Question

Which one of the following is an incorrect statement pertaining to the properties of Coordination compounds?

• A. A square planar complex of the type Mabcd, where a, b, c, and d are unidentate ligands, exhibits geometrical isomerism and exists in one cis-form and two trans-forms.
• B. [Co(NH_3)_5NO_2]Cl_2 exists in 2 forms, the red form and the yellow form which are linkage isomers.
• C. [Fe(CN)_6]^{3-} is called a Low spin complex.
• D. Out of cis-[CrCl_2(ox)_2]^{3-} and trans-[CrCl_2(ox)_2]^{3-}, the trans isomer is optically inactive.

Hint:

In coordination compounds, linkage isomerism occurs when a ligand can coordinate to the metal center in two different ways, as seen in the case of [Co(NH_3)_5NO_2]Cl_2. Always check for the geometry and symmetry to determine isomerism.

Answer 1

The Correct Option is A

The incorrect statement is Option (A) Here's why: - Option A: A square planar complex of the type Mabcd, where a, b, c, and d are unidentate ligands, exhibits geometrical isomerism and exists in one cis-form and two trans-forms. - This is incorrect because a square planar complex with four different unidentate ligands (Mabcd) will not exhibit geometrical isomerism with one cis-form and two trans-forms. A square planar complex can only exhibit two forms (cis and trans) when it has two similar ligands, not four different ones. - Option B: [Co(NH_3)_5NO_2]Cl_2 exists in two forms, the red form and the yellow form, which are linkage isomers. - This statement is true because linkage isomerism arises when a ligand can coordinate to the metal center through different atoms. In this case, the nitrite (NO_2) can bind either through the nitrogen or the oxygen atom, resulting in different linkage isomers. - Option C: [Fe(CN)_6]^{3-} is called a Low spin complex. - This statement is true because [Fe(CN)_6]^{3-} is an octahedral complex with a low-spin configuration due to the strong field ligand CN^-. - Option D: Out of cis-[CrCl_2(ox)_2]^{3-} and trans-[CrCl_2(ox)_2]^{3-}, the trans isomer is optically inactive. - This statement is true because the trans isomer has a plane of symmetry and is therefore optically inactive, while the cis isomer lacks a plane of symmetry and can be optically active.