamine as ligand, with denticity of 2, and this binds with the central atom as,

Option D:
Three membered rings are the ${\left[\mathrm{Cu}\right(\mathrm{trien}\left)\right]}^{2+}$ ligand that has denticity of $3$.

As the ligand when attached to the central atom forms 3 rings, chelate rings are 3

So the structure is,

​Hence, Option (A) is correct.